Merge pull request #4174 from andrestc/hostkeycallback

ssh: Adds HostKeyCallback
2017-07-10 16:16:10 -07:00
parent ce676b940b b63e1e8b2c
commit fcfbd11c80
40 changed files with 5760 additions and 1134 deletions
@@ -547,15 +547,15 @@
 		},
 		{
 			"ImportPath": "golang.org/x/crypto/curve25519",
-			"Rev": "beef0f4390813b96e8e68fd78570396d0f4751fc"
+			"Rev": "51714a8c4ac1764f07ab4127d7f739351ced4759"
 		},
 		{
 			"ImportPath": "golang.org/x/crypto/ssh",
-			"Rev": "beef0f4390813b96e8e68fd78570396d0f4751fc"
+			"Rev": "51714a8c4ac1764f07ab4127d7f739351ced4759"
 		},
 		{
 			"ImportPath": "golang.org/x/crypto/ssh/terminal",
-			"Rev": "beef0f4390813b96e8e68fd78570396d0f4751fc"
+			"Rev": "51714a8c4ac1764f07ab4127d7f739351ced4759"
 		},
 		{
 			"ImportPath": "golang.org/x/net/context",
@@ -644,6 +644,14 @@
 		{
 			"ImportPath": "google.golang.org/cloud/internal",
 			"Rev": "975617b05ea8a58727e6c1a06b6161ff4185a9f2"
+		},
+		{
+			"ImportPath": "golang.org/x/crypto/ed25519",
+			"Rev": "51714a8c4ac1764f07ab4127d7f739351ced4759"
+		},
+		{
+			"ImportPath": "golang.org/x/crypto/ed25519/internal/edwards25519",
+			"Rev": "51714a8c4ac1764f07ab4127d7f739351ced4759"
 		}
 	]
 }
@@ -151,8 +151,9 @@ func NewNativeConfig(user string, auth *Auth) (ssh.ClientConfig, error) {
 	}

 	return ssh.ClientConfig{
-		User: user,
-		Auth: authMethods,
+		User:            user,
+		Auth:            authMethods,
+		HostKeyCallback: ssh.InsecureIgnoreHostKey(),
 	}, nil
 }

@@ -0,0 +1,3 @@
+# This source code refers to The Go Authors for copyright purposes.
+# The master list of authors is in the main Go distribution,
+# visible at https://tip.golang.org/AUTHORS.
@@ -0,0 +1,3 @@
+# This source code was written by the Go contributors.
+# The master list of contributors is in the main Go distribution,
+# visible at https://tip.golang.org/CONTRIBUTORS.
@@ -0,0 +1,8 @@
+// Copyright 2012 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// This code was translated into a form compatible with 6a from the public
+// domain sources in SUPERCOP: https://bench.cr.yp.to/supercop.html
+
+#define REDMASK51     0x0007FFFFFFFFFFFF
@@ -3,12 +3,12 @@
 // license that can be found in the LICENSE file.

 // This code was translated into a form compatible with 6a from the public
-// domain sources in SUPERCOP: http://bench.cr.yp.to/supercop.html
+// domain sources in SUPERCOP: https://bench.cr.yp.to/supercop.html

 // +build amd64,!gccgo,!appengine

-DATA ·REDMASK51(SB)/8, $0x0007FFFFFFFFFFFF
-GLOBL ·REDMASK51(SB), 8, $8
+// These constants cannot be encoded in non-MOVQ immediates.
+// We access them directly from memory instead.

 DATA ·_121666_213(SB)/8, $996687872
 GLOBL ·_121666_213(SB), 8, $8
@@ -2,87 +2,64 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.

-// This code was translated into a form compatible with 6a from the public
-// domain sources in SUPERCOP: http://bench.cr.yp.to/supercop.html
-
 // +build amd64,!gccgo,!appengine

-// func cswap(inout *[5]uint64, v uint64)
+// func cswap(inout *[4][5]uint64, v uint64)
 TEXT ·cswap(SB),7,$0
 	MOVQ inout+0(FP),DI
 	MOVQ v+8(FP),SI

-	CMPQ SI,$1
-	MOVQ 0(DI),SI
-	MOVQ 80(DI),DX
-	MOVQ 8(DI),CX
-	MOVQ 88(DI),R8
-	MOVQ SI,R9
-	CMOVQEQ DX,SI
-	CMOVQEQ R9,DX
-	MOVQ CX,R9
-	CMOVQEQ R8,CX
-	CMOVQEQ R9,R8
-	MOVQ SI,0(DI)
-	MOVQ DX,80(DI)
-	MOVQ CX,8(DI)
-	MOVQ R8,88(DI)
-	MOVQ 16(DI),SI
-	MOVQ 96(DI),DX
-	MOVQ 24(DI),CX
-	MOVQ 104(DI),R8
-	MOVQ SI,R9
-	CMOVQEQ DX,SI
-	CMOVQEQ R9,DX
-	MOVQ CX,R9
-	CMOVQEQ R8,CX
-	CMOVQEQ R9,R8
-	MOVQ SI,16(DI)
-	MOVQ DX,96(DI)
-	MOVQ CX,24(DI)
-	MOVQ R8,104(DI)
-	MOVQ 32(DI),SI
-	MOVQ 112(DI),DX
-	MOVQ 40(DI),CX
-	MOVQ 120(DI),R8
-	MOVQ SI,R9
-	CMOVQEQ DX,SI
-	CMOVQEQ R9,DX
-	MOVQ CX,R9
-	CMOVQEQ R8,CX
-	CMOVQEQ R9,R8
-	MOVQ SI,32(DI)
-	MOVQ DX,112(DI)
-	MOVQ CX,40(DI)
-	MOVQ R8,120(DI)
-	MOVQ 48(DI),SI
-	MOVQ 128(DI),DX
-	MOVQ 56(DI),CX
-	MOVQ 136(DI),R8
-	MOVQ SI,R9
-	CMOVQEQ DX,SI
-	CMOVQEQ R9,DX
-	MOVQ CX,R9
-	CMOVQEQ R8,CX
-	CMOVQEQ R9,R8
-	MOVQ SI,48(DI)
-	MOVQ DX,128(DI)
-	MOVQ CX,56(DI)
-	MOVQ R8,136(DI)
-	MOVQ 64(DI),SI
-	MOVQ 144(DI),DX
-	MOVQ 72(DI),CX
-	MOVQ 152(DI),R8
-	MOVQ SI,R9
-	CMOVQEQ DX,SI
-	CMOVQEQ R9,DX
-	MOVQ CX,R9
-	CMOVQEQ R8,CX
-	CMOVQEQ R9,R8
-	MOVQ SI,64(DI)
-	MOVQ DX,144(DI)
-	MOVQ CX,72(DI)
-	MOVQ R8,152(DI)
-	MOVQ DI,AX
-	MOVQ SI,DX
+	SUBQ $1, SI
+	NOTQ SI
+	MOVQ SI, X15
+	PSHUFD $0x44, X15, X15
+
+	MOVOU 0(DI), X0
+	MOVOU 16(DI), X2
+	MOVOU 32(DI), X4
+	MOVOU 48(DI), X6
+	MOVOU 64(DI), X8
+	MOVOU 80(DI), X1
+	MOVOU 96(DI), X3
+	MOVOU 112(DI), X5
+	MOVOU 128(DI), X7
+	MOVOU 144(DI), X9
+
+	MOVO X1, X10
+	MOVO X3, X11
+	MOVO X5, X12
+	MOVO X7, X13
+	MOVO X9, X14
+
+	PXOR X0, X10
+	PXOR X2, X11
+	PXOR X4, X12
+	PXOR X6, X13
+	PXOR X8, X14
+	PAND X15, X10
+	PAND X15, X11
+	PAND X15, X12
+	PAND X15, X13
+	PAND X15, X14
+	PXOR X10, X0
+	PXOR X10, X1
+	PXOR X11, X2
+	PXOR X11, X3
+	PXOR X12, X4
+	PXOR X12, X5
+	PXOR X13, X6
+	PXOR X13, X7
+	PXOR X14, X8
+	PXOR X14, X9
+
+	MOVOU X0, 0(DI)
+	MOVOU X2, 16(DI)
+	MOVOU X4, 32(DI)
+	MOVOU X6, 48(DI)
+	MOVOU X8, 64(DI)
+	MOVOU X1, 80(DI)
+	MOVOU X3, 96(DI)
+	MOVOU X5, 112(DI)
+	MOVOU X7, 128(DI)
+	MOVOU X9, 144(DI)
 	RET
@@ -8,6 +8,10 @@

 package curve25519

+import (
+	"encoding/binary"
+)
+
 // This code is a port of the public domain, "ref10" implementation of
 // curve25519 from SUPERCOP 20130419 by D. J. Bernstein.

@@ -50,17 +54,11 @@ func feCopy(dst, src *fieldElement) {
 //
 // Preconditions: b in {0,1}.
 func feCSwap(f, g *fieldElement, b int32) {
-	var x fieldElement
 	b = -b
-	for i := range x {
-		x[i] = b & (f[i] ^ g[i])
-	}
-
 	for i := range f {
-		f[i] ^= x[i]
-	}
-	for i := range g {
-		g[i] ^= x[i]
+		t := b & (f[i] ^ g[i])
+		f[i] ^= t
+		g[i] ^= t
 	}
 }

@@ -75,12 +73,7 @@ func load3(in []byte) int64 {

 // load4 reads a 32-bit, little-endian value from in.
 func load4(in []byte) int64 {
-	var r int64
-	r = int64(in[0])
-	r |= int64(in[1]) << 8
-	r |= int64(in[2]) << 16
-	r |= int64(in[3]) << 24
-	return r
+	return int64(binary.LittleEndian.Uint32(in))
 }

 func feFromBytes(dst *fieldElement, src *[32]byte) {
@@ -3,7 +3,7 @@
 // license that can be found in the LICENSE file.

 // Package curve25519 provides an implementation of scalar multiplication on
-// the elliptic curve known as curve25519. See http://cr.yp.to/ecdh.html
+// the elliptic curve known as curve25519. See https://cr.yp.to/ecdh.html
 package curve25519

 // basePoint is the x coordinate of the generator of the curve.
@@ -3,33 +3,22 @@
 // license that can be found in the LICENSE file.

 // This code was translated into a form compatible with 6a from the public
-// domain sources in SUPERCOP: http://bench.cr.yp.to/supercop.html
+// domain sources in SUPERCOP: https://bench.cr.yp.to/supercop.html

 // +build amd64,!gccgo,!appengine

+#include "const_amd64.h"
+
 // func freeze(inout *[5]uint64)
-TEXT ·freeze(SB),7,$96-8
+TEXT ·freeze(SB),7,$0-8
 	MOVQ inout+0(FP), DI

-	MOVQ SP,R11
-	MOVQ $31,CX
-	NOTQ CX
-	ANDQ CX,SP
-	ADDQ $32,SP
-
-	MOVQ R11,0(SP)
-	MOVQ R12,8(SP)
-	MOVQ R13,16(SP)
-	MOVQ R14,24(SP)
-	MOVQ R15,32(SP)
-	MOVQ BX,40(SP)
-	MOVQ BP,48(SP)
 	MOVQ 0(DI),SI
 	MOVQ 8(DI),DX
 	MOVQ 16(DI),CX
 	MOVQ 24(DI),R8
 	MOVQ 32(DI),R9
-	MOVQ ·REDMASK51(SB),AX
+	MOVQ $REDMASK51,AX
 	MOVQ AX,R10
 	SUBQ $18,R10
 	MOVQ $3,R11
@@ -81,14 +70,4 @@ REDUCELOOP:
 	MOVQ CX,16(DI)
 	MOVQ R8,24(DI)
 	MOVQ R9,32(DI)
-	MOVQ 0(SP),R11
-	MOVQ 8(SP),R12
-	MOVQ 16(SP),R13
-	MOVQ 24(SP),R14
-	MOVQ 32(SP),R15
-	MOVQ 40(SP),BX
-	MOVQ 48(SP),BP
-	MOVQ R11,SP
-	MOVQ DI,AX
-	MOVQ SI,DX
 	RET
@@ -3,40 +3,28 @@
 // license that can be found in the LICENSE file.

 // This code was translated into a form compatible with 6a from the public
-// domain sources in SUPERCOP: http://bench.cr.yp.to/supercop.html
+// domain sources in SUPERCOP: https://bench.cr.yp.to/supercop.html

 // +build amd64,!gccgo,!appengine

+#include "const_amd64.h"
+
 // func mul(dest, a, b *[5]uint64)
-TEXT ·mul(SB),0,$128-24
+TEXT ·mul(SB),0,$16-24
 	MOVQ dest+0(FP), DI
 	MOVQ a+8(FP), SI
 	MOVQ b+16(FP), DX

-	MOVQ SP,R11
-	MOVQ $31,CX
-	NOTQ CX
-	ANDQ CX,SP
-	ADDQ $32,SP
-
-	MOVQ R11,0(SP)
-	MOVQ R12,8(SP)
-	MOVQ R13,16(SP)
-	MOVQ R14,24(SP)
-	MOVQ R15,32(SP)
-	MOVQ BX,40(SP)
-	MOVQ BP,48(SP)
-	MOVQ DI,56(SP)
 	MOVQ DX,CX
 	MOVQ 24(SI),DX
 	IMUL3Q $19,DX,AX
-	MOVQ AX,64(SP)
+	MOVQ AX,0(SP)
 	MULQ 16(CX)
 	MOVQ AX,R8
 	MOVQ DX,R9
 	MOVQ 32(SI),DX
 	IMUL3Q $19,DX,AX
-	MOVQ AX,72(SP)
+	MOVQ AX,8(SP)
 	MULQ 8(CX)
 	ADDQ AX,R8
 	ADCQ DX,R9
@@ -111,11 +99,11 @@ TEXT ·mul(SB),0,$128-24
 	MULQ 8(CX)
 	ADDQ AX,BX
 	ADCQ DX,BP
-	MOVQ 64(SP),AX
+	MOVQ 0(SP),AX
 	MULQ 24(CX)
 	ADDQ AX,R10
 	ADCQ DX,R11
-	MOVQ 64(SP),AX
+	MOVQ 0(SP),AX
 	MULQ 32(CX)
 	ADDQ AX,R12
 	ADCQ DX,R13
@@ -123,19 +111,19 @@ TEXT ·mul(SB),0,$128-24
 	MULQ 0(CX)
 	ADDQ AX,BX
 	ADCQ DX,BP
-	MOVQ 72(SP),AX
+	MOVQ 8(SP),AX
 	MULQ 16(CX)
 	ADDQ AX,R10
 	ADCQ DX,R11
-	MOVQ 72(SP),AX
+	MOVQ 8(SP),AX
 	MULQ 24(CX)
 	ADDQ AX,R12
 	ADCQ DX,R13
-	MOVQ 72(SP),AX
+	MOVQ 8(SP),AX
 	MULQ 32(CX)
 	ADDQ AX,R14
 	ADCQ DX,R15
-	MOVQ ·REDMASK51(SB),SI
+	MOVQ $REDMASK51,SI
 	SHLQ $13,R9:R8
 	ANDQ SI,R8
 	SHLQ $13,R11:R10
@@ -178,14 +166,4 @@ TEXT ·mul(SB),0,$128-24
 	MOVQ R9,16(DI)
 	MOVQ AX,24(DI)
 	MOVQ R10,32(DI)
-	MOVQ 0(SP),R11
-	MOVQ 8(SP),R12
-	MOVQ 16(SP),R13
-	MOVQ 24(SP),R14
-	MOVQ 32(SP),R15
-	MOVQ 40(SP),BX
-	MOVQ 48(SP),BP
-	MOVQ R11,SP
-	MOVQ DI,AX
-	MOVQ SI,DX
 	RET
@@ -3,28 +3,17 @@
 // license that can be found in the LICENSE file.

 // This code was translated into a form compatible with 6a from the public
-// domain sources in SUPERCOP: http://bench.cr.yp.to/supercop.html
+// domain sources in SUPERCOP: https://bench.cr.yp.to/supercop.html

 // +build amd64,!gccgo,!appengine

+#include "const_amd64.h"
+
 // func square(out, in *[5]uint64)
-TEXT ·square(SB),7,$96-16
+TEXT ·square(SB),7,$0-16
 	MOVQ out+0(FP), DI
 	MOVQ in+8(FP), SI

-	MOVQ SP,R11
-	MOVQ $31,CX
-	NOTQ CX
-	ANDQ CX,SP
-	ADDQ $32, SP
-
-	MOVQ R11,0(SP)
-	MOVQ R12,8(SP)
-	MOVQ R13,16(SP)
-	MOVQ R14,24(SP)
-	MOVQ R15,32(SP)
-	MOVQ BX,40(SP)
-	MOVQ BP,48(SP)
 	MOVQ 0(SI),AX
 	MULQ 0(SI)
 	MOVQ AX,CX
@@ -97,7 +86,7 @@ TEXT ·square(SB),7,$96-16
 	MULQ 32(SI)
 	ADDQ AX,R13
 	ADCQ DX,R14
-	MOVQ ·REDMASK51(SB),SI
+	MOVQ $REDMASK51,SI
 	SHLQ $13,R8:CX
 	ANDQ SI,CX
 	SHLQ $13,R10:R9
@@ -140,14 +129,4 @@ TEXT ·square(SB),7,$96-16
 	MOVQ R9,16(DI)
 	MOVQ AX,24(DI)
 	MOVQ R10,32(DI)
-	MOVQ 0(SP),R11
-	MOVQ 8(SP),R12
-	MOVQ 16(SP),R13
-	MOVQ 24(SP),R14
-	MOVQ 32(SP),R15
-	MOVQ 40(SP),BX
-	MOVQ 48(SP),BP
-	MOVQ R11,SP
-	MOVQ DI,AX
-	MOVQ SI,DX
 	RET
@@ -0,0 +1,181 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package ed25519 implements the Ed25519 signature algorithm. See
+// https://ed25519.cr.yp.to/.
+//
+// These functions are also compatible with the “Ed25519” function defined in
+// https://tools.ietf.org/html/draft-irtf-cfrg-eddsa-05.
+package ed25519
+
+// This code is a port of the public domain, “ref10” implementation of ed25519
+// from SUPERCOP.
+
+import (
+	"crypto"
+	cryptorand "crypto/rand"
+	"crypto/sha512"
+	"crypto/subtle"
+	"errors"
+	"io"
+	"strconv"
+
+	"golang.org/x/crypto/ed25519/internal/edwards25519"
+)
+
+const (
+	// PublicKeySize is the size, in bytes, of public keys as used in this package.
+	PublicKeySize = 32
+	// PrivateKeySize is the size, in bytes, of private keys as used in this package.
+	PrivateKeySize = 64
+	// SignatureSize is the size, in bytes, of signatures generated and verified by this package.
+	SignatureSize = 64
+)
+
+// PublicKey is the type of Ed25519 public keys.
+type PublicKey []byte
+
+// PrivateKey is the type of Ed25519 private keys. It implements crypto.Signer.
+type PrivateKey []byte
+
+// Public returns the PublicKey corresponding to priv.
+func (priv PrivateKey) Public() crypto.PublicKey {
+	publicKey := make([]byte, PublicKeySize)
+	copy(publicKey, priv[32:])
+	return PublicKey(publicKey)
+}
+
+// Sign signs the given message with priv.
+// Ed25519 performs two passes over messages to be signed and therefore cannot
+// handle pre-hashed messages. Thus opts.HashFunc() must return zero to
+// indicate the message hasn't been hashed. This can be achieved by passing
+// crypto.Hash(0) as the value for opts.
+func (priv PrivateKey) Sign(rand io.Reader, message []byte, opts crypto.SignerOpts) (signature []byte, err error) {
+	if opts.HashFunc() != crypto.Hash(0) {
+		return nil, errors.New("ed25519: cannot sign hashed message")
+	}
+
+	return Sign(priv, message), nil
+}
+
+// GenerateKey generates a public/private key pair using entropy from rand.
+// If rand is nil, crypto/rand.Reader will be used.
+func GenerateKey(rand io.Reader) (publicKey PublicKey, privateKey PrivateKey, err error) {
+	if rand == nil {
+		rand = cryptorand.Reader
+	}
+
+	privateKey = make([]byte, PrivateKeySize)
+	publicKey = make([]byte, PublicKeySize)
+	_, err = io.ReadFull(rand, privateKey[:32])
+	if err != nil {
+		return nil, nil, err
+	}
+
+	digest := sha512.Sum512(privateKey[:32])
+	digest[0] &= 248
+	digest[31] &= 127
+	digest[31] |= 64
+
+	var A edwards25519.ExtendedGroupElement
+	var hBytes [32]byte
+	copy(hBytes[:], digest[:])
+	edwards25519.GeScalarMultBase(&A, &hBytes)
+	var publicKeyBytes [32]byte
+	A.ToBytes(&publicKeyBytes)
+
+	copy(privateKey[32:], publicKeyBytes[:])
+	copy(publicKey, publicKeyBytes[:])
+
+	return publicKey, privateKey, nil
+}
+
+// Sign signs the message with privateKey and returns a signature. It will
+// panic if len(privateKey) is not PrivateKeySize.
+func Sign(privateKey PrivateKey, message []byte) []byte {
+	if l := len(privateKey); l != PrivateKeySize {
+		panic("ed25519: bad private key length: " + strconv.Itoa(l))
+	}
+
+	h := sha512.New()
+	h.Write(privateKey[:32])
+
+	var digest1, messageDigest, hramDigest [64]byte
+	var expandedSecretKey [32]byte
+	h.Sum(digest1[:0])
+	copy(expandedSecretKey[:], digest1[:])
+	expandedSecretKey[0] &= 248
+	expandedSecretKey[31] &= 63
+	expandedSecretKey[31] |= 64
+
+	h.Reset()
+	h.Write(digest1[32:])
+	h.Write(message)
+	h.Sum(messageDigest[:0])
+
+	var messageDigestReduced [32]byte
+	edwards25519.ScReduce(&messageDigestReduced, &messageDigest)
+	var R edwards25519.ExtendedGroupElement
+	edwards25519.GeScalarMultBase(&R, &messageDigestReduced)
+
+	var encodedR [32]byte
+	R.ToBytes(&encodedR)
+
+	h.Reset()
+	h.Write(encodedR[:])
+	h.Write(privateKey[32:])
+	h.Write(message)
+	h.Sum(hramDigest[:0])
+	var hramDigestReduced [32]byte
+	edwards25519.ScReduce(&hramDigestReduced, &hramDigest)
+
+	var s [32]byte
+	edwards25519.ScMulAdd(&s, &hramDigestReduced, &expandedSecretKey, &messageDigestReduced)
+
+	signature := make([]byte, SignatureSize)
+	copy(signature[:], encodedR[:])
+	copy(signature[32:], s[:])
+
+	return signature
+}
+
+// Verify reports whether sig is a valid signature of message by publicKey. It
+// will panic if len(publicKey) is not PublicKeySize.
+func Verify(publicKey PublicKey, message, sig []byte) bool {
+	if l := len(publicKey); l != PublicKeySize {
+		panic("ed25519: bad public key length: " + strconv.Itoa(l))
+	}
+
+	if len(sig) != SignatureSize || sig[63]&224 != 0 {
+		return false
+	}
+
+	var A edwards25519.ExtendedGroupElement
+	var publicKeyBytes [32]byte
+	copy(publicKeyBytes[:], publicKey)
+	if !A.FromBytes(&publicKeyBytes) {
+		return false
+	}
+	edwards25519.FeNeg(&A.X, &A.X)
+	edwards25519.FeNeg(&A.T, &A.T)
+
+	h := sha512.New()
+	h.Write(sig[:32])
+	h.Write(publicKey[:])
+	h.Write(message)
+	var digest [64]byte
+	h.Sum(digest[:0])
+
+	var hReduced [32]byte
+	edwards25519.ScReduce(&hReduced, &digest)
+
+	var R edwards25519.ProjectiveGroupElement
+	var b [32]byte
+	copy(b[:], sig[32:])
+	edwards25519.GeDoubleScalarMultVartime(&R, &hReduced, &A, &b)
+
+	var checkR [32]byte
+	R.ToBytes(&checkR)
+	return subtle.ConstantTimeCompare(sig[:32], checkR[:]) == 1
+}
@@ -22,6 +22,7 @@ const (
 	CertAlgoECDSA256v01 = "ecdsa-sha2-nistp256-cert-v01@openssh.com"
 	CertAlgoECDSA384v01 = "ecdsa-sha2-nistp384-cert-v01@openssh.com"
 	CertAlgoECDSA521v01 = "ecdsa-sha2-nistp521-cert-v01@openssh.com"
+	CertAlgoED25519v01  = "ssh-ed25519-cert-v01@openssh.com"
 )

 // Certificate types distinguish between host and user
@@ -250,10 +251,18 @@ type CertChecker struct {
 	// for user certificates.
 	SupportedCriticalOptions []string

-	// IsAuthority should return true if the key is recognized as
-	// an authority. This allows for certificates to be signed by other
-	// certificates.
-	IsAuthority func(auth PublicKey) bool
+	// IsUserAuthority should return true if the key is recognized as an
+	// authority for the given user certificate. This allows for
+	// certificates to be signed by other certificates. This must be set
+	// if this CertChecker will be checking user certificates.
+	IsUserAuthority func(auth PublicKey) bool
+
+	// IsHostAuthority should report whether the key is recognized as
+	// an authority for this host. This allows for certificates to be
+	// signed by other keys, and for those other keys to only be valid
+	// signers for particular hostnames. This must be set if this
+	// CertChecker will be checking host certificates.
+	IsHostAuthority func(auth PublicKey, address string) bool

 	// Clock is used for verifying time stamps. If nil, time.Now
 	// is used.
@@ -267,7 +276,7 @@ type CertChecker struct {
 	// HostKeyFallback is called when CertChecker.CheckHostKey encounters a
 	// public key that is not a certificate. It must implement host key
 	// validation or else, if nil, all such keys are rejected.
-	HostKeyFallback func(addr string, remote net.Addr, key PublicKey) error
+	HostKeyFallback HostKeyCallback

 	// IsRevoked is called for each certificate so that revocation checking
 	// can be implemented. It should return true if the given certificate
@@ -289,8 +298,17 @@ func (c *CertChecker) CheckHostKey(addr string, remote net.Addr, key PublicKey)
 	if cert.CertType != HostCert {
 		return fmt.Errorf("ssh: certificate presented as a host key has type %d", cert.CertType)
 	}
+	if !c.IsHostAuthority(cert.SignatureKey, addr) {
+		return fmt.Errorf("ssh: no authorities for hostname: %v", addr)
+	}

-	return c.CheckCert(addr, cert)
+	hostname, _, err := net.SplitHostPort(addr)
+	if err != nil {
+		return err
+	}
+
+	// Pass hostname only as principal for host certificates (consistent with OpenSSH)
+	return c.CheckCert(hostname, cert)
 }

 // Authenticate checks a user certificate. Authenticate can be used as
@@ -307,6 +325,9 @@ func (c *CertChecker) Authenticate(conn ConnMetadata, pubKey PublicKey) (*Permis
 	if cert.CertType != UserCert {
 		return nil, fmt.Errorf("ssh: cert has type %d", cert.CertType)
 	}
+	if !c.IsUserAuthority(cert.SignatureKey) {
+		return nil, fmt.Errorf("ssh: certificate signed by unrecognized authority")
+	}

 	if err := c.CheckCert(conn.User(), cert); err != nil {
 		return nil, err
@@ -355,10 +376,6 @@ func (c *CertChecker) CheckCert(principal string, cert *Certificate) error {
 		}
 	}

-	if !c.IsAuthority(cert.SignatureKey) {
-		return fmt.Errorf("ssh: certificate signed by unrecognized authority")
-	}
-
 	clock := c.Clock
 	if clock == nil {
 		clock = time.Now
@@ -401,6 +418,7 @@ var certAlgoNames = map[string]string{
 	KeyAlgoECDSA256: CertAlgoECDSA256v01,
 	KeyAlgoECDSA384: CertAlgoECDSA384v01,
 	KeyAlgoECDSA521: CertAlgoECDSA521v01,
+	KeyAlgoED25519:  CertAlgoED25519v01,
 }

 // certToPrivAlgo returns the underlying algorithm for a certificate algorithm.
@@ -459,7 +477,7 @@ func (c *Certificate) Marshal() []byte {
 func (c *Certificate) Type() string {
 	algo, ok := certAlgoNames[c.Key.Type()]
 	if !ok {
-		panic("unknown cert key type")
+		panic("unknown cert key type " + c.Key.Type())
 	}
 	return algo
 }
@@ -67,6 +67,8 @@ type Channel interface {
 	// boolean, otherwise the return value will be false. Channel
 	// requests are out-of-band messages so they may be sent even
 	// if the data stream is closed or blocked by flow control.
+	// If the channel is closed before a reply is returned, io.EOF
+	// is returned.
 	SendRequest(name string, wantReply bool, payload []byte) (bool, error)

 	// Stderr returns an io.ReadWriter that writes to this channel
@@ -217,7 +219,7 @@ func (c *channel) writePacket(packet []byte) error {

 func (c *channel) sendMessage(msg interface{}) error {
 	if debugMux {
-		log.Printf("send %d: %#v", c.mux.chanList.offset, msg)
+		log.Printf("send(%d): %#v", c.mux.chanList.offset, msg)
 	}

 	p := Marshal(msg)
@@ -371,7 +373,7 @@ func (c *channel) close() {
 	close(c.msg)
 	close(c.incomingRequests)
 	c.writeMu.Lock()
-	// This is not necesary for a normal channel teardown, but if
+	// This is not necessary for a normal channel teardown, but if
 	// there was another error, it is.
 	c.sentClose = true
 	c.writeMu.Unlock()
@@ -459,8 +461,8 @@ func (m *mux) newChannel(chanType string, direction channelDirection, extraData
 		pending:          newBuffer(),
 		extPending:       newBuffer(),
 		direction:        direction,
-		incomingRequests: make(chan *Request, 16),
-		msg:              make(chan interface{}, 16),
+		incomingRequests: make(chan *Request, chanSize),
+		msg:              make(chan interface{}, chanSize),
 		chanType:         chanType,
 		extraData:        extraData,
 		mux:              m,
@@ -7,6 +7,7 @@ package ssh
 import (
 	"crypto/aes"
 	"crypto/cipher"
+	"crypto/des"
 	"crypto/rc4"
 	"crypto/subtle"
 	"encoding/binary"
@@ -115,9 +116,15 @@ var cipherModes = map[string]*streamCipherMode{
 	// should invest a cleaner way to do this.
 	gcmCipherID: {16, 12, 0, nil},

-	// insecure cipher, see http://www.isg.rhul.ac.uk/~kp/SandPfinal.pdf
-	// uncomment below to enable it.
-	// aes128cbcID: {16, aes.BlockSize, 0, nil},
+	// CBC mode is insecure and so is not included in the default config.
+	// (See http://www.isg.rhul.ac.uk/~kp/SandPfinal.pdf). If absolutely
+	// needed, it's possible to specify a custom Config to enable it.
+	// You should expect that an active attacker can recover plaintext if
+	// you do.
+	aes128cbcID: {16, aes.BlockSize, 0, nil},
+
+	// 3des-cbc is insecure and is disabled by default.
+	tripledescbcID: {24, des.BlockSize, 0, nil},
 }

 // prefixLen is the length of the packet prefix that contains the packet length
@@ -128,6 +135,7 @@ const prefixLen = 5
 type streamPacketCipher struct {
 	mac    hash.Hash
 	cipher cipher.Stream
+	etm    bool

 	// The following members are to avoid per-packet allocations.
 	prefix      [prefixLen]byte
@@ -143,7 +151,14 @@ func (s *streamPacketCipher) readPacket(seqNum uint32, r io.Reader) ([]byte, err
 		return nil, err
 	}

-	s.cipher.XORKeyStream(s.prefix[:], s.prefix[:])
+	var encryptedPaddingLength [1]byte
+	if s.mac != nil && s.etm {
+		copy(encryptedPaddingLength[:], s.prefix[4:5])
+		s.cipher.XORKeyStream(s.prefix[4:5], s.prefix[4:5])
+	} else {
+		s.cipher.XORKeyStream(s.prefix[:], s.prefix[:])
+	}
+
 	length := binary.BigEndian.Uint32(s.prefix[0:4])
 	paddingLength := uint32(s.prefix[4])

@@ -152,7 +167,12 @@ func (s *streamPacketCipher) readPacket(seqNum uint32, r io.Reader) ([]byte, err
 		s.mac.Reset()
 		binary.BigEndian.PutUint32(s.seqNumBytes[:], seqNum)
 		s.mac.Write(s.seqNumBytes[:])
-		s.mac.Write(s.prefix[:])
+		if s.etm {
+			s.mac.Write(s.prefix[:4])
+			s.mac.Write(encryptedPaddingLength[:])
+		} else {
+			s.mac.Write(s.prefix[:])
+		}
 		macSize = uint32(s.mac.Size())
 	}

@@ -177,10 +197,17 @@ func (s *streamPacketCipher) readPacket(seqNum uint32, r io.Reader) ([]byte, err
 	}
 	mac := s.packetData[length-1:]
 	data := s.packetData[:length-1]
+
+	if s.mac != nil && s.etm {
+		s.mac.Write(data)
+	}
+
 	s.cipher.XORKeyStream(data, data)

 	if s.mac != nil {
-		s.mac.Write(data)
+		if !s.etm {
+			s.mac.Write(data)
+		}
 		s.macResult = s.mac.Sum(s.macResult[:0])
 		if subtle.ConstantTimeCompare(s.macResult, mac) != 1 {
 			return nil, errors.New("ssh: MAC failure")
@@ -196,7 +223,13 @@ func (s *streamPacketCipher) writePacket(seqNum uint32, w io.Writer, rand io.Rea
 		return errors.New("ssh: packet too large")
 	}

-	paddingLength := packetSizeMultiple - (prefixLen+len(packet))%packetSizeMultiple
+	aadlen := 0
+	if s.mac != nil && s.etm {
+		// packet length is not encrypted for EtM modes
+		aadlen = 4
+	}
+
+	paddingLength := packetSizeMultiple - (prefixLen+len(packet)-aadlen)%packetSizeMultiple
 	if paddingLength < 4 {
 		paddingLength += packetSizeMultiple
 	}
@@ -213,15 +246,37 @@ func (s *streamPacketCipher) writePacket(seqNum uint32, w io.Writer, rand io.Rea
 		s.mac.Reset()
 		binary.BigEndian.PutUint32(s.seqNumBytes[:], seqNum)
 		s.mac.Write(s.seqNumBytes[:])
+
+		if s.etm {
+			// For EtM algorithms, the packet length must stay unencrypted,
+			// but the following data (padding length) must be encrypted
+			s.cipher.XORKeyStream(s.prefix[4:5], s.prefix[4:5])
+		}
+
 		s.mac.Write(s.prefix[:])
+
+		if !s.etm {
+			// For non-EtM algorithms, the algorithm is applied on unencrypted data
+			s.mac.Write(packet)
+			s.mac.Write(padding)
+		}
+	}
+
+	if !(s.mac != nil && s.etm) {
+		// For EtM algorithms, the padding length has already been encrypted
+		// and the packet length must remain unencrypted
+		s.cipher.XORKeyStream(s.prefix[:], s.prefix[:])
+	}
+
+	s.cipher.XORKeyStream(packet, packet)
+	s.cipher.XORKeyStream(padding, padding)
+
+	if s.mac != nil && s.etm {
+		// For EtM algorithms, packet and padding must be encrypted
 		s.mac.Write(packet)
 		s.mac.Write(padding)
 	}

-	s.cipher.XORKeyStream(s.prefix[:], s.prefix[:])
-	s.cipher.XORKeyStream(packet, packet)
-	s.cipher.XORKeyStream(padding, padding)
-
 	if _, err := w.Write(s.prefix[:]); err != nil {
 		return err
 	}
@@ -365,12 +420,7 @@ type cbcCipher struct {
 	oracleCamouflage uint32
 }

-func newAESCBCCipher(iv, key, macKey []byte, algs directionAlgorithms) (packetCipher, error) {
-	c, err := aes.NewCipher(key)
-	if err != nil {
-		return nil, err
-	}
-
+func newCBCCipher(c cipher.Block, iv, key, macKey []byte, algs directionAlgorithms) (packetCipher, error) {
 	cbc := &cbcCipher{
 		mac:        macModes[algs.MAC].new(macKey),
 		decrypter:  cipher.NewCBCDecrypter(c, iv),
@@ -384,6 +434,34 @@ func newAESCBCCipher(iv, key, macKey []byte, algs directionAlgorithms) (packetCi
 	return cbc, nil
 }

+func newAESCBCCipher(iv, key, macKey []byte, algs directionAlgorithms) (packetCipher, error) {
+	c, err := aes.NewCipher(key)
+	if err != nil {
+		return nil, err
+	}
+
+	cbc, err := newCBCCipher(c, iv, key, macKey, algs)
+	if err != nil {
+		return nil, err
+	}
+
+	return cbc, nil
+}
+
+func newTripleDESCBCCipher(iv, key, macKey []byte, algs directionAlgorithms) (packetCipher, error) {
+	c, err := des.NewTripleDESCipher(key)
+	if err != nil {
+		return nil, err
+	}
+
+	cbc, err := newCBCCipher(c, iv, key, macKey, algs)
+	if err != nil {
+		return nil, err
+	}
+
+	return cbc, nil
+}
+
 func maxUInt32(a, b int) uint32 {
 	if a > b {
 		return uint32(a)
@@ -5,14 +5,16 @@
 package ssh

 import (
+	"bytes"
 	"errors"
 	"fmt"
 	"net"
 	"sync"
+	"time"
 )

 // Client implements a traditional SSH client that supports shells,
-// subprocesses, port forwarding and tunneled dialing.
+// subprocesses, TCP port/streamlocal forwarding and tunneled dialing.
 type Client struct {
 	Conn

@@ -39,7 +41,7 @@ func (c *Client) HandleChannelOpen(channelType string) <-chan NewChannel {
 		return nil
 	}

-	ch = make(chan NewChannel, 16)
+	ch = make(chan NewChannel, chanSize)
 	c.channelHandlers[channelType] = ch
 	return ch
 }
@@ -58,6 +60,7 @@ func NewClient(c Conn, chans <-chan NewChannel, reqs <-chan *Request) *Client {
 		conn.forwards.closeAll()
 	}()
 	go conn.forwards.handleChannels(conn.HandleChannelOpen("forwarded-tcpip"))
+	go conn.forwards.handleChannels(conn.HandleChannelOpen("forwarded-streamlocal@openssh.com"))
 	return conn
 }

@@ -67,6 +70,11 @@ func NewClient(c Conn, chans <-chan NewChannel, reqs <-chan *Request) *Client {
 func NewClientConn(c net.Conn, addr string, config *ClientConfig) (Conn, <-chan NewChannel, <-chan *Request, error) {
 	fullConf := *config
 	fullConf.SetDefaults()
+	if fullConf.HostKeyCallback == nil {
+		c.Close()
+		return nil, nil, nil, errors.New("ssh: must specify HostKeyCallback")
+	}
+
 	conn := &connection{
 		sshConn: sshConn{conn: c},
 	}
@@ -96,19 +104,11 @@ func (c *connection) clientHandshake(dialAddress string, config *ClientConfig) e
 	c.transport = newClientTransport(
 		newTransport(c.sshConn.conn, config.Rand, true /* is client */),
 		c.clientVersion, c.serverVersion, config, dialAddress, c.sshConn.RemoteAddr())
-	if err := c.transport.requestKeyChange(); err != nil {
+	if err := c.transport.waitSession(); err != nil {
 		return err
 	}

-	if packet, err := c.transport.readPacket(); err != nil {
-		return err
-	} else if packet[0] != msgNewKeys {
-		return unexpectedMessageError(msgNewKeys, packet[0])
-	}
-
-	// We just did the key change, so the session ID is established.
 	c.sessionID = c.transport.getSessionID()
-
 	return c.clientAuthenticate(config)
 }

@@ -169,7 +169,7 @@ func (c *Client) handleChannelOpens(in <-chan NewChannel) {
 // to incoming channels and requests, use net.Dial with NewClientConn
 // instead.
 func Dial(network, addr string, config *ClientConfig) (*Client, error) {
-	conn, err := net.Dial(network, addr)
+	conn, err := net.DialTimeout(network, addr, config.Timeout)
 	if err != nil {
 		return nil, err
 	}
@@ -180,6 +180,13 @@ func Dial(network, addr string, config *ClientConfig) (*Client, error) {
 	return NewClient(c, chans, reqs), nil
 }

+// HostKeyCallback is the function type used for verifying server
+// keys.  A HostKeyCallback must return nil if the host key is OK, or
+// an error to reject it. It receives the hostname as passed to Dial
+// or NewClientConn. The remote address is the RemoteAddr of the
+// net.Conn underlying the the SSH connection.
+type HostKeyCallback func(hostname string, remote net.Addr, key PublicKey) error
+
 // A ClientConfig structure is used to configure a Client. It must not be
 // modified after having been passed to an SSH function.
 type ClientConfig struct {
@@ -195,10 +202,12 @@ type ClientConfig struct {
 	// be used during authentication.
 	Auth []AuthMethod

-	// HostKeyCallback, if not nil, is called during the cryptographic
-	// handshake to validate the server's host key. A nil HostKeyCallback
-	// implies that all host keys are accepted.
-	HostKeyCallback func(hostname string, remote net.Addr, key PublicKey) error
+	// HostKeyCallback is called during the cryptographic
+	// handshake to validate the server's host key. The client
+	// configuration must supply this callback for the connection
+	// to succeed. The functions InsecureIgnoreHostKey or
+	// FixedHostKey can be used for simplistic host key checks.
+	HostKeyCallback HostKeyCallback

 	// ClientVersion contains the version identification string that will
 	// be used for the connection. If empty, a reasonable default is used.
@@ -210,4 +219,39 @@ type ClientConfig struct {
 	// string returned from PublicKey.Type method may be used, or
 	// any of the CertAlgoXxxx and KeyAlgoXxxx constants.
 	HostKeyAlgorithms []string
+
+	// Timeout is the maximum amount of time for the TCP connection to establish.
+	//
+	// A Timeout of zero means no timeout.
+	Timeout time.Duration
+}
+
+// InsecureIgnoreHostKey returns a function that can be used for
+// ClientConfig.HostKeyCallback to accept any host key. It should
+// not be used for production code.
+func InsecureIgnoreHostKey() HostKeyCallback {
+	return func(hostname string, remote net.Addr, key PublicKey) error {
+		return nil
+	}
+}
+
+type fixedHostKey struct {
+	key PublicKey
+}
+
+func (f *fixedHostKey) check(hostname string, remote net.Addr, key PublicKey) error {
+	if f.key == nil {
+		return fmt.Errorf("ssh: required host key was nil")
+	}
+	if !bytes.Equal(key.Marshal(), f.key.Marshal()) {
+		return fmt.Errorf("ssh: host key mismatch")
+	}
+	return nil
+}
+
+// FixedHostKey returns a function for use in
+// ClientConfig.HostKeyCallback to accept only a specific host key.
+func FixedHostKey(key PublicKey) HostKeyCallback {
+	hk := &fixedHostKey{key}
+	return hk.check
 }
@@ -30,8 +30,10 @@ func (c *connection) clientAuthenticate(config *ClientConfig) error {
 	// then any untried methods suggested by the server.
 	tried := make(map[string]bool)
 	var lastMethods []string
+
+	sessionID := c.transport.getSessionID()
 	for auth := AuthMethod(new(noneAuth)); auth != nil; {
-		ok, methods, err := auth.auth(c.transport.getSessionID(), config.User, c.transport, config.Rand)
+		ok, methods, err := auth.auth(sessionID, config.User, c.transport, config.Rand)
 		if err != nil {
 			return err
 		}
@@ -177,31 +179,26 @@ func (cb publicKeyCallback) method() string {
 }

 func (cb publicKeyCallback) auth(session []byte, user string, c packetConn, rand io.Reader) (bool, []string, error) {
-	// Authentication is performed in two stages. The first stage sends an
-	// enquiry to test if each key is acceptable to the remote. The second
-	// stage attempts to authenticate with the valid keys obtained in the
-	// first stage.
+	// Authentication is performed by sending an enquiry to test if a key is
+	// acceptable to the remote. If the key is acceptable, the client will
+	// attempt to authenticate with the valid key.  If not the client will repeat
+	// the process with the remaining keys.

 	signers, err := cb()
 	if err != nil {
 		return false, nil, err
 	}
-	var validKeys []Signer
-	for _, signer := range signers {
-		if ok, err := validateKey(signer.PublicKey(), user, c); ok {
-			validKeys = append(validKeys, signer)
-		} else {
-			if err != nil {
-				return false, nil, err
-			}
-		}
-	}
-
-	// methods that may continue if this auth is not successful.
 	var methods []string
-	for _, signer := range validKeys {
-		pub := signer.PublicKey()
+	for _, signer := range signers {
+		ok, err := validateKey(signer.PublicKey(), user, c)
+		if err != nil {
+			return false, nil, err
+		}
+		if !ok {
+			continue
+		}

+		pub := signer.PublicKey()
 		pubKey := pub.Marshal()
 		sign, err := signer.Sign(rand, buildDataSignedForAuth(session, userAuthRequestMsg{
 			User:    user,
@@ -234,13 +231,29 @@ func (cb publicKeyCallback) auth(session []byte, user string, c packetConn, rand
 		if err != nil {
 			return false, nil, err
 		}
-		if success {
+
+		// If authentication succeeds or the list of available methods does not
+		// contain the "publickey" method, do not attempt to authenticate with any
+		// other keys.  According to RFC 4252 Section 7, the latter can occur when
+		// additional authentication methods are required.
+		if success || !containsMethod(methods, cb.method()) {
 			return success, methods, err
 		}
 	}
+
 	return false, methods, nil
 }

+func containsMethod(methods []string, method string) bool {
+	for _, m := range methods {
+		if m == method {
+			return true
+		}
+	}
+
+	return false
+}
+
 // validateKey validates the key provided is acceptable to the server.
 func validateKey(key PublicKey, user string, c packetConn) (bool, error) {
 	pubKey := key.Marshal()
@@ -321,8 +334,6 @@ func handleAuthResponse(c packetConn) (bool, []string, error) {
 			return false, msg.Methods, nil
 		case msgUserAuthSuccess:
 			return true, nil, nil
-		case msgDisconnect:
-			return false, nil, io.EOF
 		default:
 			return false, nil, unexpectedMessageError(msgUserAuthSuccess, packet[0])
 		}
@@ -439,3 +450,37 @@ func (cb KeyboardInteractiveChallenge) auth(session []byte, user string, c packe
 		}
 	}
 }
+
+type retryableAuthMethod struct {
+	authMethod AuthMethod
+	maxTries   int
+}
+
+func (r *retryableAuthMethod) auth(session []byte, user string, c packetConn, rand io.Reader) (ok bool, methods []string, err error) {
+	for i := 0; r.maxTries <= 0 || i < r.maxTries; i++ {
+		ok, methods, err = r.authMethod.auth(session, user, c, rand)
+		if ok || err != nil { // either success or error terminate
+			return ok, methods, err
+		}
+	}
+	return ok, methods, err
+}
+
+func (r *retryableAuthMethod) method() string {
+	return r.authMethod.method()
+}
+
+// RetryableAuthMethod is a decorator for other auth methods enabling them to
+// be retried up to maxTries before considering that AuthMethod itself failed.
+// If maxTries is <= 0, will retry indefinitely
+//
+// This is useful for interactive clients using challenge/response type
+// authentication (e.g. Keyboard-Interactive, Password, etc) where the user
+// could mistype their response resulting in the server issuing a
+// SSH_MSG_USERAUTH_FAILURE (rfc4252 #8 [password] and rfc4256 #3.4
+// [keyboard-interactive]); Without this decorator, the non-retryable
+// AuthMethod would be removed from future consideration, and never tried again
+// (and so the user would never be able to retry their entry).
+func RetryableAuthMethod(auth AuthMethod, maxTries int) AuthMethod {
+	return &retryableAuthMethod{authMethod: auth, maxTries: maxTries}
+}
@@ -9,6 +9,7 @@ import (
 	"crypto/rand"
 	"fmt"
 	"io"
+	"math"
 	"sync"

 	_ "crypto/sha1"
@@ -40,21 +41,23 @@ var supportedKexAlgos = []string{
 	kexAlgoDH14SHA1, kexAlgoDH1SHA1,
 }

-// supportedKexAlgos specifies the supported host-key algorithms (i.e. methods
+// supportedHostKeyAlgos specifies the supported host-key algorithms (i.e. methods
 // of authenticating servers) in preference order.
 var supportedHostKeyAlgos = []string{
 	CertAlgoRSAv01, CertAlgoDSAv01, CertAlgoECDSA256v01,
-	CertAlgoECDSA384v01, CertAlgoECDSA521v01,
+	CertAlgoECDSA384v01, CertAlgoECDSA521v01, CertAlgoED25519v01,

 	KeyAlgoECDSA256, KeyAlgoECDSA384, KeyAlgoECDSA521,
 	KeyAlgoRSA, KeyAlgoDSA,
+
+	KeyAlgoED25519,
 }

 // supportedMACs specifies a default set of MAC algorithms in preference order.
 // This is based on RFC 4253, section 6.4, but with hmac-md5 variants removed
 // because they have reached the end of their useful life.
 var supportedMACs = []string{
-	"hmac-sha2-256", "hmac-sha1", "hmac-sha1-96",
+	"hmac-sha2-256-etm@openssh.com", "hmac-sha2-256", "hmac-sha1", "hmac-sha1-96",
 }

 var supportedCompressions = []string{compressionNone}
@@ -102,6 +105,21 @@ type directionAlgorithms struct {
 	Compression string
 }

+// rekeyBytes returns a rekeying intervals in bytes.
+func (a *directionAlgorithms) rekeyBytes() int64 {
+	// According to RFC4344 block ciphers should rekey after
+	// 2^(BLOCKSIZE/4) blocks. For all AES flavors BLOCKSIZE is
+	// 128.
+	switch a.Cipher {
+	case "aes128-ctr", "aes192-ctr", "aes256-ctr", gcmCipherID, aes128cbcID:
+		return 16 * (1 << 32)
+
+	}
+
+	// For others, stick with RFC4253 recommendation to rekey after 1 Gb of data.
+	return 1 << 30
+}
+
 type algorithms struct {
 	kex     string
 	hostKey string
@@ -169,7 +187,7 @@ type Config struct {

 	// The maximum number of bytes sent or received after which a
 	// new key is negotiated. It must be at least 256. If
-	// unspecified, 1 gigabyte is used.
+	// unspecified, a size suitable for the chosen cipher is used.
 	RekeyThreshold uint64

 	// The allowed key exchanges algorithms. If unspecified then a
@@ -213,11 +231,12 @@ func (c *Config) SetDefaults() {
 	}

 	if c.RekeyThreshold == 0 {
-		// RFC 4253, section 9 suggests rekeying after 1G.
-		c.RekeyThreshold = 1 << 30
-	}
-	if c.RekeyThreshold < minRekeyThreshold {
+		// cipher specific default
+	} else if c.RekeyThreshold < minRekeyThreshold {
 		c.RekeyThreshold = minRekeyThreshold
+	} else if c.RekeyThreshold >= math.MaxInt64 {
+		// Avoid weirdness if somebody uses -1 as a threshold.
+		c.RekeyThreshold = math.MaxInt64
 	}
 }

@@ -23,10 +23,9 @@ func (e *OpenChannelError) Error() string {
 // ConnMetadata holds metadata for the connection.
 type ConnMetadata interface {
 	// User returns the user ID for this connection.
-	// It is empty if no authentication is used.
 	User() string

-	// SessionID returns the sesson hash, also denoted by H.
+	// SessionID returns the session hash, also denoted by H.
 	SessionID() []byte

 	// ClientVersion returns the client's version string as hashed
@@ -14,5 +14,8 @@ others.
 References:
  [PROTOCOL.certkeys]: http://cvsweb.openbsd.org/cgi-bin/cvsweb/src/usr.bin/ssh/PROTOCOL.certkeys?rev=HEAD
  [SSH-PARAMETERS]:    http://www.iana.org/assignments/ssh-parameters/ssh-parameters.xml#ssh-parameters-1
+
+This package does not fall under the stability promise of the Go language itself,
+so its API may be changed when pressing needs arise.
 */
 package ssh
@@ -19,6 +19,11 @@ import (
 // messages are wrong when using ECDH.
 const debugHandshake = false

+// chanSize sets the amount of buffering SSH connections. This is
+// primarily for testing: setting chanSize=0 uncovers deadlocks more
+// quickly.
+const chanSize = 16
+
 // keyingTransport is a packet based transport that supports key
 // changes. It need not be thread-safe. It should pass through
 // msgNewKeys in both directions.
@@ -29,25 +34,6 @@ type keyingTransport interface {
 	// direction will be effected if a msgNewKeys message is sent
 	// or received.
 	prepareKeyChange(*algorithms, *kexResult) error
-
-	// getSessionID returns the session ID. prepareKeyChange must
-	// have been called once.
-	getSessionID() []byte
-}
-
-// rekeyingTransport is the interface of handshakeTransport that we
-// (internally) expose to ClientConn and ServerConn.
-type rekeyingTransport interface {
-	packetConn
-
-	// requestKeyChange asks the remote side to change keys. All
-	// writes are blocked until the key change succeeds, which is
-	// signaled by reading a msgNewKeys.
-	requestKeyChange() error
-
-	// getSessionID returns the session ID. This is only valid
-	// after the first key change has completed.
-	getSessionID() []byte
 }

 // handshakeTransport implements rekeying on top of a keyingTransport
@@ -72,20 +58,42 @@ type handshakeTransport struct {
 	incoming  chan []byte
 	readError error

+	mu             sync.Mutex
+	writeError     error
+	sentInitPacket []byte
+	sentInitMsg    *kexInitMsg
+	pendingPackets [][]byte // Used when a key exchange is in progress.
+
+	// If the read loop wants to schedule a kex, it pings this
+	// channel, and the write loop will send out a kex
+	// message.
+	requestKex chan struct{}
+
+	// If the other side requests or confirms a kex, its kexInit
+	// packet is sent here for the write loop to find it.
+	startKex chan *pendingKex
+
 	// data for host key checking
-	hostKeyCallback func(hostname string, remote net.Addr, key PublicKey) error
+	hostKeyCallback HostKeyCallback
 	dialAddress     string
 	remoteAddr      net.Addr

-	readSinceKex uint64
+	// Algorithms agreed in the last key exchange.
+	algorithms *algorithms

-	// Protects the writing side of the connection
-	mu              sync.Mutex
-	cond            *sync.Cond
-	sentInitPacket  []byte
-	sentInitMsg     *kexInitMsg
-	writtenSinceKex uint64
-	writeError      error
+	readPacketsLeft uint32
+	readBytesLeft   int64
+
+	writePacketsLeft uint32
+	writeBytesLeft   int64
+
+	// The session ID or nil if first kex did not complete yet.
+	sessionID []byte
+}
+
+type pendingKex struct {
+	otherInit []byte
+	done      chan error
 }

 func newHandshakeTransport(conn keyingTransport, config *Config, clientVersion, serverVersion []byte) *handshakeTransport {
@@ -93,10 +101,17 @@ func newHandshakeTransport(conn keyingTransport, config *Config, clientVersion,
 		conn:          conn,
 		serverVersion: serverVersion,
 		clientVersion: clientVersion,
-		incoming:      make(chan []byte, 16),
-		config:        config,
+		incoming:      make(chan []byte, chanSize),
+		requestKex:    make(chan struct{}, 1),
+		startKex:      make(chan *pendingKex, 1),
+
+		config: config,
 	}
-	t.cond = sync.NewCond(&t.mu)
+	t.resetReadThresholds()
+	t.resetWriteThresholds()
+
+	// We always start with a mandatory key exchange.
+	t.requestKex <- struct{}{}
 	return t
 }

@@ -111,6 +126,7 @@ func newClientTransport(conn keyingTransport, clientVersion, serverVersion []byt
 		t.hostKeyAlgorithms = supportedHostKeyAlgos
 	}
 	go t.readLoop()
+	go t.kexLoop()
 	return t
 }

@@ -118,11 +134,26 @@ func newServerTransport(conn keyingTransport, clientVersion, serverVersion []byt
 	t := newHandshakeTransport(conn, &config.Config, clientVersion, serverVersion)
 	t.hostKeys = config.hostKeys
 	go t.readLoop()
+	go t.kexLoop()
 	return t
 }

 func (t *handshakeTransport) getSessionID() []byte {
-	return t.conn.getSessionID()
+	return t.sessionID
+}
+
+// waitSession waits for the session to be established. This should be
+// the first thing to call after instantiating handshakeTransport.
+func (t *handshakeTransport) waitSession() error {
+	p, err := t.readPacket()
+	if err != nil {
+		return err
+	}
+	if p[0] != msgNewKeys {
+		return fmt.Errorf("ssh: first packet should be msgNewKeys")
+	}
+
+	return nil
 }

 func (t *handshakeTransport) id() string {
@@ -132,6 +163,20 @@ func (t *handshakeTransport) id() string {
 	return "client"
 }

+func (t *handshakeTransport) printPacket(p []byte, write bool) {
+	action := "got"
+	if write {
+		action = "sent"
+	}
+
+	if p[0] == msgChannelData || p[0] == msgChannelExtendedData {
+		log.Printf("%s %s data (packet %d bytes)", t.id(), action, len(p))
+	} else {
+		msg, err := decode(p)
+		log.Printf("%s %s %T %v (%v)", t.id(), action, msg, msg, err)
+	}
+}
+
 func (t *handshakeTransport) readPacket() ([]byte, error) {
 	p, ok := <-t.incoming
 	if !ok {
@@ -141,8 +186,10 @@ func (t *handshakeTransport) readPacket() ([]byte, error) {
 }

 func (t *handshakeTransport) readLoop() {
+	first := true
 	for {
-		p, err := t.readOnePacket()
+		p, err := t.readOnePacket(first)
+		first = false
 		if err != nil {
 			t.readError = err
 			close(t.incoming)
@@ -154,89 +201,243 @@ func (t *handshakeTransport) readLoop() {
 		t.incoming <- p
 	}

-	// If we can't read, declare the writing part dead too.
-	t.mu.Lock()
-	defer t.mu.Unlock()
-	if t.writeError == nil {
-		t.writeError = t.readError
-	}
-	t.cond.Broadcast()
+	// Stop writers too.
+	t.recordWriteError(t.readError)
+
+	// Unblock the writer should it wait for this.
+	close(t.startKex)
+
+	// Don't close t.requestKex; it's also written to from writePacket.
 }

-func (t *handshakeTransport) readOnePacket() ([]byte, error) {
-	if t.readSinceKex > t.config.RekeyThreshold {
-		if err := t.requestKeyChange(); err != nil {
-			return nil, err
+func (t *handshakeTransport) pushPacket(p []byte) error {
+	if debugHandshake {
+		t.printPacket(p, true)
+	}
+	return t.conn.writePacket(p)
+}
+
+func (t *handshakeTransport) getWriteError() error {
+	t.mu.Lock()
+	defer t.mu.Unlock()
+	return t.writeError
+}
+
+func (t *handshakeTransport) recordWriteError(err error) {
+	t.mu.Lock()
+	defer t.mu.Unlock()
+	if t.writeError == nil && err != nil {
+		t.writeError = err
+	}
+}
+
+func (t *handshakeTransport) requestKeyExchange() {
+	select {
+	case t.requestKex <- struct{}{}:
+	default:
+		// something already requested a kex, so do nothing.
+	}
+}
+
+func (t *handshakeTransport) resetWriteThresholds() {
+	t.writePacketsLeft = packetRekeyThreshold
+	if t.config.RekeyThreshold > 0 {
+		t.writeBytesLeft = int64(t.config.RekeyThreshold)
+	} else if t.algorithms != nil {
+		t.writeBytesLeft = t.algorithms.w.rekeyBytes()
+	} else {
+		t.writeBytesLeft = 1 << 30
+	}
+}
+
+func (t *handshakeTransport) kexLoop() {
+
+write:
+	for t.getWriteError() == nil {
+		var request *pendingKex
+		var sent bool
+
+		for request == nil || !sent {
+			var ok bool
+			select {
+			case request, ok = <-t.startKex:
+				if !ok {
+					break write
+				}
+			case <-t.requestKex:
+				break
+			}
+
+			if !sent {
+				if err := t.sendKexInit(); err != nil {
+					t.recordWriteError(err)
+					break
+				}
+				sent = true
+			}
 		}
+
+		if err := t.getWriteError(); err != nil {
+			if request != nil {
+				request.done <- err
+			}
+			break
+		}
+
+		// We're not servicing t.requestKex, but that is OK:
+		// we never block on sending to t.requestKex.
+
+		// We're not servicing t.startKex, but the remote end
+		// has just sent us a kexInitMsg, so it can't send
+		// another key change request, until we close the done
+		// channel on the pendingKex request.
+
+		err := t.enterKeyExchange(request.otherInit)
+
+		t.mu.Lock()
+		t.writeError = err
+		t.sentInitPacket = nil
+		t.sentInitMsg = nil
+
+		t.resetWriteThresholds()
+
+		// we have completed the key exchange. Since the
+		// reader is still blocked, it is safe to clear out
+		// the requestKex channel. This avoids the situation
+		// where: 1) we consumed our own request for the
+		// initial kex, and 2) the kex from the remote side
+		// caused another send on the requestKex channel,
+	clear:
+		for {
+			select {
+			case <-t.requestKex:
+				//
+			default:
+				break clear
+			}
+		}
+
+		request.done <- t.writeError
+
+		// kex finished. Push packets that we received while
+		// the kex was in progress. Don't look at t.startKex
+		// and don't increment writtenSinceKex: if we trigger
+		// another kex while we are still busy with the last
+		// one, things will become very confusing.
+		for _, p := range t.pendingPackets {
+			t.writeError = t.pushPacket(p)
+			if t.writeError != nil {
+				break
+			}
+		}
+		t.pendingPackets = t.pendingPackets[:0]
+		t.mu.Unlock()
 	}

+	// drain startKex channel. We don't service t.requestKex
+	// because nobody does blocking sends there.
+	go func() {
+		for init := range t.startKex {
+			init.done <- t.writeError
+		}
+	}()
+
+	// Unblock reader.
+	t.conn.Close()
+}
+
+// The protocol uses uint32 for packet counters, so we can't let them
+// reach 1<<32.  We will actually read and write more packets than
+// this, though: the other side may send more packets, and after we
+// hit this limit on writing we will send a few more packets for the
+// key exchange itself.
+const packetRekeyThreshold = (1 << 31)
+
+func (t *handshakeTransport) resetReadThresholds() {
+	t.readPacketsLeft = packetRekeyThreshold
+	if t.config.RekeyThreshold > 0 {
+		t.readBytesLeft = int64(t.config.RekeyThreshold)
+	} else if t.algorithms != nil {
+		t.readBytesLeft = t.algorithms.r.rekeyBytes()
+	} else {
+		t.readBytesLeft = 1 << 30
+	}
+}
+
+func (t *handshakeTransport) readOnePacket(first bool) ([]byte, error) {
 	p, err := t.conn.readPacket()
 	if err != nil {
 		return nil, err
 	}

-	t.readSinceKex += uint64(len(p))
-	if debugHandshake {
-		msg, err := decode(p)
-		log.Printf("%s got %T %v (%v)", t.id(), msg, msg, err)
+	if t.readPacketsLeft > 0 {
+		t.readPacketsLeft--
+	} else {
+		t.requestKeyExchange()
 	}
+
+	if t.readBytesLeft > 0 {
+		t.readBytesLeft -= int64(len(p))
+	} else {
+		t.requestKeyExchange()
+	}
+
+	if debugHandshake {
+		t.printPacket(p, false)
+	}
+
+	if first && p[0] != msgKexInit {
+		return nil, fmt.Errorf("ssh: first packet should be msgKexInit")
+	}
+
 	if p[0] != msgKexInit {
 		return p, nil
 	}
-	err = t.enterKeyExchange(p)

-	t.mu.Lock()
-	if err != nil {
-		// drop connection
-		t.conn.Close()
-		t.writeError = err
+	firstKex := t.sessionID == nil
+
+	kex := pendingKex{
+		done:      make(chan error, 1),
+		otherInit: p,
 	}
+	t.startKex <- &kex
+	err = <-kex.done

 	if debugHandshake {
-		log.Printf("%s exited key exchange, err %v", t.id(), err)
+		log.Printf("%s exited key exchange (first %v), err %v", t.id(), firstKex, err)
 	}

-	// Unblock writers.
-	t.sentInitMsg = nil
-	t.sentInitPacket = nil
-	t.cond.Broadcast()
-	t.writtenSinceKex = 0
-	t.mu.Unlock()
-
 	if err != nil {
 		return nil, err
 	}

-	t.readSinceKex = 0
-	return []byte{msgNewKeys}, nil
+	t.resetReadThresholds()
+
+	// By default, a key exchange is hidden from higher layers by
+	// translating it into msgIgnore.
+	successPacket := []byte{msgIgnore}
+	if firstKex {
+		// sendKexInit() for the first kex waits for
+		// msgNewKeys so the authentication process is
+		// guaranteed to happen over an encrypted transport.
+		successPacket = []byte{msgNewKeys}
+	}
+
+	return successPacket, nil
 }

-// sendKexInit sends a key change message, and returns the message
-// that was sent. After initiating the key change, all writes will be
-// blocked until the change is done, and a failed key change will
-// close the underlying transport. This function is safe for
-// concurrent use by multiple goroutines.
-func (t *handshakeTransport) sendKexInit() (*kexInitMsg, []byte, error) {
+// sendKexInit sends a key change message.
+func (t *handshakeTransport) sendKexInit() error {
 	t.mu.Lock()
 	defer t.mu.Unlock()
-	return t.sendKexInitLocked()
-}
-
-func (t *handshakeTransport) requestKeyChange() error {
-	_, _, err := t.sendKexInit()
-	return err
-}
-
-// sendKexInitLocked sends a key change message. t.mu must be locked
-// while this happens.
-func (t *handshakeTransport) sendKexInitLocked() (*kexInitMsg, []byte, error) {
-	// kexInits may be sent either in response to the other side,
-	// or because our side wants to initiate a key change, so we
-	// may have already sent a kexInit. In that case, don't send a
-	// second kexInit.
 	if t.sentInitMsg != nil {
-		return t.sentInitMsg, t.sentInitPacket, nil
+		// kexInits may be sent either in response to the other side,
+		// or because our side wants to initiate a key change, so we
+		// may have already sent a kexInit. In that case, don't send a
+		// second kexInit.
+		return nil
 	}
+
 	msg := &kexInitMsg{
 		KexAlgos:                t.config.KeyExchanges,
 		CiphersClientServer:     t.config.Ciphers,
@@ -262,53 +463,65 @@ func (t *handshakeTransport) sendKexInitLocked() (*kexInitMsg, []byte, error) {
 	packetCopy := make([]byte, len(packet))
 	copy(packetCopy, packet)

-	if err := t.conn.writePacket(packetCopy); err != nil {
-		return nil, nil, err
+	if err := t.pushPacket(packetCopy); err != nil {
+		return err
 	}

 	t.sentInitMsg = msg
 	t.sentInitPacket = packet
-	return msg, packet, nil
+
+	return nil
 }

 func (t *handshakeTransport) writePacket(p []byte) error {
-	t.mu.Lock()
-	defer t.mu.Unlock()
-
-	if t.writtenSinceKex > t.config.RekeyThreshold {
-		t.sendKexInitLocked()
-	}
-	for t.sentInitMsg != nil && t.writeError == nil {
-		t.cond.Wait()
-	}
-	if t.writeError != nil {
-		return t.writeError
-	}
-	t.writtenSinceKex += uint64(len(p))
-
 	switch p[0] {
 	case msgKexInit:
 		return errors.New("ssh: only handshakeTransport can send kexInit")
 	case msgNewKeys:
 		return errors.New("ssh: only handshakeTransport can send newKeys")
-	default:
-		return t.conn.writePacket(p)
 	}
+
+	t.mu.Lock()
+	defer t.mu.Unlock()
+	if t.writeError != nil {
+		return t.writeError
+	}
+
+	if t.sentInitMsg != nil {
+		// Copy the packet so the writer can reuse the buffer.
+		cp := make([]byte, len(p))
+		copy(cp, p)
+		t.pendingPackets = append(t.pendingPackets, cp)
+		return nil
+	}
+
+	if t.writeBytesLeft > 0 {
+		t.writeBytesLeft -= int64(len(p))
+	} else {
+		t.requestKeyExchange()
+	}
+
+	if t.writePacketsLeft > 0 {
+		t.writePacketsLeft--
+	} else {
+		t.requestKeyExchange()
+	}
+
+	if err := t.pushPacket(p); err != nil {
+		t.writeError = err
+	}
+
+	return nil
 }

 func (t *handshakeTransport) Close() error {
 	return t.conn.Close()
 }

-// enterKeyExchange runs the key exchange.
 func (t *handshakeTransport) enterKeyExchange(otherInitPacket []byte) error {
 	if debugHandshake {
 		log.Printf("%s entered key exchange", t.id())
 	}
-	myInit, myInitPacket, err := t.sendKexInit()
-	if err != nil {
-		return err
-	}

 	otherInit := &kexInitMsg{}
 	if err := Unmarshal(otherInitPacket, otherInit); err != nil {
@@ -319,26 +532,35 @@ func (t *handshakeTransport) enterKeyExchange(otherInitPacket []byte) error {
 		clientVersion: t.clientVersion,
 		serverVersion: t.serverVersion,
 		clientKexInit: otherInitPacket,
-		serverKexInit: myInitPacket,
+		serverKexInit: t.sentInitPacket,
 	}

 	clientInit := otherInit
-	serverInit := myInit
+	serverInit := t.sentInitMsg
 	if len(t.hostKeys) == 0 {
-		clientInit = myInit
-		serverInit = otherInit
+		clientInit, serverInit = serverInit, clientInit

-		magics.clientKexInit = myInitPacket
+		magics.clientKexInit = t.sentInitPacket
 		magics.serverKexInit = otherInitPacket
 	}

-	algs, err := findAgreedAlgorithms(clientInit, serverInit)
+	var err error
+	t.algorithms, err = findAgreedAlgorithms(clientInit, serverInit)
 	if err != nil {
 		return err
 	}

 	// We don't send FirstKexFollows, but we handle receiving it.
-	if otherInit.FirstKexFollows && algs.kex != otherInit.KexAlgos[0] {
+	//
+	// RFC 4253 section 7 defines the kex and the agreement method for
+	// first_kex_packet_follows. It states that the guessed packet
+	// should be ignored if the "kex algorithm and/or the host
+	// key algorithm is guessed wrong (server and client have
+	// different preferred algorithm), or if any of the other
+	// algorithms cannot be agreed upon". The other algorithms have
+	// already been checked above so the kex algorithm and host key
+	// algorithm are checked here.
+	if otherInit.FirstKexFollows && (clientInit.KexAlgos[0] != serverInit.KexAlgos[0] || clientInit.ServerHostKeyAlgos[0] != serverInit.ServerHostKeyAlgos[0]) {
 		// other side sent a kex message for the wrong algorithm,
 		// which we have to ignore.
 		if _, err := t.conn.readPacket(); err != nil {
@@ -346,23 +568,30 @@ func (t *handshakeTransport) enterKeyExchange(otherInitPacket []byte) error {
 		}
 	}

-	kex, ok := kexAlgoMap[algs.kex]
+	kex, ok := kexAlgoMap[t.algorithms.kex]
 	if !ok {
-		return fmt.Errorf("ssh: unexpected key exchange algorithm %v", algs.kex)
+		return fmt.Errorf("ssh: unexpected key exchange algorithm %v", t.algorithms.kex)
 	}

 	var result *kexResult
 	if len(t.hostKeys) > 0 {
-		result, err = t.server(kex, algs, &magics)
+		result, err = t.server(kex, t.algorithms, &magics)
 	} else {
-		result, err = t.client(kex, algs, &magics)
+		result, err = t.client(kex, t.algorithms, &magics)
 	}

 	if err != nil {
 		return err
 	}

-	t.conn.prepareKeyChange(algs, result)
+	if t.sessionID == nil {
+		t.sessionID = result.H
+	}
+	result.SessionID = t.sessionID
+
+	if err := t.conn.prepareKeyChange(t.algorithms, result); err != nil {
+		return err
+	}
 	if err = t.conn.writePacket([]byte{msgNewKeys}); err != nil {
 		return err
 	}
@@ -371,6 +600,7 @@ func (t *handshakeTransport) enterKeyExchange(otherInitPacket []byte) error {
 	} else if packet[0] != msgNewKeys {
 		return unexpectedMessageError(msgNewKeys, packet[0])
 	}
+
 	return nil
 }

@@ -401,11 +631,9 @@ func (t *handshakeTransport) client(kex kexAlgorithm, algs *algorithms, magics *
 		return nil, err
 	}

-	if t.hostKeyCallback != nil {
-		err = t.hostKeyCallback(t.dialAddress, t.remoteAddr, hostKey)
-		if err != nil {
-			return nil, err
-		}
+	err = t.hostKeyCallback(t.dialAddress, t.remoteAddr, hostKey)
+	if err != nil {
+		return nil, err
 	}

 	return result, nil
@@ -8,8 +8,8 @@ import (
 	"crypto"
 	"crypto/ecdsa"
 	"crypto/elliptic"
-	"crypto/subtle"
 	"crypto/rand"
+	"crypto/subtle"
 	"errors"
 	"io"
 	"math/big"
@@ -46,7 +46,7 @@ type kexResult struct {
 	Hash crypto.Hash

 	// The session ID, which is the first H computed. This is used
-	// to signal data inside transport.
+	// to derive key material inside the transport.
 	SessionID []byte
 }

@@ -77,11 +77,11 @@ type kexAlgorithm interface {

 // dhGroup is a multiplicative group suitable for implementing Diffie-Hellman key agreement.
 type dhGroup struct {
-	g, p *big.Int
+	g, p, pMinus1 *big.Int
 }

 func (group *dhGroup) diffieHellman(theirPublic, myPrivate *big.Int) (*big.Int, error) {
-	if theirPublic.Sign() <= 0 || theirPublic.Cmp(group.p) >= 0 {
+	if theirPublic.Cmp(bigOne) <= 0 || theirPublic.Cmp(group.pMinus1) >= 0 {
 		return nil, errors.New("ssh: DH parameter out of bounds")
 	}
 	return new(big.Int).Exp(theirPublic, myPrivate, group.p), nil
@@ -90,10 +90,17 @@ func (group *dhGroup) diffieHellman(theirPublic, myPrivate *big.Int) (*big.Int,
 func (group *dhGroup) Client(c packetConn, randSource io.Reader, magics *handshakeMagics) (*kexResult, error) {
 	hashFunc := crypto.SHA1

-	x, err := rand.Int(randSource, group.p)
-	if err != nil {
-		return nil, err
+	var x *big.Int
+	for {
+		var err error
+		if x, err = rand.Int(randSource, group.pMinus1); err != nil {
+			return nil, err
+		}
+		if x.Sign() > 0 {
+			break
+		}
 	}
+
 	X := new(big.Int).Exp(group.g, x, group.p)
 	kexDHInit := kexDHInitMsg{
 		X: X,
@@ -146,9 +153,14 @@ func (group *dhGroup) Server(c packetConn, randSource io.Reader, magics *handsha
 		return
 	}

-	y, err := rand.Int(randSource, group.p)
-	if err != nil {
-		return
+	var y *big.Int
+	for {
+		if y, err = rand.Int(randSource, group.pMinus1); err != nil {
+			return
+		}
+		if y.Sign() > 0 {
+			break
+		}
 	}

 	Y := new(big.Int).Exp(group.g, y, group.p)
@@ -371,8 +383,9 @@ func init() {
 	// 4253 and Oakley Group 2 in RFC 2409.
 	p, _ := new(big.Int).SetString("FFFFFFFFFFFFFFFFC90FDAA22168C234C4C6628B80DC1CD129024E088A67CC74020BBEA63B139B22514A08798E3404DDEF9519B3CD3A431B302B0A6DF25F14374FE1356D6D51C245E485B576625E7EC6F44C42E9A637ED6B0BFF5CB6F406B7EDEE386BFB5A899FA5AE9F24117C4B1FE649286651ECE65381FFFFFFFFFFFFFFFF", 16)
 	kexAlgoMap[kexAlgoDH1SHA1] = &dhGroup{
-		g: new(big.Int).SetInt64(2),
-		p: p,
+		g:       new(big.Int).SetInt64(2),
+		p:       p,
+		pMinus1: new(big.Int).Sub(p, bigOne),
 	}

 	// This is the group called diffie-hellman-group14-sha1 in RFC
@@ -380,8 +393,9 @@ func init() {
 	p, _ = new(big.Int).SetString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

 	kexAlgoMap[kexAlgoDH14SHA1] = &dhGroup{
-		g: new(big.Int).SetInt64(2),
-		p: p,
+		g:       new(big.Int).SetInt64(2),
+		p:       p,
+		pMinus1: new(big.Int).Sub(p, bigOne),
 	}

 	kexAlgoMap[kexAlgoECDH521] = &ecdh{elliptic.P521()}
@@ -10,15 +10,21 @@ import (
 	"crypto/dsa"
 	"crypto/ecdsa"
 	"crypto/elliptic"
+	"crypto/md5"
 	"crypto/rsa"
+	"crypto/sha256"
 	"crypto/x509"
 	"encoding/asn1"
 	"encoding/base64"
+	"encoding/hex"
 	"encoding/pem"
 	"errors"
 	"fmt"
 	"io"
 	"math/big"
+	"strings"
+
+	"golang.org/x/crypto/ed25519"
 )

 // These constants represent the algorithm names for key types supported by this
@@ -29,6 +35,7 @@ const (
 	KeyAlgoECDSA256 = "ecdsa-sha2-nistp256"
 	KeyAlgoECDSA384 = "ecdsa-sha2-nistp384"
 	KeyAlgoECDSA521 = "ecdsa-sha2-nistp521"
+	KeyAlgoED25519  = "ssh-ed25519"
 )

 // parsePubKey parses a public key of the given algorithm.
@@ -41,14 +48,16 @@ func parsePubKey(in []byte, algo string) (pubKey PublicKey, rest []byte, err err
 		return parseDSA(in)
 	case KeyAlgoECDSA256, KeyAlgoECDSA384, KeyAlgoECDSA521:
 		return parseECDSA(in)
-	case CertAlgoRSAv01, CertAlgoDSAv01, CertAlgoECDSA256v01, CertAlgoECDSA384v01, CertAlgoECDSA521v01:
+	case KeyAlgoED25519:
+		return parseED25519(in)
+	case CertAlgoRSAv01, CertAlgoDSAv01, CertAlgoECDSA256v01, CertAlgoECDSA384v01, CertAlgoECDSA521v01, CertAlgoED25519v01:
 		cert, err := parseCert(in, certToPrivAlgo(algo))
 		if err != nil {
 			return nil, nil, err
 		}
 		return cert, nil, nil
 	}
-	return nil, nil, fmt.Errorf("ssh: unknown key algorithm: %v", err)
+	return nil, nil, fmt.Errorf("ssh: unknown key algorithm: %v", algo)
 }

 // parseAuthorizedKey parses a public key in OpenSSH authorized_keys format
@@ -77,6 +86,79 @@ func parseAuthorizedKey(in []byte) (out PublicKey, comment string, err error) {
 	return out, comment, nil
 }

+// ParseKnownHosts parses an entry in the format of the known_hosts file.
+//
+// The known_hosts format is documented in the sshd(8) manual page. This
+// function will parse a single entry from in. On successful return, marker
+// will contain the optional marker value (i.e. "cert-authority" or "revoked")
+// or else be empty, hosts will contain the hosts that this entry matches,
+// pubKey will contain the public key and comment will contain any trailing
+// comment at the end of the line. See the sshd(8) manual page for the various
+// forms that a host string can take.
+//
+// The unparsed remainder of the input will be returned in rest. This function
+// can be called repeatedly to parse multiple entries.
+//
+// If no entries were found in the input then err will be io.EOF. Otherwise a
+// non-nil err value indicates a parse error.
+func ParseKnownHosts(in []byte) (marker string, hosts []string, pubKey PublicKey, comment string, rest []byte, err error) {
+	for len(in) > 0 {
+		end := bytes.IndexByte(in, '\n')
+		if end != -1 {
+			rest = in[end+1:]
+			in = in[:end]
+		} else {
+			rest = nil
+		}
+
+		end = bytes.IndexByte(in, '\r')
+		if end != -1 {
+			in = in[:end]
+		}
+
+		in = bytes.TrimSpace(in)
+		if len(in) == 0 || in[0] == '#' {
+			in = rest
+			continue
+		}
+
+		i := bytes.IndexAny(in, " \t")
+		if i == -1 {
+			in = rest
+			continue
+		}
+
+		// Strip out the beginning of the known_host key.
+		// This is either an optional marker or a (set of) hostname(s).
+		keyFields := bytes.Fields(in)
+		if len(keyFields) < 3 || len(keyFields) > 5 {
+			return "", nil, nil, "", nil, errors.New("ssh: invalid entry in known_hosts data")
+		}
+
+		// keyFields[0] is either "@cert-authority", "@revoked" or a comma separated
+		// list of hosts
+		marker := ""
+		if keyFields[0][0] == '@' {
+			marker = string(keyFields[0][1:])
+			keyFields = keyFields[1:]
+		}
+
+		hosts := string(keyFields[0])
+		// keyFields[1] contains the key type (e.g. “ssh-rsa”).
+		// However, that information is duplicated inside the
+		// base64-encoded key and so is ignored here.
+
+		key := bytes.Join(keyFields[2:], []byte(" "))
+		if pubKey, comment, err = parseAuthorizedKey(key); err != nil {
+			return "", nil, nil, "", nil, err
+		}
+
+		return marker, strings.Split(hosts, ","), pubKey, comment, rest, nil
+	}
+
+	return "", nil, nil, "", nil, io.EOF
+}
+
 // ParseAuthorizedKeys parses a public key from an authorized_keys
 // file used in OpenSSH according to the sshd(8) manual page.
 func ParseAuthorizedKey(in []byte) (out PublicKey, comment string, options []string, rest []byte, err error) {
@@ -202,6 +284,12 @@ type PublicKey interface {
 	Verify(data []byte, sig *Signature) error
 }

+// CryptoPublicKey, if implemented by a PublicKey,
+// returns the underlying crypto.PublicKey form of the key.
+type CryptoPublicKey interface {
+	CryptoPublicKey() crypto.PublicKey
+}
+
 // A Signer can create signatures that verify against a public key.
 type Signer interface {
 	// PublicKey returns an associated PublicKey instance.
@@ -245,6 +333,8 @@ func parseRSA(in []byte) (out PublicKey, rest []byte, err error) {

 func (r *rsaPublicKey) Marshal() []byte {
 	e := new(big.Int).SetInt64(int64(r.E))
+	// RSA publickey struct layout should match the struct used by
+	// parseRSACert in the x/crypto/ssh/agent package.
 	wirekey := struct {
 		Name string
 		E    *big.Int
@@ -267,6 +357,10 @@ func (r *rsaPublicKey) Verify(data []byte, sig *Signature) error {
 	return rsa.VerifyPKCS1v15((*rsa.PublicKey)(r), crypto.SHA1, digest, sig.Blob)
 }

+func (r *rsaPublicKey) CryptoPublicKey() crypto.PublicKey {
+	return (*rsa.PublicKey)(r)
+}
+
 type dsaPublicKey dsa.PublicKey

 func (r *dsaPublicKey) Type() string {
@@ -295,6 +389,8 @@ func parseDSA(in []byte) (out PublicKey, rest []byte, err error) {
 }

 func (k *dsaPublicKey) Marshal() []byte {
+	// DSA publickey struct layout should match the struct used by
+	// parseDSACert in the x/crypto/ssh/agent package.
 	w := struct {
 		Name       string
 		P, Q, G, Y *big.Int
@@ -333,6 +429,10 @@ func (k *dsaPublicKey) Verify(data []byte, sig *Signature) error {
 	return errors.New("ssh: signature did not verify")
 }

+func (k *dsaPublicKey) CryptoPublicKey() crypto.PublicKey {
+	return (*dsa.PublicKey)(k)
+}
+
 type dsaPrivateKey struct {
 	*dsa.PrivateKey
 }
@@ -381,6 +481,55 @@ func (key *ecdsaPublicKey) nistID() string {
 	panic("ssh: unsupported ecdsa key size")
 }

+type ed25519PublicKey ed25519.PublicKey
+
+func (key ed25519PublicKey) Type() string {
+	return KeyAlgoED25519
+}
+
+func parseED25519(in []byte) (out PublicKey, rest []byte, err error) {
+	var w struct {
+		KeyBytes []byte
+		Rest     []byte `ssh:"rest"`
+	}
+
+	if err := Unmarshal(in, &w); err != nil {
+		return nil, nil, err
+	}
+
+	key := ed25519.PublicKey(w.KeyBytes)
+
+	return (ed25519PublicKey)(key), w.Rest, nil
+}
+
+func (key ed25519PublicKey) Marshal() []byte {
+	w := struct {
+		Name     string
+		KeyBytes []byte
+	}{
+		KeyAlgoED25519,
+		[]byte(key),
+	}
+	return Marshal(&w)
+}
+
+func (key ed25519PublicKey) Verify(b []byte, sig *Signature) error {
+	if sig.Format != key.Type() {
+		return fmt.Errorf("ssh: signature type %s for key type %s", sig.Format, key.Type())
+	}
+
+	edKey := (ed25519.PublicKey)(key)
+	if ok := ed25519.Verify(edKey, b, sig.Blob); !ok {
+		return errors.New("ssh: signature did not verify")
+	}
+
+	return nil
+}
+
+func (k ed25519PublicKey) CryptoPublicKey() crypto.PublicKey {
+	return ed25519.PublicKey(k)
+}
+
 func supportedEllipticCurve(curve elliptic.Curve) bool {
 	return curve == elliptic.P256() || curve == elliptic.P384() || curve == elliptic.P521()
 }
@@ -433,6 +582,8 @@ func parseECDSA(in []byte) (out PublicKey, rest []byte, err error) {
 func (key *ecdsaPublicKey) Marshal() []byte {
 	// See RFC 5656, section 3.1.
 	keyBytes := elliptic.Marshal(key.Curve, key.X, key.Y)
+	// ECDSA publickey struct layout should match the struct used by
+	// parseECDSACert in the x/crypto/ssh/agent package.
 	w := struct {
 		Name string
 		ID   string
@@ -474,6 +625,10 @@ func (key *ecdsaPublicKey) Verify(data []byte, sig *Signature) error {
 	return errors.New("ssh: signature did not verify")
 }

+func (k *ecdsaPublicKey) CryptoPublicKey() crypto.PublicKey {
+	return (*ecdsa.PublicKey)(k)
+}
+
 // NewSignerFromKey takes an *rsa.PrivateKey, *dsa.PrivateKey,
 // *ecdsa.PrivateKey or any other crypto.Signer and returns a corresponding
 // Signer instance. ECDSA keys must use P-256, P-384 or P-521.
@@ -517,13 +672,19 @@ func (s *wrappedSigner) Sign(rand io.Reader, data []byte) (*Signature, error) {
 		hashFunc = crypto.SHA1
 	case *ecdsaPublicKey:
 		hashFunc = ecHash(key.Curve)
+	case ed25519PublicKey:
 	default:
 		return nil, fmt.Errorf("ssh: unsupported key type %T", key)
 	}

-	h := hashFunc.New()
-	h.Write(data)
-	digest := h.Sum(nil)
+	var digest []byte
+	if hashFunc != 0 {
+		h := hashFunc.New()
+		h.Write(data)
+		digest = h.Sum(nil)
+	} else {
+		digest = data
+	}

 	signature, err := s.signer.Sign(rand, digest, hashFunc)
 	if err != nil {
@@ -563,9 +724,9 @@ func (s *wrappedSigner) Sign(rand io.Reader, data []byte) (*Signature, error) {
 	}, nil
 }

-// NewPublicKey takes an *rsa.PublicKey, *dsa.PublicKey, *ecdsa.PublicKey or
-// any other crypto.Signer and returns a corresponding Signer instance. ECDSA
-// keys must use P-256, P-384 or P-521.
+// NewPublicKey takes an *rsa.PublicKey, *dsa.PublicKey, *ecdsa.PublicKey,
+// or ed25519.PublicKey returns a corresponding PublicKey instance.
+// ECDSA keys must use P-256, P-384 or P-521.
 func NewPublicKey(key interface{}) (PublicKey, error) {
 	switch key := key.(type) {
 	case *rsa.PublicKey:
@@ -577,6 +738,8 @@ func NewPublicKey(key interface{}) (PublicKey, error) {
 		return (*ecdsaPublicKey)(key), nil
 	case *dsa.PublicKey:
 		return (*dsaPublicKey)(key), nil
+	case ed25519.PublicKey:
+		return (ed25519PublicKey)(key), nil
 	default:
 		return nil, fmt.Errorf("ssh: unsupported key type %T", key)
 	}
@@ -593,6 +756,26 @@ func ParsePrivateKey(pemBytes []byte) (Signer, error) {
 	return NewSignerFromKey(key)
 }

+// ParsePrivateKeyWithPassphrase returns a Signer from a PEM encoded private
+// key and passphrase. It supports the same keys as
+// ParseRawPrivateKeyWithPassphrase.
+func ParsePrivateKeyWithPassphrase(pemBytes, passPhrase []byte) (Signer, error) {
+	key, err := ParseRawPrivateKeyWithPassphrase(pemBytes, passPhrase)
+	if err != nil {
+		return nil, err
+	}
+
+	return NewSignerFromKey(key)
+}
+
+// encryptedBlock tells whether a private key is
+// encrypted by examining its Proc-Type header
+// for a mention of ENCRYPTED
+// according to RFC 1421 Section 4.6.1.1.
+func encryptedBlock(block *pem.Block) bool {
+	return strings.Contains(block.Headers["Proc-Type"], "ENCRYPTED")
+}
+
 // ParseRawPrivateKey returns a private key from a PEM encoded private key. It
 // supports RSA (PKCS#1), DSA (OpenSSL), and ECDSA private keys.
 func ParseRawPrivateKey(pemBytes []byte) (interface{}, error) {
@@ -601,6 +784,10 @@ func ParseRawPrivateKey(pemBytes []byte) (interface{}, error) {
 		return nil, errors.New("ssh: no key found")
 	}

+	if encryptedBlock(block) {
+		return nil, errors.New("ssh: cannot decode encrypted private keys")
+	}
+
 	switch block.Type {
 	case "RSA PRIVATE KEY":
 		return x509.ParsePKCS1PrivateKey(block.Bytes)
@@ -608,6 +795,45 @@ func ParseRawPrivateKey(pemBytes []byte) (interface{}, error) {
 		return x509.ParseECPrivateKey(block.Bytes)
 	case "DSA PRIVATE KEY":
 		return ParseDSAPrivateKey(block.Bytes)
+	case "OPENSSH PRIVATE KEY":
+		return parseOpenSSHPrivateKey(block.Bytes)
+	default:
+		return nil, fmt.Errorf("ssh: unsupported key type %q", block.Type)
+	}
+}
+
+// ParseRawPrivateKeyWithPassphrase returns a private key decrypted with
+// passphrase from a PEM encoded private key. If wrong passphrase, return
+// x509.IncorrectPasswordError.
+func ParseRawPrivateKeyWithPassphrase(pemBytes, passPhrase []byte) (interface{}, error) {
+	block, _ := pem.Decode(pemBytes)
+	if block == nil {
+		return nil, errors.New("ssh: no key found")
+	}
+	buf := block.Bytes
+
+	if encryptedBlock(block) {
+		if x509.IsEncryptedPEMBlock(block) {
+			var err error
+			buf, err = x509.DecryptPEMBlock(block, passPhrase)
+			if err != nil {
+				if err == x509.IncorrectPasswordError {
+					return nil, err
+				}
+				return nil, fmt.Errorf("ssh: cannot decode encrypted private keys: %v", err)
+			}
+		}
+	}
+
+	switch block.Type {
+	case "RSA PRIVATE KEY":
+		return x509.ParsePKCS1PrivateKey(buf)
+	case "EC PRIVATE KEY":
+		return x509.ParseECPrivateKey(buf)
+	case "DSA PRIVATE KEY":
+		return ParseDSAPrivateKey(buf)
+	case "OPENSSH PRIVATE KEY":
+		return parseOpenSSHPrivateKey(buf)
 	default:
 		return nil, fmt.Errorf("ssh: unsupported key type %q", block.Type)
 	}
@@ -621,8 +847,8 @@ func ParseDSAPrivateKey(der []byte) (*dsa.PrivateKey, error) {
 		P       *big.Int
 		Q       *big.Int
 		G       *big.Int
-		Priv    *big.Int
 		Pub     *big.Int
+		Priv    *big.Int
 	}
 	rest, err := asn1.Unmarshal(der, &k)
 	if err != nil {
@@ -639,8 +865,142 @@ func ParseDSAPrivateKey(der []byte) (*dsa.PrivateKey, error) {
 				Q: k.Q,
 				G: k.G,
 			},
-			Y: k.Priv,
+			Y: k.Pub,
 		},
-		X: k.Pub,
+		X: k.Priv,
 	}, nil
 }
+
+// Implemented based on the documentation at
+// https://github.com/openssh/openssh-portable/blob/master/PROTOCOL.key
+func parseOpenSSHPrivateKey(key []byte) (crypto.PrivateKey, error) {
+	magic := append([]byte("openssh-key-v1"), 0)
+	if !bytes.Equal(magic, key[0:len(magic)]) {
+		return nil, errors.New("ssh: invalid openssh private key format")
+	}
+	remaining := key[len(magic):]
+
+	var w struct {
+		CipherName   string
+		KdfName      string
+		KdfOpts      string
+		NumKeys      uint32
+		PubKey       []byte
+		PrivKeyBlock []byte
+	}
+
+	if err := Unmarshal(remaining, &w); err != nil {
+		return nil, err
+	}
+
+	if w.KdfName != "none" || w.CipherName != "none" {
+		return nil, errors.New("ssh: cannot decode encrypted private keys")
+	}
+
+	pk1 := struct {
+		Check1  uint32
+		Check2  uint32
+		Keytype string
+		Rest    []byte `ssh:"rest"`
+	}{}
+
+	if err := Unmarshal(w.PrivKeyBlock, &pk1); err != nil {
+		return nil, err
+	}
+
+	if pk1.Check1 != pk1.Check2 {
+		return nil, errors.New("ssh: checkint mismatch")
+	}
+
+	// we only handle ed25519 and rsa keys currently
+	switch pk1.Keytype {
+	case KeyAlgoRSA:
+		// https://github.com/openssh/openssh-portable/blob/master/sshkey.c#L2760-L2773
+		key := struct {
+			N       *big.Int
+			E       *big.Int
+			D       *big.Int
+			Iqmp    *big.Int
+			P       *big.Int
+			Q       *big.Int
+			Comment string
+			Pad     []byte `ssh:"rest"`
+		}{}
+
+		if err := Unmarshal(pk1.Rest, &key); err != nil {
+			return nil, err
+		}
+
+		for i, b := range key.Pad {
+			if int(b) != i+1 {
+				return nil, errors.New("ssh: padding not as expected")
+			}
+		}
+
+		pk := &rsa.PrivateKey{
+			PublicKey: rsa.PublicKey{
+				N: key.N,
+				E: int(key.E.Int64()),
+			},
+			D:      key.D,
+			Primes: []*big.Int{key.P, key.Q},
+		}
+
+		if err := pk.Validate(); err != nil {
+			return nil, err
+		}
+
+		pk.Precompute()
+
+		return pk, nil
+	case KeyAlgoED25519:
+		key := struct {
+			Pub     []byte
+			Priv    []byte
+			Comment string
+			Pad     []byte `ssh:"rest"`
+		}{}
+
+		if err := Unmarshal(pk1.Rest, &key); err != nil {
+			return nil, err
+		}
+
+		if len(key.Priv) != ed25519.PrivateKeySize {
+			return nil, errors.New("ssh: private key unexpected length")
+		}
+
+		for i, b := range key.Pad {
+			if int(b) != i+1 {
+				return nil, errors.New("ssh: padding not as expected")
+			}
+		}
+
+		pk := ed25519.PrivateKey(make([]byte, ed25519.PrivateKeySize))
+		copy(pk, key.Priv)
+		return &pk, nil
+	default:
+		return nil, errors.New("ssh: unhandled key type")
+	}
+}
+
+// FingerprintLegacyMD5 returns the user presentation of the key's
+// fingerprint as described by RFC 4716 section 4.
+func FingerprintLegacyMD5(pubKey PublicKey) string {
+	md5sum := md5.Sum(pubKey.Marshal())
+	hexarray := make([]string, len(md5sum))
+	for i, c := range md5sum {
+		hexarray[i] = hex.EncodeToString([]byte{c})
+	}
+	return strings.Join(hexarray, ":")
+}
+
+// FingerprintSHA256 returns the user presentation of the key's
+// fingerprint as unpadded base64 encoded sha256 hash.
+// This format was introduced from OpenSSH 6.8.
+// https://www.openssh.com/txt/release-6.8
+// https://tools.ietf.org/html/rfc4648#section-3.2 (unpadded base64 encoding)
+func FingerprintSHA256(pubKey PublicKey) string {
+	sha256sum := sha256.Sum256(pubKey.Marshal())
+	hash := base64.RawStdEncoding.EncodeToString(sha256sum[:])
+	return "SHA256:" + hash
+}
@@ -15,6 +15,7 @@ import (

 type macMode struct {
 	keySize int
+	etm     bool
 	new     func(key []byte) hash.Hash
 }

@@ -45,13 +46,16 @@ func (t truncatingMAC) Size() int {
 func (t truncatingMAC) BlockSize() int { return t.hmac.BlockSize() }

 var macModes = map[string]*macMode{
-	"hmac-sha2-256": {32, func(key []byte) hash.Hash {
+	"hmac-sha2-256-etm@openssh.com": {32, true, func(key []byte) hash.Hash {
 		return hmac.New(sha256.New, key)
 	}},
-	"hmac-sha1": {20, func(key []byte) hash.Hash {
+	"hmac-sha2-256": {32, false, func(key []byte) hash.Hash {
+		return hmac.New(sha256.New, key)
+	}},
+	"hmac-sha1": {20, false, func(key []byte) hash.Hash {
 		return hmac.New(sha1.New, key)
 	}},
-	"hmac-sha1-96": {20, func(key []byte) hash.Hash {
+	"hmac-sha1-96": {20, false, func(key []byte) hash.Hash {
 		return truncatingMAC{12, hmac.New(sha1.New, key)}
 	}},
 }
@@ -13,6 +13,7 @@ import (
 	"math/big"
 	"reflect"
 	"strconv"
+	"strings"
 )

 // These are SSH message type numbers. They are scattered around several
@@ -47,7 +48,7 @@ type disconnectMsg struct {
 }

 func (d *disconnectMsg) Error() string {
-	return fmt.Sprintf("ssh: disconnect reason %d: %s", d.Reason, d.Message)
+	return fmt.Sprintf("ssh: disconnect, reason %d: %s", d.Reason, d.Message)
 }

 // See RFC 4253, section 7.1.
@@ -124,6 +125,10 @@ type userAuthRequestMsg struct {
 	Payload []byte `ssh:"rest"`
 }

+// Used for debug printouts of packets.
+type userAuthSuccessMsg struct {
+}
+
 // See RFC 4252, section 5.1
 const msgUserAuthFailure = 51

@@ -158,6 +163,13 @@ type channelOpenMsg struct {
 const msgChannelExtendedData = 95
 const msgChannelData = 94

+// Used for debug print outs of packets.
+type channelDataMsg struct {
+	PeersId uint32 `sshtype:"94"`
+	Length  uint32
+	Rest    []byte `ssh:"rest"`
+}
+
 // See RFC 4254, section 5.1.
 const msgChannelOpenConfirm = 91

@@ -255,17 +267,19 @@ type userAuthPubKeyOkMsg struct {
 	PubKey []byte
 }

-// typeTag returns the type byte for the given type. The type should
-// be struct.
-func typeTag(structType reflect.Type) byte {
-	var tag byte
-	var tagStr string
-	tagStr = structType.Field(0).Tag.Get("sshtype")
-	i, err := strconv.Atoi(tagStr)
-	if err == nil {
-		tag = byte(i)
+// typeTags returns the possible type bytes for the given reflect.Type, which
+// should be a struct. The possible values are separated by a '|' character.
+func typeTags(structType reflect.Type) (tags []byte) {
+	tagStr := structType.Field(0).Tag.Get("sshtype")
+
+	for _, tag := range strings.Split(tagStr, "|") {
+		i, err := strconv.Atoi(tag)
+		if err == nil {
+			tags = append(tags, byte(i))
+		}
 	}
-	return tag
+
+	return tags
 }

 func fieldError(t reflect.Type, field int, problem string) error {
@@ -279,19 +293,34 @@ var errShortRead = errors.New("ssh: short read")

 // Unmarshal parses data in SSH wire format into a structure. The out
 // argument should be a pointer to struct. If the first member of the
-// struct has the "sshtype" tag set to a number in decimal, the packet
-// must start that number.  In case of error, Unmarshal returns a
-// ParseError or UnexpectedMessageError.
+// struct has the "sshtype" tag set to a '|'-separated set of numbers
+// in decimal, the packet must start with one of those numbers. In
+// case of error, Unmarshal returns a ParseError or
+// UnexpectedMessageError.
 func Unmarshal(data []byte, out interface{}) error {
 	v := reflect.ValueOf(out).Elem()
 	structType := v.Type()
-	expectedType := typeTag(structType)
+	expectedTypes := typeTags(structType)
+
+	var expectedType byte
+	if len(expectedTypes) > 0 {
+		expectedType = expectedTypes[0]
+	}
+
 	if len(data) == 0 {
 		return parseError(expectedType)
 	}
-	if expectedType > 0 {
-		if data[0] != expectedType {
-			return unexpectedMessageError(expectedType, data[0])
+
+	if len(expectedTypes) > 0 {
+		goodType := false
+		for _, e := range expectedTypes {
+			if e > 0 && data[0] == e {
+				goodType = true
+				break
+			}
+		}
+		if !goodType {
+			return fmt.Errorf("ssh: unexpected message type %d (expected one of %v)", data[0], expectedTypes)
 		}
 		data = data[1:]
 	}
@@ -375,7 +404,7 @@ func Unmarshal(data []byte, out interface{}) error {
 				return fieldError(structType, i, "pointer to unsupported type")
 			}
 		default:
-			return fieldError(structType, i, "unsupported type")
+			return fieldError(structType, i, fmt.Sprintf("unsupported type: %v", t))
 		}
 	}

@@ -398,9 +427,9 @@ func Marshal(msg interface{}) []byte {

 func marshalStruct(out []byte, msg interface{}) []byte {
 	v := reflect.Indirect(reflect.ValueOf(msg))
-	msgType := typeTag(v.Type())
-	if msgType > 0 {
-		out = append(out, msgType)
+	msgTypes := typeTags(v.Type())
+	if len(msgTypes) > 0 {
+		out = append(out, msgTypes[0])
 	}

 	for i, n := 0, v.NumField(); i < n; i++ {
@@ -687,6 +716,8 @@ func decode(packet []byte) (interface{}, error) {
 		msg = new(kexDHReplyMsg)
 	case msgUserAuthRequest:
 		msg = new(userAuthRequestMsg)
+	case msgUserAuthSuccess:
+		return new(userAuthSuccessMsg), nil
 	case msgUserAuthFailure:
 		msg = new(userAuthFailureMsg)
 	case msgUserAuthPubKeyOk:
@@ -699,6 +730,8 @@ func decode(packet []byte) (interface{}, error) {
 		msg = new(globalRequestFailureMsg)
 	case msgChannelOpen:
 		msg = new(channelOpenMsg)
+	case msgChannelData:
+		msg = new(channelDataMsg)
 	case msgChannelOpenConfirm:
 		msg = new(channelOpenConfirmMsg)
 	case msgChannelOpenFailure:
@@ -116,9 +116,9 @@ func (m *mux) Wait() error {
 func newMux(p packetConn) *mux {
 	m := &mux{
 		conn:             p,
-		incomingChannels: make(chan NewChannel, 16),
+		incomingChannels: make(chan NewChannel, chanSize),
 		globalResponses:  make(chan interface{}, 1),
-		incomingRequests: make(chan *Request, 16),
+		incomingRequests: make(chan *Request, chanSize),
 		errCond:          newCond(),
 	}
 	if debugMux {
@@ -131,6 +131,9 @@ func newMux(p packetConn) *mux {

 func (m *mux) sendMessage(msg interface{}) error {
 	p := Marshal(msg)
+	if debugMux {
+		log.Printf("send global(%d): %#v", m.chanList.offset, msg)
+	}
 	return m.conn.writePacket(p)
 }

@@ -175,18 +178,6 @@ func (m *mux) ackRequest(ok bool, data []byte) error {
 	return m.sendMessage(globalRequestFailureMsg{Data: data})
 }

-// TODO(hanwen): Disconnect is a transport layer message. We should
-// probably send and receive Disconnect somewhere in the transport
-// code.
-
-// Disconnect sends a disconnect message.
-func (m *mux) Disconnect(reason uint32, message string) error {
-	return m.sendMessage(disconnectMsg{
-		Reason:  reason,
-		Message: message,
-	})
-}
-
 func (m *mux) Close() error {
 	return m.conn.Close()
 }
@@ -236,11 +227,6 @@ func (m *mux) onePacket() error {
 	}

 	switch packet[0] {
-	case msgNewKeys:
-		// Ignore notification of key change.
-		return nil
-	case msgDisconnect:
-		return m.handleDisconnect(packet)
 	case msgChannelOpen:
 		return m.handleChannelOpen(packet)
 	case msgGlobalRequest, msgRequestSuccess, msgRequestFailure:
@@ -260,18 +246,6 @@ func (m *mux) onePacket() error {
 	return ch.handlePacket(packet)
 }

-func (m *mux) handleDisconnect(packet []byte) error {
-	var d disconnectMsg
-	if err := Unmarshal(packet, &d); err != nil {
-		return err
-	}
-
-	if debugMux {
-		log.Printf("caught disconnect: %v", d)
-	}
-	return &d
-}
-
 func (m *mux) handleGlobalPacket(packet []byte) error {
 	msg, err := decode(packet)
 	if err != nil {
@@ -10,26 +10,38 @@ import (
 	"fmt"
 	"io"
 	"net"
+	"strings"
 )

 // The Permissions type holds fine-grained permissions that are
-// specific to a user or a specific authentication method for a
-// user. Permissions, except for "source-address", must be enforced in
-// the server application layer, after successful authentication. The
-// Permissions are passed on in ServerConn so a server implementation
-// can honor them.
+// specific to a user or a specific authentication method for a user.
+// The Permissions value for a successful authentication attempt is
+// available in ServerConn, so it can be used to pass information from
+// the user-authentication phase to the application layer.
 type Permissions struct {
-	// Critical options restrict default permissions. Common
-	// restrictions are "source-address" and "force-command". If
-	// the server cannot enforce the restriction, or does not
-	// recognize it, the user should not authenticate.
+	// CriticalOptions indicate restrictions to the default
+	// permissions, and are typically used in conjunction with
+	// user certificates. The standard for SSH certificates
+	// defines "force-command" (only allow the given command to
+	// execute) and "source-address" (only allow connections from
+	// the given address). The SSH package currently only enforces
+	// the "source-address" critical option. It is up to server
+	// implementations to enforce other critical options, such as
+	// "force-command", by checking them after the SSH handshake
+	// is successful. In general, SSH servers should reject
+	// connections that specify critical options that are unknown
+	// or not supported.
 	CriticalOptions map[string]string

 	// Extensions are extra functionality that the server may
-	// offer on authenticated connections. Common extensions are
-	// "permit-agent-forwarding", "permit-X11-forwarding". Lack of
-	// support for an extension does not preclude authenticating a
-	// user.
+	// offer on authenticated connections. Lack of support for an
+	// extension does not preclude authenticating a user. Common
+	// extensions are "permit-agent-forwarding",
+	// "permit-X11-forwarding". The Go SSH library currently does
+	// not act on any extension, and it is up to server
+	// implementations to honor them. Extensions can be used to
+	// pass data from the authentication callbacks to the server
+	// application layer.
 	Extensions map[string]string
 }

@@ -44,13 +56,24 @@ type ServerConfig struct {
 	// authenticating.
 	NoClientAuth bool

+	// MaxAuthTries specifies the maximum number of authentication attempts
+	// permitted per connection. If set to a negative number, the number of
+	// attempts are unlimited. If set to zero, the number of attempts are limited
+	// to 6.
+	MaxAuthTries int
+
 	// PasswordCallback, if non-nil, is called when a user
 	// attempts to authenticate using a password.
 	PasswordCallback func(conn ConnMetadata, password []byte) (*Permissions, error)

-	// PublicKeyCallback, if non-nil, is called when a client attempts public
-	// key authentication. It must return true if the given public key is
-	// valid for the given user. For example, see CertChecker.Authenticate.
+	// PublicKeyCallback, if non-nil, is called when a client
+	// offers a public key for authentication. It must return true
+	// if the given public key can be used to authenticate the
+	// given user. For example, see CertChecker.Authenticate. A
+	// call to this function does not guarantee that the key
+	// offered is in fact used to authenticate. To record any data
+	// depending on the public key, store it inside a
+	// Permissions.Extensions entry.
 	PublicKeyCallback func(conn ConnMetadata, key PublicKey) (*Permissions, error)

 	// KeyboardInteractiveCallback, if non-nil, is called when
@@ -142,6 +165,10 @@ type ServerConn struct {
 func NewServerConn(c net.Conn, config *ServerConfig) (*ServerConn, <-chan NewChannel, <-chan *Request, error) {
 	fullConf := *config
 	fullConf.SetDefaults()
+	if fullConf.MaxAuthTries == 0 {
+		fullConf.MaxAuthTries = 6
+	}
+
 	s := &connection{
 		sshConn: sshConn{conn: c},
 	}
@@ -188,16 +215,10 @@ func (s *connection) serverHandshake(config *ServerConfig) (*Permissions, error)
 	tr := newTransport(s.sshConn.conn, config.Rand, false /* not client */)
 	s.transport = newServerTransport(tr, s.clientVersion, s.serverVersion, config)

-	if err := s.transport.requestKeyChange(); err != nil {
+	if err := s.transport.waitSession(); err != nil {
 		return nil, err
 	}

-	if packet, err := s.transport.readPacket(); err != nil {
-		return nil, err
-	} else if packet[0] != msgNewKeys {
-		return nil, unexpectedMessageError(msgNewKeys, packet[0])
-	}
-
 	// We just did the key change, so the session ID is established.
 	s.sessionID = s.transport.getSessionID()

@@ -230,14 +251,14 @@ func (s *connection) serverHandshake(config *ServerConfig) (*Permissions, error)

 func isAcceptableAlgo(algo string) bool {
 	switch algo {
-	case KeyAlgoRSA, KeyAlgoDSA, KeyAlgoECDSA256, KeyAlgoECDSA384, KeyAlgoECDSA521,
+	case KeyAlgoRSA, KeyAlgoDSA, KeyAlgoECDSA256, KeyAlgoECDSA384, KeyAlgoECDSA521, KeyAlgoED25519,
 		CertAlgoRSAv01, CertAlgoDSAv01, CertAlgoECDSA256v01, CertAlgoECDSA384v01, CertAlgoECDSA521v01:
 		return true
 	}
 	return false
 }

-func checkSourceAddress(addr net.Addr, sourceAddr string) error {
+func checkSourceAddress(addr net.Addr, sourceAddrs string) error {
 	if addr == nil {
 		return errors.New("ssh: no address known for client, but source-address match required")
 	}
@@ -247,33 +268,71 @@ func checkSourceAddress(addr net.Addr, sourceAddr string) error {
 		return fmt.Errorf("ssh: remote address %v is not an TCP address when checking source-address match", addr)
 	}

-	if allowedIP := net.ParseIP(sourceAddr); allowedIP != nil {
-		if bytes.Equal(allowedIP, tcpAddr.IP) {
-			return nil
-		}
-	} else {
-		_, ipNet, err := net.ParseCIDR(sourceAddr)
-		if err != nil {
-			return fmt.Errorf("ssh: error parsing source-address restriction %q: %v", sourceAddr, err)
-		}
+	for _, sourceAddr := range strings.Split(sourceAddrs, ",") {
+		if allowedIP := net.ParseIP(sourceAddr); allowedIP != nil {
+			if allowedIP.Equal(tcpAddr.IP) {
+				return nil
+			}
+		} else {
+			_, ipNet, err := net.ParseCIDR(sourceAddr)
+			if err != nil {
+				return fmt.Errorf("ssh: error parsing source-address restriction %q: %v", sourceAddr, err)
+			}

-		if ipNet.Contains(tcpAddr.IP) {
-			return nil
+			if ipNet.Contains(tcpAddr.IP) {
+				return nil
+			}
 		}
 	}

 	return fmt.Errorf("ssh: remote address %v is not allowed because of source-address restriction", addr)
 }

+// ServerAuthError implements the error interface. It appends any authentication
+// errors that may occur, and is returned if all of the authentication methods
+// provided by the user failed to authenticate.
+type ServerAuthError struct {
+	// Errors contains authentication errors returned by the authentication
+	// callback methods.
+	Errors []error
+}
+
+func (l ServerAuthError) Error() string {
+	var errs []string
+	for _, err := range l.Errors {
+		errs = append(errs, err.Error())
+	}
+	return "[" + strings.Join(errs, ", ") + "]"
+}
+
 func (s *connection) serverAuthenticate(config *ServerConfig) (*Permissions, error) {
-	var err error
+	sessionID := s.transport.getSessionID()
 	var cache pubKeyCache
 	var perms *Permissions

+	authFailures := 0
+	var authErrs []error
+
 userAuthLoop:
 	for {
+		if authFailures >= config.MaxAuthTries && config.MaxAuthTries > 0 {
+			discMsg := &disconnectMsg{
+				Reason:  2,
+				Message: "too many authentication failures",
+			}
+
+			if err := s.transport.writePacket(Marshal(discMsg)); err != nil {
+				return nil, err
+			}
+
+			return nil, discMsg
+		}
+
 		var userAuthReq userAuthRequestMsg
 		if packet, err := s.transport.readPacket(); err != nil {
+			if err == io.EOF {
+				return nil, &ServerAuthError{Errors: authErrs}
+			}
 			return nil, err
 		} else if err = Unmarshal(packet, &userAuthReq); err != nil {
 			return nil, err
@@ -290,9 +349,13 @@ userAuthLoop:
 		switch userAuthReq.Method {
 		case "none":
 			if config.NoClientAuth {
-				s.user = ""
 				authErr = nil
 			}
+
+			// allow initial attempt of 'none' without penalty
+			if authFailures == 0 {
+				authFailures--
+			}
 		case "password":
 			if config.PasswordCallback == nil {
 				authErr = errors.New("ssh: password auth not configured")
@@ -364,6 +427,7 @@ userAuthLoop:
 			if isQuery {
 				// The client can query if the given public key
 				// would be okay.
+
 				if len(payload) > 0 {
 					return nil, parseError(msgUserAuthRequest)
 				}
@@ -392,7 +456,7 @@ userAuthLoop:
 				if !isAcceptableAlgo(sig.Format) {
 					break
 				}
-				signedData := buildDataSignedForAuth(s.transport.getSessionID(), userAuthReq, algoBytes, pubKeyData)
+				signedData := buildDataSignedForAuth(sessionID, userAuthReq, algoBytes, pubKeyData)

 				if err := pubKey.Verify(signedData, sig); err != nil {
 					return nil, err
@@ -405,6 +469,8 @@ userAuthLoop:
 			authErr = fmt.Errorf("ssh: unknown method %q", userAuthReq.Method)
 		}

+		authErrs = append(authErrs, authErr)
+
 		if config.AuthLogCallback != nil {
 			config.AuthLogCallback(s, userAuthReq.Method, authErr)
 		}
@@ -413,6 +479,8 @@ userAuthLoop:
 			break userAuthLoop
 		}

+		authFailures++
+
 		var failureMsg userAuthFailureMsg
 		if config.PasswordCallback != nil {
 			failureMsg.Methods = append(failureMsg.Methods, "password")
@@ -428,12 +496,12 @@ userAuthLoop:
 			return nil, errors.New("ssh: no authentication methods configured but NoClientAuth is also false")
 		}

-		if err = s.transport.writePacket(Marshal(&failureMsg)); err != nil {
+		if err := s.transport.writePacket(Marshal(&failureMsg)); err != nil {
 			return nil, err
 		}
 	}

-	if err = s.transport.writePacket([]byte{msgUserAuthSuccess}); err != nil {
+	if err := s.transport.writePacket([]byte{msgUserAuthSuccess}); err != nil {
 		return nil, err
 	}
 	return perms, nil
@@ -9,6 +9,7 @@ package ssh

 import (
 	"bytes"
+	"encoding/binary"
 	"errors"
 	"fmt"
 	"io"
@@ -281,9 +282,10 @@ func (s *Session) Start(cmd string) error {
 // copying stdin, stdout, and stderr, and exits with a zero exit
 // status.
 //
-// If the command fails to run or doesn't complete successfully, the
-// error is of type *ExitError. Other error types may be
-// returned for I/O problems.
+// If the remote server does not send an exit status, an error of type
+// *ExitMissingError is returned. If the command completes
+// unsuccessfully or is interrupted by a signal, the error is of type
+// *ExitError. Other error types may be returned for I/O problems.
 func (s *Session) Run(cmd string) error {
 	err := s.Start(cmd)
 	if err != nil {
@@ -370,9 +372,10 @@ func (s *Session) start() error {
 // copying stdin, stdout, and stderr, and exits with a zero exit
 // status.
 //
-// If the command fails to run or doesn't complete successfully, the
-// error is of type *ExitError. Other error types may be
-// returned for I/O problems.
+// If the remote server does not send an exit status, an error of type
+// *ExitMissingError is returned. If the command completes
+// unsuccessfully or is interrupted by a signal, the error is of type
+// *ExitError. Other error types may be returned for I/O problems.
 func (s *Session) Wait() error {
 	if !s.started {
 		return errors.New("ssh: session not started")
@@ -400,8 +403,7 @@ func (s *Session) wait(reqs <-chan *Request) error {
 	for msg := range reqs {
 		switch msg.Type {
 		case "exit-status":
-			d := msg.Payload
-			wm.status = int(d[0])<<24 | int(d[1])<<16 | int(d[2])<<8 | int(d[3])
+			wm.status = int(binary.BigEndian.Uint32(msg.Payload))
 		case "exit-signal":
 			var sigval struct {
 				Signal     string
@@ -431,16 +433,29 @@ func (s *Session) wait(reqs <-chan *Request) error {
 	if wm.status == -1 {
 		// exit-status was never sent from server
 		if wm.signal == "" {
-			return errors.New("wait: remote command exited without exit status or exit signal")
+			// signal was not sent either.  RFC 4254
+			// section 6.10 recommends against this
+			// behavior, but it is allowed, so we let
+			// clients handle it.
+			return &ExitMissingError{}
 		}
 		wm.status = 128
 		if _, ok := signals[Signal(wm.signal)]; ok {
 			wm.status += signals[Signal(wm.signal)]
 		}
 	}
+
 	return &ExitError{wm}
 }

+// ExitMissingError is returned if a session is torn down cleanly, but
+// the server sends no confirmation of the exit status.
+type ExitMissingError struct{}
+
+func (e *ExitMissingError) Error() string {
+	return "wait: remote command exited without exit status or exit signal"
+}
+
 func (s *Session) stdin() {
 	if s.stdinpipe {
 		return
@@ -601,5 +616,12 @@ func (w Waitmsg) Lang() string {
 }

 func (w Waitmsg) String() string {
-	return fmt.Sprintf("Process exited with: %v. Reason was: %v (%v)", w.status, w.msg, w.signal)
+	str := fmt.Sprintf("Process exited with status %v", w.status)
+	if w.signal != "" {
+		str += fmt.Sprintf(" from signal %v", w.signal)
+	}
+	if w.msg != "" {
+		str += fmt.Sprintf(". Reason was: %v", w.msg)
+	}
+	return str
 }
@@ -0,0 +1,115 @@
+package ssh
+
+import (
+	"errors"
+	"io"
+	"net"
+)
+
+// streamLocalChannelOpenDirectMsg is a struct used for SSH_MSG_CHANNEL_OPEN message
+// with "direct-streamlocal@openssh.com" string.
+//
+// See openssh-portable/PROTOCOL, section 2.4. connection: Unix domain socket forwarding
+// https://github.com/openssh/openssh-portable/blob/master/PROTOCOL#L235
+type streamLocalChannelOpenDirectMsg struct {
+	socketPath string
+	reserved0  string
+	reserved1  uint32
+}
+
+// forwardedStreamLocalPayload is a struct used for SSH_MSG_CHANNEL_OPEN message
+// with "forwarded-streamlocal@openssh.com" string.
+type forwardedStreamLocalPayload struct {
+	SocketPath string
+	Reserved0  string
+}
+
+// streamLocalChannelForwardMsg is a struct used for SSH2_MSG_GLOBAL_REQUEST message
+// with "streamlocal-forward@openssh.com"/"cancel-streamlocal-forward@openssh.com" string.
+type streamLocalChannelForwardMsg struct {
+	socketPath string
+}
+
+// ListenUnix is similar to ListenTCP but uses a Unix domain socket.
+func (c *Client) ListenUnix(socketPath string) (net.Listener, error) {
+	m := streamLocalChannelForwardMsg{
+		socketPath,
+	}
+	// send message
+	ok, _, err := c.SendRequest("streamlocal-forward@openssh.com", true, Marshal(&m))
+	if err != nil {
+		return nil, err
+	}
+	if !ok {
+		return nil, errors.New("ssh: streamlocal-forward@openssh.com request denied by peer")
+	}
+	ch := c.forwards.add(&net.UnixAddr{Name: socketPath, Net: "unix"})
+
+	return &unixListener{socketPath, c, ch}, nil
+}
+
+func (c *Client) dialStreamLocal(socketPath string) (Channel, error) {
+	msg := streamLocalChannelOpenDirectMsg{
+		socketPath: socketPath,
+	}
+	ch, in, err := c.OpenChannel("direct-streamlocal@openssh.com", Marshal(&msg))
+	if err != nil {
+		return nil, err
+	}
+	go DiscardRequests(in)
+	return ch, err
+}
+
+type unixListener struct {
+	socketPath string
+
+	conn *Client
+	in   <-chan forward
+}
+
+// Accept waits for and returns the next connection to the listener.
+func (l *unixListener) Accept() (net.Conn, error) {
+	s, ok := <-l.in
+	if !ok {
+		return nil, io.EOF
+	}
+	ch, incoming, err := s.newCh.Accept()
+	if err != nil {
+		return nil, err
+	}
+	go DiscardRequests(incoming)
+
+	return &chanConn{
+		Channel: ch,
+		laddr: &net.UnixAddr{
+			Name: l.socketPath,
+			Net:  "unix",
+		},
+		raddr: &net.UnixAddr{
+			Name: "@",
+			Net:  "unix",
+		},
+	}, nil
+}
+
+// Close closes the listener.
+func (l *unixListener) Close() error {
+	// this also closes the listener.
+	l.conn.forwards.remove(&net.UnixAddr{Name: l.socketPath, Net: "unix"})
+	m := streamLocalChannelForwardMsg{
+		l.socketPath,
+	}
+	ok, _, err := l.conn.SendRequest("cancel-streamlocal-forward@openssh.com", true, Marshal(&m))
+	if err == nil && !ok {
+		err = errors.New("ssh: cancel-streamlocal-forward@openssh.com failed")
+	}
+	return err
+}
+
+// Addr returns the listener's network address.
+func (l *unixListener) Addr() net.Addr {
+	return &net.UnixAddr{
+		Name: l.socketPath,
+		Net:  "unix",
+	}
+}
@@ -20,12 +20,20 @@ import (
 // addr. Incoming connections will be available by calling Accept on
 // the returned net.Listener. The listener must be serviced, or the
 // SSH connection may hang.
+// N must be "tcp", "tcp4", "tcp6", or "unix".
 func (c *Client) Listen(n, addr string) (net.Listener, error) {
-	laddr, err := net.ResolveTCPAddr(n, addr)
-	if err != nil {
-		return nil, err
+	switch n {
+	case "tcp", "tcp4", "tcp6":
+		laddr, err := net.ResolveTCPAddr(n, addr)
+		if err != nil {
+			return nil, err
+		}
+		return c.ListenTCP(laddr)
+	case "unix":
+		return c.ListenUnix(addr)
+	default:
+		return nil, fmt.Errorf("ssh: unsupported protocol: %s", n)
 	}
-	return c.ListenTCP(laddr)
 }

 // Automatic port allocation is broken with OpenSSH before 6.0. See
@@ -116,7 +124,7 @@ func (c *Client) ListenTCP(laddr *net.TCPAddr) (net.Listener, error) {
 	}

 	// Register this forward, using the port number we obtained.
-	ch := c.forwards.add(*laddr)
+	ch := c.forwards.add(laddr)

 	return &tcpListener{laddr, c, ch}, nil
 }
@@ -131,7 +139,7 @@ type forwardList struct {
 // forwardEntry represents an established mapping of a laddr on a
 // remote ssh server to a channel connected to a tcpListener.
 type forwardEntry struct {
-	laddr net.TCPAddr
+	laddr net.Addr
 	c     chan forward
 }

@@ -139,16 +147,16 @@ type forwardEntry struct {
 // arguments to add/remove/lookup should be address as specified in
 // the original forward-request.
 type forward struct {
-	newCh NewChannel   // the ssh client channel underlying this forward
-	raddr *net.TCPAddr // the raddr of the incoming connection
+	newCh NewChannel // the ssh client channel underlying this forward
+	raddr net.Addr   // the raddr of the incoming connection
 }

-func (l *forwardList) add(addr net.TCPAddr) chan forward {
+func (l *forwardList) add(addr net.Addr) chan forward {
 	l.Lock()
 	defer l.Unlock()
 	f := forwardEntry{
-		addr,
-		make(chan forward, 1),
+		laddr: addr,
+		c:     make(chan forward, 1),
 	}
 	l.entries = append(l.entries, f)
 	return f.c
@@ -176,44 +184,69 @@ func parseTCPAddr(addr string, port uint32) (*net.TCPAddr, error) {

 func (l *forwardList) handleChannels(in <-chan NewChannel) {
 	for ch := range in {
-		var payload forwardedTCPPayload
-		if err := Unmarshal(ch.ExtraData(), &payload); err != nil {
-			ch.Reject(ConnectionFailed, "could not parse forwarded-tcpip payload: "+err.Error())
-			continue
-		}
+		var (
+			laddr net.Addr
+			raddr net.Addr
+			err   error
+		)
+		switch channelType := ch.ChannelType(); channelType {
+		case "forwarded-tcpip":
+			var payload forwardedTCPPayload
+			if err = Unmarshal(ch.ExtraData(), &payload); err != nil {
+				ch.Reject(ConnectionFailed, "could not parse forwarded-tcpip payload: "+err.Error())
+				continue
+			}

-		// RFC 4254 section 7.2 specifies that incoming
-		// addresses should list the address, in string
-		// format. It is implied that this should be an IP
-		// address, as it would be impossible to connect to it
-		// otherwise.
-		laddr, err := parseTCPAddr(payload.Addr, payload.Port)
-		if err != nil {
-			ch.Reject(ConnectionFailed, err.Error())
-			continue
-		}
-		raddr, err := parseTCPAddr(payload.OriginAddr, payload.OriginPort)
-		if err != nil {
-			ch.Reject(ConnectionFailed, err.Error())
-			continue
-		}
+			// RFC 4254 section 7.2 specifies that incoming
+			// addresses should list the address, in string
+			// format. It is implied that this should be an IP
+			// address, as it would be impossible to connect to it
+			// otherwise.
+			laddr, err = parseTCPAddr(payload.Addr, payload.Port)
+			if err != nil {
+				ch.Reject(ConnectionFailed, err.Error())
+				continue
+			}
+			raddr, err = parseTCPAddr(payload.OriginAddr, payload.OriginPort)
+			if err != nil {
+				ch.Reject(ConnectionFailed, err.Error())
+				continue
+			}

-		if ok := l.forward(*laddr, *raddr, ch); !ok {
+		case "forwarded-streamlocal@openssh.com":
+			var payload forwardedStreamLocalPayload
+			if err = Unmarshal(ch.ExtraData(), &payload); err != nil {
+				ch.Reject(ConnectionFailed, "could not parse forwarded-streamlocal@openssh.com payload: "+err.Error())
+				continue
+			}
+			laddr = &net.UnixAddr{
+				Name: payload.SocketPath,
+				Net:  "unix",
+			}
+			raddr = &net.UnixAddr{
+				Name: "@",
+				Net:  "unix",
+			}
+		default:
+			panic(fmt.Errorf("ssh: unknown channel type %s", channelType))
+		}
+		if ok := l.forward(laddr, raddr, ch); !ok {
 			// Section 7.2, implementations MUST reject spurious incoming
 			// connections.
 			ch.Reject(Prohibited, "no forward for address")
 			continue
 		}
+
 	}
 }

 // remove removes the forward entry, and the channel feeding its
 // listener.
-func (l *forwardList) remove(addr net.TCPAddr) {
+func (l *forwardList) remove(addr net.Addr) {
 	l.Lock()
 	defer l.Unlock()
 	for i, f := range l.entries {
-		if addr.IP.Equal(f.laddr.IP) && addr.Port == f.laddr.Port {
+		if addr.Network() == f.laddr.Network() && addr.String() == f.laddr.String() {
 			l.entries = append(l.entries[:i], l.entries[i+1:]...)
 			close(f.c)
 			return
@@ -231,12 +264,12 @@ func (l *forwardList) closeAll() {
 	l.entries = nil
 }

-func (l *forwardList) forward(laddr, raddr net.TCPAddr, ch NewChannel) bool {
+func (l *forwardList) forward(laddr, raddr net.Addr, ch NewChannel) bool {
 	l.Lock()
 	defer l.Unlock()
 	for _, f := range l.entries {
-		if laddr.IP.Equal(f.laddr.IP) && laddr.Port == f.laddr.Port {
-			f.c <- forward{ch, &raddr}
+		if laddr.Network() == f.laddr.Network() && laddr.String() == f.laddr.String() {
+			f.c <- forward{newCh: ch, raddr: raddr}
 			return true
 		}
 	}
@@ -262,7 +295,7 @@ func (l *tcpListener) Accept() (net.Conn, error) {
 	}
 	go DiscardRequests(incoming)

-	return &tcpChanConn{
+	return &chanConn{
 		Channel: ch,
 		laddr:   l.laddr,
 		raddr:   s.raddr,
@@ -277,7 +310,7 @@ func (l *tcpListener) Close() error {
 	}

 	// this also closes the listener.
-	l.conn.forwards.remove(*l.laddr)
+	l.conn.forwards.remove(l.laddr)
 	ok, _, err := l.conn.SendRequest("cancel-tcpip-forward", true, Marshal(&m))
 	if err == nil && !ok {
 		err = errors.New("ssh: cancel-tcpip-forward failed")
@@ -293,29 +326,52 @@ func (l *tcpListener) Addr() net.Addr {
 // Dial initiates a connection to the addr from the remote host.
 // The resulting connection has a zero LocalAddr() and RemoteAddr().
 func (c *Client) Dial(n, addr string) (net.Conn, error) {
-	// Parse the address into host and numeric port.
-	host, portString, err := net.SplitHostPort(addr)
-	if err != nil {
-		return nil, err
+	var ch Channel
+	switch n {
+	case "tcp", "tcp4", "tcp6":
+		// Parse the address into host and numeric port.
+		host, portString, err := net.SplitHostPort(addr)
+		if err != nil {
+			return nil, err
+		}
+		port, err := strconv.ParseUint(portString, 10, 16)
+		if err != nil {
+			return nil, err
+		}
+		ch, err = c.dial(net.IPv4zero.String(), 0, host, int(port))
+		if err != nil {
+			return nil, err
+		}
+		// Use a zero address for local and remote address.
+		zeroAddr := &net.TCPAddr{
+			IP:   net.IPv4zero,
+			Port: 0,
+		}
+		return &chanConn{
+			Channel: ch,
+			laddr:   zeroAddr,
+			raddr:   zeroAddr,
+		}, nil
+	case "unix":
+		var err error
+		ch, err = c.dialStreamLocal(addr)
+		if err != nil {
+			return nil, err
+		}
+		return &chanConn{
+			Channel: ch,
+			laddr: &net.UnixAddr{
+				Name: "@",
+				Net:  "unix",
+			},
+			raddr: &net.UnixAddr{
+				Name: addr,
+				Net:  "unix",
+			},
+		}, nil
+	default:
+		return nil, fmt.Errorf("ssh: unsupported protocol: %s", n)
 	}
-	port, err := strconv.ParseUint(portString, 10, 16)
-	if err != nil {
-		return nil, err
-	}
-	// Use a zero address for local and remote address.
-	zeroAddr := &net.TCPAddr{
-		IP:   net.IPv4zero,
-		Port: 0,
-	}
-	ch, err := c.dial(net.IPv4zero.String(), 0, host, int(port))
-	if err != nil {
-		return nil, err
-	}
-	return &tcpChanConn{
-		Channel: ch,
-		laddr:   zeroAddr,
-		raddr:   zeroAddr,
-	}, nil
 }

 // DialTCP connects to the remote address raddr on the network net,
@@ -332,7 +388,7 @@ func (c *Client) DialTCP(n string, laddr, raddr *net.TCPAddr) (net.Conn, error)
 	if err != nil {
 		return nil, err
 	}
-	return &tcpChanConn{
+	return &chanConn{
 		Channel: ch,
 		laddr:   laddr,
 		raddr:   raddr,
@@ -366,26 +422,26 @@ type tcpChan struct {
 	Channel // the backing channel
 }

-// tcpChanConn fulfills the net.Conn interface without
+// chanConn fulfills the net.Conn interface without
 // the tcpChan having to hold laddr or raddr directly.
-type tcpChanConn struct {
+type chanConn struct {
 	Channel
 	laddr, raddr net.Addr
 }

 // LocalAddr returns the local network address.
-func (t *tcpChanConn) LocalAddr() net.Addr {
+func (t *chanConn) LocalAddr() net.Addr {
 	return t.laddr
 }

 // RemoteAddr returns the remote network address.
-func (t *tcpChanConn) RemoteAddr() net.Addr {
+func (t *chanConn) RemoteAddr() net.Addr {
 	return t.raddr
 }

 // SetDeadline sets the read and write deadlines associated
 // with the connection.
-func (t *tcpChanConn) SetDeadline(deadline time.Time) error {
+func (t *chanConn) SetDeadline(deadline time.Time) error {
 	if err := t.SetReadDeadline(deadline); err != nil {
 		return err
 	}
@@ -396,12 +452,14 @@ func (t *tcpChanConn) SetDeadline(deadline time.Time) error {
 // A zero value for t means Read will not time out.
 // After the deadline, the error from Read will implement net.Error
 // with Timeout() == true.
-func (t *tcpChanConn) SetReadDeadline(deadline time.Time) error {
+func (t *chanConn) SetReadDeadline(deadline time.Time) error {
+	// for compatibility with previous version,
+	// the error message contains "tcpChan"
 	return errors.New("ssh: tcpChan: deadline not supported")
 }

 // SetWriteDeadline exists to satisfy the net.Conn interface
 // but is not implemented by this type.  It always returns an error.
-func (t *tcpChanConn) SetWriteDeadline(deadline time.Time) error {
+func (t *chanConn) SetWriteDeadline(deadline time.Time) error {
 	return errors.New("ssh: tcpChan: deadline not supported")
 }
@@ -132,8 +132,11 @@ const (
 	keyPasteEnd
 )

-var pasteStart = []byte{keyEscape, '[', '2', '0', '0', '~'}
-var pasteEnd = []byte{keyEscape, '[', '2', '0', '1', '~'}
+var (
+	crlf       = []byte{'\r', '\n'}
+	pasteStart = []byte{keyEscape, '[', '2', '0', '0', '~'}
+	pasteEnd   = []byte{keyEscape, '[', '2', '0', '1', '~'}
+)

 // bytesToKey tries to parse a key sequence from b. If successful, it returns
 // the key and the remainder of the input. Otherwise it returns utf8.RuneError.
@@ -333,7 +336,7 @@ func (t *Terminal) advanceCursor(places int) {
 		// So, if we are stopping at the end of a line, we
 		// need to write a newline so that our cursor can be
 		// advanced to the next line.
-		t.outBuf = append(t.outBuf, '\n')
+		t.outBuf = append(t.outBuf, '\r', '\n')
 	}
 }

@@ -593,6 +596,35 @@ func (t *Terminal) writeLine(line []rune) {
 	}
 }

+// writeWithCRLF writes buf to w but replaces all occurrences of \n with \r\n.
+func writeWithCRLF(w io.Writer, buf []byte) (n int, err error) {
+	for len(buf) > 0 {
+		i := bytes.IndexByte(buf, '\n')
+		todo := len(buf)
+		if i >= 0 {
+			todo = i
+		}
+
+		var nn int
+		nn, err = w.Write(buf[:todo])
+		n += nn
+		if err != nil {
+			return n, err
+		}
+		buf = buf[todo:]
+
+		if i >= 0 {
+			if _, err = w.Write(crlf); err != nil {
+				return n, err
+			}
+			n += 1
+			buf = buf[1:]
+		}
+	}
+
+	return n, nil
+}
+
 func (t *Terminal) Write(buf []byte) (n int, err error) {
 	t.lock.Lock()
 	defer t.lock.Unlock()
@@ -600,7 +632,7 @@ func (t *Terminal) Write(buf []byte) (n int, err error) {
 	if t.cursorX == 0 && t.cursorY == 0 {
 		// This is the easy case: there's nothing on the screen that we
 		// have to move out of the way.
-		return t.c.Write(buf)
+		return writeWithCRLF(t.c, buf)
 	}

 	// We have a prompt and possibly user input on the screen. We
@@ -620,7 +652,7 @@ func (t *Terminal) Write(buf []byte) (n int, err error) {
 	}
 	t.outBuf = t.outBuf[:0]

-	if n, err = t.c.Write(buf); err != nil {
+	if n, err = writeWithCRLF(t.c, buf); err != nil {
 		return
 	}

@@ -740,8 +772,6 @@ func (t *Terminal) readLine() (line string, err error) {

 		t.remainder = t.inBuf[:n+len(t.remainder)]
 	}
-
-	panic("unreachable") // for Go 1.0.
 }

 // SetPrompt sets the prompt to be used when reading subsequent lines.
@@ -890,3 +920,32 @@ func (s *stRingBuffer) NthPreviousEntry(n int) (value string, ok bool) {
 	}
 	return s.entries[index], true
 }
+
+// readPasswordLine reads from reader until it finds \n or io.EOF.
+// The slice returned does not include the \n.
+// readPasswordLine also ignores any \r it finds.
+func readPasswordLine(reader io.Reader) ([]byte, error) {
+	var buf [1]byte
+	var ret []byte
+
+	for {
+		n, err := reader.Read(buf[:])
+		if n > 0 {
+			switch buf[0] {
+			case '\n':
+				return ret, nil
+			case '\r':
+				// remove \r from passwords on Windows
+			default:
+				ret = append(ret, buf[0])
+			}
+			continue
+		}
+		if err != nil {
+			if err == io.EOF && len(ret) > 0 {
+				return ret, nil
+			}
+			return ret, err
+		}
+	}
+}
@@ -17,7 +17,6 @@
 package terminal

 import (
-	"io"
 	"syscall"
 	"unsafe"
 )
@@ -44,8 +43,13 @@ func MakeRaw(fd int) (*State, error) {
 	}

 	newState := oldState.termios
-	newState.Iflag &^= syscall.ISTRIP | syscall.INLCR | syscall.ICRNL | syscall.IGNCR | syscall.IXON | syscall.IXOFF
-	newState.Lflag &^= syscall.ECHO | syscall.ICANON | syscall.ISIG
+	// This attempts to replicate the behaviour documented for cfmakeraw in
+	// the termios(3) manpage.
+	newState.Iflag &^= syscall.IGNBRK | syscall.BRKINT | syscall.PARMRK | syscall.ISTRIP | syscall.INLCR | syscall.IGNCR | syscall.ICRNL | syscall.IXON
+	newState.Oflag &^= syscall.OPOST
+	newState.Lflag &^= syscall.ECHO | syscall.ECHONL | syscall.ICANON | syscall.ISIG | syscall.IEXTEN
+	newState.Cflag &^= syscall.CSIZE | syscall.PARENB
+	newState.Cflag |= syscall.CS8
 	if _, _, err := syscall.Syscall6(syscall.SYS_IOCTL, uintptr(fd), ioctlWriteTermios, uintptr(unsafe.Pointer(&newState)), 0, 0, 0); err != 0 {
 		return nil, err
 	}
@@ -67,8 +71,10 @@ func GetState(fd int) (*State, error) {
 // Restore restores the terminal connected to the given file descriptor to a
 // previous state.
 func Restore(fd int, state *State) error {
-	_, _, err := syscall.Syscall6(syscall.SYS_IOCTL, uintptr(fd), ioctlWriteTermios, uintptr(unsafe.Pointer(&state.termios)), 0, 0, 0)
-	return err
+	if _, _, err := syscall.Syscall6(syscall.SYS_IOCTL, uintptr(fd), ioctlWriteTermios, uintptr(unsafe.Pointer(&state.termios)), 0, 0, 0); err != 0 {
+		return err
+	}
+	return nil
 }

 // GetSize returns the dimensions of the given terminal.
@@ -81,6 +87,13 @@ func GetSize(fd int) (width, height int, err error) {
 	return int(dimensions[1]), int(dimensions[0]), nil
 }

+// passwordReader is an io.Reader that reads from a specific file descriptor.
+type passwordReader int
+
+func (r passwordReader) Read(buf []byte) (int, error) {
+	return syscall.Read(int(r), buf)
+}
+
 // ReadPassword reads a line of input from a terminal without local echo.  This
 // is commonly used for inputting passwords and other sensitive data. The slice
 // returned does not include the \n.
@@ -102,27 +115,5 @@ func ReadPassword(fd int) ([]byte, error) {
 		syscall.Syscall6(syscall.SYS_IOCTL, uintptr(fd), ioctlWriteTermios, uintptr(unsafe.Pointer(&oldState)), 0, 0, 0)
 	}()

-	var buf [16]byte
-	var ret []byte
-	for {
-		n, err := syscall.Read(fd, buf[:])
-		if err != nil {
-			return nil, err
-		}
-		if n == 0 {
-			if len(ret) == 0 {
-				return nil, io.EOF
-			}
-			break
-		}
-		if buf[n-1] == '\n' {
-			n--
-		}
-		ret = append(ret, buf[:n]...)
-		if n < len(buf) {
-			break
-		}
-	}
-
-	return ret, nil
+	return readPasswordLine(passwordReader(fd))
 }
@@ -0,0 +1,58 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package terminal provides support functions for dealing with terminals, as
+// commonly found on UNIX systems.
+//
+// Putting a terminal into raw mode is the most common requirement:
+//
+// 	oldState, err := terminal.MakeRaw(0)
+// 	if err != nil {
+// 	        panic(err)
+// 	}
+// 	defer terminal.Restore(0, oldState)
+package terminal
+
+import (
+	"fmt"
+	"runtime"
+)
+
+type State struct{}
+
+// IsTerminal returns true if the given file descriptor is a terminal.
+func IsTerminal(fd int) bool {
+	return false
+}
+
+// MakeRaw put the terminal connected to the given file descriptor into raw
+// mode and returns the previous state of the terminal so that it can be
+// restored.
+func MakeRaw(fd int) (*State, error) {
+	return nil, fmt.Errorf("terminal: MakeRaw not implemented on %s/%s", runtime.GOOS, runtime.GOARCH)
+}
+
+// GetState returns the current state of a terminal which may be useful to
+// restore the terminal after a signal.
+func GetState(fd int) (*State, error) {
+	return nil, fmt.Errorf("terminal: GetState not implemented on %s/%s", runtime.GOOS, runtime.GOARCH)
+}
+
+// Restore restores the terminal connected to the given file descriptor to a
+// previous state.
+func Restore(fd int, state *State) error {
+	return fmt.Errorf("terminal: Restore not implemented on %s/%s", runtime.GOOS, runtime.GOARCH)
+}
+
+// GetSize returns the dimensions of the given terminal.
+func GetSize(fd int) (width, height int, err error) {
+	return 0, 0, fmt.Errorf("terminal: GetSize not implemented on %s/%s", runtime.GOOS, runtime.GOARCH)
+}
+
+// ReadPassword reads a line of input from a terminal without local echo.  This
+// is commonly used for inputting passwords and other sensitive data. The slice
+// returned does not include the \n.
+func ReadPassword(fd int) ([]byte, error) {
+	return nil, fmt.Errorf("terminal: ReadPassword not implemented on %s/%s", runtime.GOOS, runtime.GOARCH)
+}
@@ -0,0 +1,128 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build solaris
+
+package terminal
+
+import (
+	"golang.org/x/sys/unix"
+	"io"
+	"syscall"
+)
+
+// State contains the state of a terminal.
+type State struct {
+	state *unix.Termios
+}
+
+// IsTerminal returns true if the given file descriptor is a terminal.
+func IsTerminal(fd int) bool {
+	_, err := unix.IoctlGetTermio(fd, unix.TCGETA)
+	return err == nil
+}
+
+// ReadPassword reads a line of input from a terminal without local echo.  This
+// is commonly used for inputting passwords and other sensitive data. The slice
+// returned does not include the \n.
+func ReadPassword(fd int) ([]byte, error) {
+	// see also: http://src.illumos.org/source/xref/illumos-gate/usr/src/lib/libast/common/uwin/getpass.c
+	val, err := unix.IoctlGetTermios(fd, unix.TCGETS)
+	if err != nil {
+		return nil, err
+	}
+	oldState := *val
+
+	newState := oldState
+	newState.Lflag &^= syscall.ECHO
+	newState.Lflag |= syscall.ICANON | syscall.ISIG
+	newState.Iflag |= syscall.ICRNL
+	err = unix.IoctlSetTermios(fd, unix.TCSETS, &newState)
+	if err != nil {
+		return nil, err
+	}
+
+	defer unix.IoctlSetTermios(fd, unix.TCSETS, &oldState)
+
+	var buf [16]byte
+	var ret []byte
+	for {
+		n, err := syscall.Read(fd, buf[:])
+		if err != nil {
+			return nil, err
+		}
+		if n == 0 {
+			if len(ret) == 0 {
+				return nil, io.EOF
+			}
+			break
+		}
+		if buf[n-1] == '\n' {
+			n--
+		}
+		ret = append(ret, buf[:n]...)
+		if n < len(buf) {
+			break
+		}
+	}
+
+	return ret, nil
+}
+
+// MakeRaw puts the terminal connected to the given file descriptor into raw
+// mode and returns the previous state of the terminal so that it can be
+// restored.
+// see http://cr.illumos.org/~webrev/andy_js/1060/
+func MakeRaw(fd int) (*State, error) {
+	oldTermiosPtr, err := unix.IoctlGetTermios(fd, unix.TCGETS)
+	if err != nil {
+		return nil, err
+	}
+	oldTermios := *oldTermiosPtr
+
+	newTermios := oldTermios
+	newTermios.Iflag &^= syscall.IGNBRK | syscall.BRKINT | syscall.PARMRK | syscall.ISTRIP | syscall.INLCR | syscall.IGNCR | syscall.ICRNL | syscall.IXON
+	newTermios.Oflag &^= syscall.OPOST
+	newTermios.Lflag &^= syscall.ECHO | syscall.ECHONL | syscall.ICANON | syscall.ISIG | syscall.IEXTEN
+	newTermios.Cflag &^= syscall.CSIZE | syscall.PARENB
+	newTermios.Cflag |= syscall.CS8
+	newTermios.Cc[unix.VMIN] = 1
+	newTermios.Cc[unix.VTIME] = 0
+
+	if err := unix.IoctlSetTermios(fd, unix.TCSETS, &newTermios); err != nil {
+		return nil, err
+	}
+
+	return &State{
+		state: oldTermiosPtr,
+	}, nil
+}
+
+// Restore restores the terminal connected to the given file descriptor to a
+// previous state.
+func Restore(fd int, oldState *State) error {
+	return unix.IoctlSetTermios(fd, unix.TCSETS, oldState.state)
+}
+
+// GetState returns the current state of a terminal which may be useful to
+// restore the terminal after a signal.
+func GetState(fd int) (*State, error) {
+	oldTermiosPtr, err := unix.IoctlGetTermios(fd, unix.TCGETS)
+	if err != nil {
+		return nil, err
+	}
+
+	return &State{
+		state: oldTermiosPtr,
+	}, nil
+}
+
+// GetSize returns the dimensions of the given terminal.
+func GetSize(fd int) (width, height int, err error) {
+	ws, err := unix.IoctlGetWinsize(fd, unix.TIOCGWINSZ)
+	if err != nil {
+		return 0, 0, err
+	}
+	return int(ws.Col), int(ws.Row), nil
+}
@@ -17,7 +17,6 @@
 package terminal

 import (
-	"io"
 	"syscall"
 	"unsafe"
 )
@@ -87,8 +86,8 @@ func MakeRaw(fd int) (*State, error) {
 	if e != 0 {
 		return nil, error(e)
 	}
-	st &^= (enableEchoInput | enableProcessedInput | enableLineInput | enableProcessedOutput)
-	_, _, e = syscall.Syscall(procSetConsoleMode.Addr(), 2, uintptr(fd), uintptr(st), 0)
+	raw := st &^ (enableEchoInput | enableProcessedInput | enableLineInput | enableProcessedOutput)
+	_, _, e = syscall.Syscall(procSetConsoleMode.Addr(), 2, uintptr(fd), uintptr(raw), 0)
 	if e != 0 {
 		return nil, error(e)
 	}
@@ -123,6 +122,13 @@ func GetSize(fd int) (width, height int, err error) {
 	return int(info.size.x), int(info.size.y), nil
 }

+// passwordReader is an io.Reader that reads from a specific Windows HANDLE.
+type passwordReader int
+
+func (r passwordReader) Read(buf []byte) (int, error) {
+	return syscall.Read(syscall.Handle(r), buf)
+}
+
 // ReadPassword reads a line of input from a terminal without local echo.  This
 // is commonly used for inputting passwords and other sensitive data. The slice
 // returned does not include the \n.
@@ -145,30 +151,5 @@ func ReadPassword(fd int) ([]byte, error) {
 		syscall.Syscall(procSetConsoleMode.Addr(), 2, uintptr(fd), uintptr(old), 0)
 	}()

-	var buf [16]byte
-	var ret []byte
-	for {
-		n, err := syscall.Read(syscall.Handle(fd), buf[:])
-		if err != nil {
-			return nil, err
-		}
-		if n == 0 {
-			if len(ret) == 0 {
-				return nil, io.EOF
-			}
-			break
-		}
-		if buf[n-1] == '\n' {
-			n--
-		}
-		if n > 0 && buf[n-1] == '\r' {
-			n--
-		}
-		ret = append(ret, buf[:n]...)
-		if n < len(buf) {
-			break
-		}
-	}
-
-	return ret, nil
+	return readPasswordLine(passwordReader(fd))
 }
@@ -8,11 +8,17 @@ import (
 	"bufio"
 	"errors"
 	"io"
+	"log"
 )

+// debugTransport if set, will print packet types as they go over the
+// wire. No message decoding is done, to minimize the impact on timing.
+const debugTransport = false
+
 const (
-	gcmCipherID = "aes128-gcm@openssh.com"
-	aes128cbcID = "aes128-cbc"
+	gcmCipherID    = "aes128-gcm@openssh.com"
+	aes128cbcID    = "aes128-cbc"
+	tripledescbcID = "3des-cbc"
 )

 // packetConn represents a transport that implements packet based
@@ -21,7 +27,9 @@ type packetConn interface {
 	// Encrypt and send a packet of data to the remote peer.
 	writePacket(packet []byte) error

-	// Read a packet from the connection
+	// Read a packet from the connection. The read is blocking,
+	// i.e. if error is nil, then the returned byte slice is
+	// always non-empty.
 	readPacket() ([]byte, error)

 	// Close closes the write-side of the connection.
@@ -37,21 +45,8 @@ type transport struct {
 	bufReader *bufio.Reader
 	bufWriter *bufio.Writer
 	rand      io.Reader
-
+	isClient  bool
 	io.Closer
-
-	// Initial H used for the session ID. Once assigned this does
-	// not change, even during subsequent key exchanges.
-	sessionID []byte
-}
-
-// getSessionID returns the ID of the SSH connection. The return value
-// should not be modified.
-func (t *transport) getSessionID() []byte {
-	if t.sessionID == nil {
-		panic("session ID not set yet")
-	}
-	return t.sessionID
 }

 // packetCipher represents a combination of SSH encryption/MAC
@@ -81,12 +76,6 @@ type connectionState struct {
 // both directions are triggered by reading and writing a msgNewKey packet
 // respectively.
 func (t *transport) prepareKeyChange(algs *algorithms, kexResult *kexResult) error {
-	if t.sessionID == nil {
-		t.sessionID = kexResult.H
-	}
-
-	kexResult.SessionID = t.sessionID
-
 	if ciph, err := newPacketCipher(t.reader.dir, algs.r, kexResult); err != nil {
 		return err
 	} else {
@@ -102,9 +91,38 @@ func (t *transport) prepareKeyChange(algs *algorithms, kexResult *kexResult) err
 	return nil
 }

+func (t *transport) printPacket(p []byte, write bool) {
+	if len(p) == 0 {
+		return
+	}
+	who := "server"
+	if t.isClient {
+		who = "client"
+	}
+	what := "read"
+	if write {
+		what = "write"
+	}
+
+	log.Println(what, who, p[0])
+}
+
 // Read and decrypt next packet.
-func (t *transport) readPacket() ([]byte, error) {
-	return t.reader.readPacket(t.bufReader)
+func (t *transport) readPacket() (p []byte, err error) {
+	for {
+		p, err = t.reader.readPacket(t.bufReader)
+		if err != nil {
+			break
+		}
+		if len(p) == 0 || (p[0] != msgIgnore && p[0] != msgDebug) {
+			break
+		}
+	}
+	if debugTransport {
+		t.printPacket(p, false)
+	}
+
+	return p, err
 }

 func (s *connectionState) readPacket(r *bufio.Reader) ([]byte, error) {
@@ -114,12 +132,27 @@ func (s *connectionState) readPacket(r *bufio.Reader) ([]byte, error) {
 		err = errors.New("ssh: zero length packet")
 	}

-	if len(packet) > 0 && packet[0] == msgNewKeys {
-		select {
-		case cipher := <-s.pendingKeyChange:
-			s.packetCipher = cipher
-		default:
-			return nil, errors.New("ssh: got bogus newkeys message.")
+	if len(packet) > 0 {
+		switch packet[0] {
+		case msgNewKeys:
+			select {
+			case cipher := <-s.pendingKeyChange:
+				s.packetCipher = cipher
+			default:
+				return nil, errors.New("ssh: got bogus newkeys message.")
+			}
+
+		case msgDisconnect:
+			// Transform a disconnect message into an
+			// error. Since this is lowest level at which
+			// we interpret message types, doing it here
+			// ensures that we don't have to handle it
+			// elsewhere.
+			var msg disconnectMsg
+			if err := Unmarshal(packet, &msg); err != nil {
+				return nil, err
+			}
+			return nil, &msg
 		}
 	}

@@ -132,6 +165,9 @@ func (s *connectionState) readPacket(r *bufio.Reader) ([]byte, error) {
 }

 func (t *transport) writePacket(packet []byte) error {
+	if debugTransport {
+		t.printPacket(packet, true)
+	}
 	return t.writer.writePacket(t.bufWriter, t.rand, packet)
 }

@@ -172,6 +208,8 @@ func newTransport(rwc io.ReadWriteCloser, rand io.Reader, isClient bool) *transp
 		},
 		Closer: rwc,
 	}
+	t.isClient = isClient
+
 	if isClient {
 		t.reader.dir = serverKeys
 		t.writer.dir = clientKeys
@@ -223,8 +261,13 @@ func newPacketCipher(d direction, algs directionAlgorithms, kex *kexResult) (pac
 		return newAESCBCCipher(iv, key, macKey, algs)
 	}

+	if algs.Cipher == tripledescbcID {
+		return newTripleDESCBCCipher(iv, key, macKey, algs)
+	}
+
 	c := &streamPacketCipher{
 		mac: macModes[algs.MAC].new(macKey),
+		etm: macModes[algs.MAC].etm,
 	}
 	c.macResult = make([]byte, c.mac.Size())