diff --git a/communicator/ssh/provisioner.go b/communicator/ssh/provisioner.go
index 79d047727..69923017e 100644
--- a/communicator/ssh/provisioner.go
+++ b/communicator/ssh/provisioner.go
@@ -1,11 +1,15 @@
 package ssh
 
 import (
+	"bytes"
 	"encoding/pem"
 	"fmt"
+	"io/ioutil"
 	"log"
 	"net"
 	"os"
+	"path/filepath"
+	"strings"
 	"time"
 
 	"github.com/hashicorp/terraform/communicator/shared"
@@ -50,6 +54,8 @@ type connectionInfo struct {
 	BastionPrivateKey string `mapstructure:"bastion_private_key"`
 	BastionHost       string `mapstructure:"bastion_host"`
 	BastionPort       int    `mapstructure:"bastion_port"`
+
+	AgentIdentity string `mapstructure:"agent_identity"`
 }
 
 // parseConnectionInfo is used to convert the ConnInfo of the InstanceState into
@@ -186,7 +192,8 @@ type sshClientConfigOpts struct {
 
 func buildSSHClientConfig(opts sshClientConfigOpts) (*ssh.ClientConfig, error) {
 	conf := &ssh.ClientConfig{
-		User: opts.user,
+		HostKeyCallback: ssh.InsecureIgnoreHostKey(),
+		User:            opts.user,
 	}
 
 	if opts.privateKey != "" {
@@ -246,6 +253,7 @@ func connectToAgent(connInfo *connectionInfo) (*sshAgent, error) {
 	return &sshAgent{
 		agent: agent,
 		conn:  conn,
+		id:    connInfo.AgentIdentity,
 	}, nil
 
 }
@@ -255,6 +263,7 @@ func connectToAgent(connInfo *connectionInfo) (*sshAgent, error) {
 type sshAgent struct {
 	agent agent.Agent
 	conn  net.Conn
+	id    string
 }
 
 func (a *sshAgent) Close() error {
@@ -265,8 +274,127 @@ func (a *sshAgent) Close() error {
 	return a.conn.Close()
 }
 
+// make an attempt to either read the identity file or find a corresponding
+// public key file using the typical openssh naming convention.
+// This returns the public key in wire format, or nil when a key is not found.
+func findIDPublicKey(id string) []byte {
+	for _, d := range idKeyData(id) {
+		signer, err := ssh.ParsePrivateKey(d)
+		if err == nil {
+			log.Println("[DEBUG] parsed id private key")
+			pk := signer.PublicKey()
+			return pk.Marshal()
+		}
+
+		// try it as a publicKey
+		pk, err := ssh.ParsePublicKey(d)
+		if err == nil {
+			log.Println("[DEBUG] parsed id public key")
+			return pk.Marshal()
+		}
+
+		// finally try it as an authorized key
+		pk, _, _, _, err = ssh.ParseAuthorizedKey(d)
+		if err == nil {
+			log.Println("[DEBUG] parsed id authorized key")
+			return pk.Marshal()
+		}
+	}
+
+	return nil
+}
+
+// Try to read an id file using the id as the file path. Also read the .pub
+// file if it exists, as the id file may be encrypted. Return only the file
+// data read. We don't need to know what data came from which path, as we will
+// try parsing each as a private key, a public key and an authorized key
+// regardless.
+func idKeyData(id string) [][]byte {
+	idPath, err := filepath.Abs(id)
+	if err != nil {
+		return nil
+	}
+
+	var fileData [][]byte
+
+	paths := []string{idPath}
+
+	if !strings.HasSuffix(idPath, ".pub") {
+		paths = append(paths, idPath+".pub")
+	}
+
+	for _, p := range paths {
+		d, err := ioutil.ReadFile(p)
+		if err != nil {
+			log.Printf("[DEBUG] error reading %q: %s", p, err)
+			continue
+		}
+		log.Printf("[DEBUG] found identity data at %q", p)
+		fileData = append(fileData, d)
+	}
+
+	return fileData
+}
+
+// sortSigners moves a signer with an agent comment field matching the
+// agent_identity to the head of the list when attempting authentication. This
+// helps when there are more keys loaded in an agent than the host will allow
+// attempts.
+func (s *sshAgent) sortSigners(signers []ssh.Signer) {
+	if s.id == "" || len(signers) < 2 {
+		return
+	}
+
+	// if we can locate the public key, either by extracting it from the id or
+	// locating the .pub file, then we can more easily determine an exact match
+	idPk := findIDPublicKey(s.id)
+
+	// if we have a signer with a connect field that matches the id, send that
+	// first, otherwise put close matches at the front of the list.
+	head := 0
+	for i := range signers {
+		pk := signers[i].PublicKey()
+		k, ok := pk.(*agent.Key)
+		if !ok {
+			continue
+		}
+
+		// check for an exact match first
+		if bytes.Equal(pk.Marshal(), idPk) || s.id == k.Comment {
+			signers[0], signers[i] = signers[i], signers[0]
+			break
+		}
+
+		// no exact match yet, move it to the front if it's close. The agent
+		// may have loaded as a full filepath, while the config refers to it by
+		// filename only.
+		if strings.HasSuffix(k.Comment, s.id) {
+			signers[head], signers[i] = signers[i], signers[head]
+			head++
+			continue
+		}
+	}
+
+	ss := []string{}
+	for _, signer := range signers {
+		pk := signer.PublicKey()
+		k := pk.(*agent.Key)
+		ss = append(ss, k.Comment)
+	}
+}
+
+func (s *sshAgent) Signers() ([]ssh.Signer, error) {
+	signers, err := s.agent.Signers()
+	if err != nil {
+		return nil, err
+	}
+
+	s.sortSigners(signers)
+	return signers, nil
+}
+
 func (a *sshAgent) Auth() ssh.AuthMethod {
-	return ssh.PublicKeysCallback(a.agent.Signers)
+	return ssh.PublicKeysCallback(a.Signers)
 }
 
 func (a *sshAgent) ForwardToAgent(client *ssh.Client) error {
diff --git a/communicator/ssh/ssh_test.go b/communicator/ssh/ssh_test.go
new file mode 100644
index 000000000..9cd10a0a3
--- /dev/null
+++ b/communicator/ssh/ssh_test.go
@@ -0,0 +1,105 @@
+package ssh
+
+import (
+	"bytes"
+	"crypto/rand"
+	"crypto/rsa"
+	"crypto/x509"
+	"encoding/pem"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"testing"
+
+	"golang.org/x/crypto/ssh"
+)
+
+// verify that we can locate public key data
+func TestFindKeyData(t *testing.T) {
+	// setup a test directory
+	td, err := ioutil.TempDir("", "ssh")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer os.RemoveAll(td)
+	cwd, err := os.Getwd()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := os.Chdir(td); err != nil {
+		t.Fatal(err)
+	}
+	defer os.Chdir(cwd)
+
+	id := "provisioner_id"
+
+	pub := generateSSHKey(t, id)
+	pubData := pub.Marshal()
+
+	// backup the pub file, and replace it with a broken file to ensure we
+	// extract the public key from the private key.
+	if err := os.Rename(id+".pub", "saved.pub"); err != nil {
+		t.Fatal(err)
+	}
+	if err := ioutil.WriteFile(id+".pub", []byte("not a public key"), 0600); err != nil {
+		t.Fatal(err)
+	}
+
+	foundData := findIDPublicKey(id)
+	if !bytes.Equal(foundData, pubData) {
+		t.Fatalf("public key %q does not match", foundData)
+	}
+
+	// move the pub file back, and break the private key file to simulate an
+	// encrypted private key
+	if err := os.Rename("saved.pub", id+".pub"); err != nil {
+		t.Fatal(err)
+	}
+
+	if err := ioutil.WriteFile(id, []byte("encrypted private key"), 0600); err != nil {
+		t.Fatal(err)
+	}
+
+	foundData = findIDPublicKey(id)
+	if !bytes.Equal(foundData, pubData) {
+		t.Fatalf("public key %q does not match", foundData)
+	}
+
+	// check the file by path too
+	foundData = findIDPublicKey(filepath.Join(".", id))
+	if !bytes.Equal(foundData, pubData) {
+		t.Fatalf("public key %q does not match", foundData)
+	}
+}
+
+func generateSSHKey(t *testing.T, idFile string) ssh.PublicKey {
+	t.Helper()
+
+	priv, err := rsa.GenerateKey(rand.Reader, 2048)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	privFile, err := os.OpenFile(idFile, os.O_RDWR|os.O_CREATE, 0600)
+	defer privFile.Close()
+	if err != nil {
+		t.Fatal(err)
+	}
+	privPEM := &pem.Block{Type: "RSA PRIVATE KEY", Bytes: x509.MarshalPKCS1PrivateKey(priv)}
+	if err := pem.Encode(privFile, privPEM); err != nil {
+		t.Fatal(err)
+	}
+
+	// generate and write public key
+	pub, err := ssh.NewPublicKey(&priv.PublicKey)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	err = ioutil.WriteFile(idFile+".pub", ssh.MarshalAuthorizedKey(pub), 0600)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	return pub
+}
diff --git a/terraform/eval_validate.go b/terraform/eval_validate.go
index 478aa6400..e48af84ac 100644
--- a/terraform/eval_validate.go
+++ b/terraform/eval_validate.go
@@ -150,6 +150,7 @@ func (n *EvalValidateProvisioner) validateConnConfig(connConfig *ResourceConfig)
 		BastionUser       interface{} `mapstructure:"bastion_user"`
 		BastionPassword   interface{} `mapstructure:"bastion_password"`
 		BastionPrivateKey interface{} `mapstructure:"bastion_private_key"`
+		AgentIdentity     interface{} `mapstructure:"agent_identity"`
 
 		// For type=winrm only (enforced in winrm communicator)
 		HTTPS    interface{} `mapstructure:"https"`
diff --git a/vendor/golang.org/x/crypto/ssh/agent/client.go b/vendor/golang.org/x/crypto/ssh/agent/client.go
index ecfd7c58d..acb5ad80e 100644
--- a/vendor/golang.org/x/crypto/ssh/agent/client.go
+++ b/vendor/golang.org/x/crypto/ssh/agent/client.go
@@ -57,6 +57,17 @@ type Agent interface {
 	Signers() ([]ssh.Signer, error)
 }
 
+// ConstraintExtension describes an optional constraint defined by users.
+type ConstraintExtension struct {
+	// ExtensionName consist of a UTF-8 string suffixed by the
+	// implementation domain following the naming scheme defined
+	// in Section 4.2 of [RFC4251], e.g.  "foo@example.com".
+	ExtensionName string
+	// ExtensionDetails contains the actual content of the extended
+	// constraint.
+	ExtensionDetails []byte
+}
+
 // AddedKey describes an SSH key to be added to an Agent.
 type AddedKey struct {
 	// PrivateKey must be a *rsa.PrivateKey, *dsa.PrivateKey or
@@ -73,6 +84,9 @@ type AddedKey struct {
 	// ConfirmBeforeUse, if true, requests that the agent confirm with the
 	// user before each use of this key.
 	ConfirmBeforeUse bool
+	// ConstraintExtensions are the experimental or private-use constraints
+	// defined by users.
+	ConstraintExtensions []ConstraintExtension
 }
 
 // See [PROTOCOL.agent], section 3.
@@ -84,7 +98,7 @@ const (
 	agentAddIdentity         = 17
 	agentRemoveIdentity      = 18
 	agentRemoveAllIdentities = 19
-	agentAddIdConstrained    = 25
+	agentAddIDConstrained    = 25
 
 	// 3.3 Key-type independent requests from client to agent
 	agentAddSmartcardKey            = 20
@@ -94,8 +108,9 @@ const (
 	agentAddSmartcardKeyConstrained = 26
 
 	// 3.7 Key constraint identifiers
-	agentConstrainLifetime = 1
-	agentConstrainConfirm  = 2
+	agentConstrainLifetime  = 1
+	agentConstrainConfirm   = 2
+	agentConstrainExtension = 3
 )
 
 // maxAgentResponseBytes is the maximum agent reply size that is accepted. This
@@ -151,6 +166,19 @@ type publicKey struct {
 	Rest   []byte `ssh:"rest"`
 }
 
+// 3.7 Key constraint identifiers
+type constrainLifetimeAgentMsg struct {
+	LifetimeSecs uint32 `sshtype:"1"`
+}
+
+type constrainExtensionAgentMsg struct {
+	ExtensionName    string `sshtype:"3"`
+	ExtensionDetails []byte
+
+	// Rest is a field used for parsing, not part of message
+	Rest []byte `ssh:"rest"`
+}
+
 // Key represents a protocol 2 public key as defined in
 // [PROTOCOL.agent], section 2.5.2.
 type Key struct {
@@ -487,7 +515,7 @@ func (c *client) insertKey(s interface{}, comment string, constraints []byte) er
 
 	// if constraints are present then the message type needs to be changed.
 	if len(constraints) != 0 {
-		req[0] = agentAddIdConstrained
+		req[0] = agentAddIDConstrained
 	}
 
 	resp, err := c.call(req)
@@ -542,22 +570,18 @@ func (c *client) Add(key AddedKey) error {
 	var constraints []byte
 
 	if secs := key.LifetimeSecs; secs != 0 {
-		constraints = append(constraints, agentConstrainLifetime)
-
-		var secsBytes [4]byte
-		binary.BigEndian.PutUint32(secsBytes[:], secs)
-		constraints = append(constraints, secsBytes[:]...)
+		constraints = append(constraints, ssh.Marshal(constrainLifetimeAgentMsg{secs})...)
 	}
 
 	if key.ConfirmBeforeUse {
 		constraints = append(constraints, agentConstrainConfirm)
 	}
 
-	if cert := key.Certificate; cert == nil {
+	cert := key.Certificate
+	if cert == nil {
 		return c.insertKey(key.PrivateKey, key.Comment, constraints)
-	} else {
-		return c.insertCert(key.PrivateKey, cert, key.Comment, constraints)
 	}
+	return c.insertCert(key.PrivateKey, cert, key.Comment, constraints)
 }
 
 func (c *client) insertCert(s interface{}, cert *ssh.Certificate, comment string, constraints []byte) error {
@@ -609,7 +633,7 @@ func (c *client) insertCert(s interface{}, cert *ssh.Certificate, comment string
 
 	// if constraints are present then the message type needs to be changed.
 	if len(constraints) != 0 {
-		req[0] = agentAddIdConstrained
+		req[0] = agentAddIDConstrained
 	}
 
 	signer, err := ssh.NewSignerFromKey(s)
diff --git a/vendor/golang.org/x/crypto/ssh/agent/server.go b/vendor/golang.org/x/crypto/ssh/agent/server.go
index 68a333fa5..2e4692cbd 100644
--- a/vendor/golang.org/x/crypto/ssh/agent/server.go
+++ b/vendor/golang.org/x/crypto/ssh/agent/server.go
@@ -106,7 +106,7 @@ func (s *server) processRequest(data []byte) (interface{}, error) {
 		return nil, s.agent.Lock(req.Passphrase)
 
 	case agentUnlock:
-		var req agentLockMsg
+		var req agentUnlockMsg
 		if err := ssh.Unmarshal(data, &req); err != nil {
 			return nil, err
 		}
@@ -148,13 +148,51 @@ func (s *server) processRequest(data []byte) (interface{}, error) {
 		}
 		return rep, nil
 
-	case agentAddIdConstrained, agentAddIdentity:
+	case agentAddIDConstrained, agentAddIdentity:
 		return nil, s.insertIdentity(data)
 	}
 
 	return nil, fmt.Errorf("unknown opcode %d", data[0])
 }
 
+func parseConstraints(constraints []byte) (lifetimeSecs uint32, confirmBeforeUse bool, extensions []ConstraintExtension, err error) {
+	for len(constraints) != 0 {
+		switch constraints[0] {
+		case agentConstrainLifetime:
+			lifetimeSecs = binary.BigEndian.Uint32(constraints[1:5])
+			constraints = constraints[5:]
+		case agentConstrainConfirm:
+			confirmBeforeUse = true
+			constraints = constraints[1:]
+		case agentConstrainExtension:
+			var msg constrainExtensionAgentMsg
+			if err = ssh.Unmarshal(constraints, &msg); err != nil {
+				return 0, false, nil, err
+			}
+			extensions = append(extensions, ConstraintExtension{
+				ExtensionName:    msg.ExtensionName,
+				ExtensionDetails: msg.ExtensionDetails,
+			})
+			constraints = msg.Rest
+		default:
+			return 0, false, nil, fmt.Errorf("unknown constraint type: %d", constraints[0])
+		}
+	}
+	return
+}
+
+func setConstraints(key *AddedKey, constraintBytes []byte) error {
+	lifetimeSecs, confirmBeforeUse, constraintExtensions, err := parseConstraints(constraintBytes)
+	if err != nil {
+		return err
+	}
+
+	key.LifetimeSecs = lifetimeSecs
+	key.ConfirmBeforeUse = confirmBeforeUse
+	key.ConstraintExtensions = constraintExtensions
+	return nil
+}
+
 func parseRSAKey(req []byte) (*AddedKey, error) {
 	var k rsaKeyMsg
 	if err := ssh.Unmarshal(req, &k); err != nil {
@@ -173,7 +211,11 @@ func parseRSAKey(req []byte) (*AddedKey, error) {
 	}
 	priv.Precompute()
 
-	return &AddedKey{PrivateKey: priv, Comment: k.Comments}, nil
+	addedKey := &AddedKey{PrivateKey: priv, Comment: k.Comments}
+	if err := setConstraints(addedKey, k.Constraints); err != nil {
+		return nil, err
+	}
+	return addedKey, nil
 }
 
 func parseEd25519Key(req []byte) (*AddedKey, error) {
@@ -182,7 +224,12 @@ func parseEd25519Key(req []byte) (*AddedKey, error) {
 		return nil, err
 	}
 	priv := ed25519.PrivateKey(k.Priv)
-	return &AddedKey{PrivateKey: &priv, Comment: k.Comments}, nil
+
+	addedKey := &AddedKey{PrivateKey: &priv, Comment: k.Comments}
+	if err := setConstraints(addedKey, k.Constraints); err != nil {
+		return nil, err
+	}
+	return addedKey, nil
 }
 
 func parseDSAKey(req []byte) (*AddedKey, error) {
@@ -202,7 +249,11 @@ func parseDSAKey(req []byte) (*AddedKey, error) {
 		X: k.X,
 	}
 
-	return &AddedKey{PrivateKey: priv, Comment: k.Comments}, nil
+	addedKey := &AddedKey{PrivateKey: priv, Comment: k.Comments}
+	if err := setConstraints(addedKey, k.Constraints); err != nil {
+		return nil, err
+	}
+	return addedKey, nil
 }
 
 func unmarshalECDSA(curveName string, keyBytes []byte, privScalar *big.Int) (priv *ecdsa.PrivateKey, err error) {
@@ -243,7 +294,12 @@ func parseEd25519Cert(req []byte) (*AddedKey, error) {
 	if !ok {
 		return nil, errors.New("agent: bad ED25519 certificate")
 	}
-	return &AddedKey{PrivateKey: &priv, Certificate: cert, Comment: k.Comments}, nil
+
+	addedKey := &AddedKey{PrivateKey: &priv, Certificate: cert, Comment: k.Comments}
+	if err := setConstraints(addedKey, k.Constraints); err != nil {
+		return nil, err
+	}
+	return addedKey, nil
 }
 
 func parseECDSAKey(req []byte) (*AddedKey, error) {
@@ -257,7 +313,11 @@ func parseECDSAKey(req []byte) (*AddedKey, error) {
 		return nil, err
 	}
 
-	return &AddedKey{PrivateKey: priv, Comment: k.Comments}, nil
+	addedKey := &AddedKey{PrivateKey: priv, Comment: k.Comments}
+	if err := setConstraints(addedKey, k.Constraints); err != nil {
+		return nil, err
+	}
+	return addedKey, nil
 }
 
 func parseRSACert(req []byte) (*AddedKey, error) {
@@ -300,7 +360,11 @@ func parseRSACert(req []byte) (*AddedKey, error) {
 	}
 	priv.Precompute()
 
-	return &AddedKey{PrivateKey: &priv, Certificate: cert, Comment: k.Comments}, nil
+	addedKey := &AddedKey{PrivateKey: &priv, Certificate: cert, Comment: k.Comments}
+	if err := setConstraints(addedKey, k.Constraints); err != nil {
+		return nil, err
+	}
+	return addedKey, nil
 }
 
 func parseDSACert(req []byte) (*AddedKey, error) {
@@ -338,7 +402,11 @@ func parseDSACert(req []byte) (*AddedKey, error) {
 		X: k.X,
 	}
 
-	return &AddedKey{PrivateKey: priv, Certificate: cert, Comment: k.Comments}, nil
+	addedKey := &AddedKey{PrivateKey: priv, Certificate: cert, Comment: k.Comments}
+	if err := setConstraints(addedKey, k.Constraints); err != nil {
+		return nil, err
+	}
+	return addedKey, nil
 }
 
 func parseECDSACert(req []byte) (*AddedKey, error) {
@@ -371,7 +439,11 @@ func parseECDSACert(req []byte) (*AddedKey, error) {
 		return nil, err
 	}
 
-	return &AddedKey{PrivateKey: priv, Certificate: cert, Comment: k.Comments}, nil
+	addedKey := &AddedKey{PrivateKey: priv, Certificate: cert, Comment: k.Comments}
+	if err := setConstraints(addedKey, k.Constraints); err != nil {
+		return nil, err
+	}
+	return addedKey, nil
 }
 
 func (s *server) insertIdentity(req []byte) error {
diff --git a/vendor/golang.org/x/crypto/ssh/buffer.go b/vendor/golang.org/x/crypto/ssh/buffer.go
index 6931b5114..1ab07d078 100644
--- a/vendor/golang.org/x/crypto/ssh/buffer.go
+++ b/vendor/golang.org/x/crypto/ssh/buffer.go
@@ -51,13 +51,12 @@ func (b *buffer) write(buf []byte) {
 }
 
 // eof closes the buffer. Reads from the buffer once all
-// the data has been consumed will receive os.EOF.
-func (b *buffer) eof() error {
+// the data has been consumed will receive io.EOF.
+func (b *buffer) eof() {
 	b.Cond.L.Lock()
 	b.closed = true
 	b.Cond.Signal()
 	b.Cond.L.Unlock()
-	return nil
 }
 
 // Read reads data from the internal buffer in buf.  Reads will block
diff --git a/vendor/golang.org/x/crypto/ssh/certs.go b/vendor/golang.org/x/crypto/ssh/certs.go
index 6331c94d5..5c9fadcee 100644
--- a/vendor/golang.org/x/crypto/ssh/certs.go
+++ b/vendor/golang.org/x/crypto/ssh/certs.go
@@ -251,10 +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.
@@ -268,7 +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
@@ -290,8 +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
@@ -308,6 +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
@@ -323,7 +343,7 @@ func (c *CertChecker) CheckCert(principal string, cert *Certificate) error {
 		return fmt.Errorf("ssh: certicate serial %d revoked", cert.Serial)
 	}
 
-	for opt, _ := range cert.CriticalOptions {
+	for opt := range cert.CriticalOptions {
 		// sourceAddressCriticalOption will be enforced by
 		// serverAuthenticate
 		if opt == sourceAddressCriticalOption {
@@ -356,10 +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
diff --git a/vendor/golang.org/x/crypto/ssh/channel.go b/vendor/golang.org/x/crypto/ssh/channel.go
index 195530ea0..c0834c00d 100644
--- a/vendor/golang.org/x/crypto/ssh/channel.go
+++ b/vendor/golang.org/x/crypto/ssh/channel.go
@@ -205,32 +205,32 @@ type channel struct {
 
 // writePacket sends a packet. If the packet is a channel close, it updates
 // sentClose. This method takes the lock c.writeMu.
-func (c *channel) writePacket(packet []byte) error {
-	c.writeMu.Lock()
-	if c.sentClose {
-		c.writeMu.Unlock()
+func (ch *channel) writePacket(packet []byte) error {
+	ch.writeMu.Lock()
+	if ch.sentClose {
+		ch.writeMu.Unlock()
 		return io.EOF
 	}
-	c.sentClose = (packet[0] == msgChannelClose)
-	err := c.mux.conn.writePacket(packet)
-	c.writeMu.Unlock()
+	ch.sentClose = (packet[0] == msgChannelClose)
+	err := ch.mux.conn.writePacket(packet)
+	ch.writeMu.Unlock()
 	return err
 }
 
-func (c *channel) sendMessage(msg interface{}) error {
+func (ch *channel) sendMessage(msg interface{}) error {
 	if debugMux {
-		log.Printf("send(%d): %#v", c.mux.chanList.offset, msg)
+		log.Printf("send(%d): %#v", ch.mux.chanList.offset, msg)
 	}
 
 	p := Marshal(msg)
-	binary.BigEndian.PutUint32(p[1:], c.remoteId)
-	return c.writePacket(p)
+	binary.BigEndian.PutUint32(p[1:], ch.remoteId)
+	return ch.writePacket(p)
 }
 
 // WriteExtended writes data to a specific extended stream. These streams are
 // used, for example, for stderr.
-func (c *channel) WriteExtended(data []byte, extendedCode uint32) (n int, err error) {
-	if c.sentEOF {
+func (ch *channel) WriteExtended(data []byte, extendedCode uint32) (n int, err error) {
+	if ch.sentEOF {
 		return 0, io.EOF
 	}
 	// 1 byte message type, 4 bytes remoteId, 4 bytes data length
@@ -241,16 +241,16 @@ func (c *channel) WriteExtended(data []byte, extendedCode uint32) (n int, err er
 		opCode = msgChannelExtendedData
 	}
 
-	c.writeMu.Lock()
-	packet := c.packetPool[extendedCode]
+	ch.writeMu.Lock()
+	packet := ch.packetPool[extendedCode]
 	// We don't remove the buffer from packetPool, so
 	// WriteExtended calls from different goroutines will be
 	// flagged as errors by the race detector.
-	c.writeMu.Unlock()
+	ch.writeMu.Unlock()
 
 	for len(data) > 0 {
-		space := min(c.maxRemotePayload, len(data))
-		if space, err = c.remoteWin.reserve(space); err != nil {
+		space := min(ch.maxRemotePayload, len(data))
+		if space, err = ch.remoteWin.reserve(space); err != nil {
 			return n, err
 		}
 		if want := headerLength + space; uint32(cap(packet)) < want {
@@ -262,13 +262,13 @@ func (c *channel) WriteExtended(data []byte, extendedCode uint32) (n int, err er
 		todo := data[:space]
 
 		packet[0] = opCode
-		binary.BigEndian.PutUint32(packet[1:], c.remoteId)
+		binary.BigEndian.PutUint32(packet[1:], ch.remoteId)
 		if extendedCode > 0 {
 			binary.BigEndian.PutUint32(packet[5:], uint32(extendedCode))
 		}
 		binary.BigEndian.PutUint32(packet[headerLength-4:], uint32(len(todo)))
 		copy(packet[headerLength:], todo)
-		if err = c.writePacket(packet); err != nil {
+		if err = ch.writePacket(packet); err != nil {
 			return n, err
 		}
 
@@ -276,14 +276,14 @@ func (c *channel) WriteExtended(data []byte, extendedCode uint32) (n int, err er
 		data = data[len(todo):]
 	}
 
-	c.writeMu.Lock()
-	c.packetPool[extendedCode] = packet
-	c.writeMu.Unlock()
+	ch.writeMu.Lock()
+	ch.packetPool[extendedCode] = packet
+	ch.writeMu.Unlock()
 
 	return n, err
 }
 
-func (c *channel) handleData(packet []byte) error {
+func (ch *channel) handleData(packet []byte) error {
 	headerLen := 9
 	isExtendedData := packet[0] == msgChannelExtendedData
 	if isExtendedData {
@@ -303,7 +303,7 @@ func (c *channel) handleData(packet []byte) error {
 	if length == 0 {
 		return nil
 	}
-	if length > c.maxIncomingPayload {
+	if length > ch.maxIncomingPayload {
 		// TODO(hanwen): should send Disconnect?
 		return errors.New("ssh: incoming packet exceeds maximum payload size")
 	}
@@ -313,21 +313,21 @@ func (c *channel) handleData(packet []byte) error {
 		return errors.New("ssh: wrong packet length")
 	}
 
-	c.windowMu.Lock()
-	if c.myWindow < length {
-		c.windowMu.Unlock()
+	ch.windowMu.Lock()
+	if ch.myWindow < length {
+		ch.windowMu.Unlock()
 		// TODO(hanwen): should send Disconnect with reason?
 		return errors.New("ssh: remote side wrote too much")
 	}
-	c.myWindow -= length
-	c.windowMu.Unlock()
+	ch.myWindow -= length
+	ch.windowMu.Unlock()
 
 	if extended == 1 {
-		c.extPending.write(data)
+		ch.extPending.write(data)
 	} else if extended > 0 {
 		// discard other extended data.
 	} else {
-		c.pending.write(data)
+		ch.pending.write(data)
 	}
 	return nil
 }
@@ -384,31 +384,31 @@ func (c *channel) close() {
 // responseMessageReceived is called when a success or failure message is
 // received on a channel to check that such a message is reasonable for the
 // given channel.
-func (c *channel) responseMessageReceived() error {
-	if c.direction == channelInbound {
+func (ch *channel) responseMessageReceived() error {
+	if ch.direction == channelInbound {
 		return errors.New("ssh: channel response message received on inbound channel")
 	}
-	if c.decided {
+	if ch.decided {
 		return errors.New("ssh: duplicate response received for channel")
 	}
-	c.decided = true
+	ch.decided = true
 	return nil
 }
 
-func (c *channel) handlePacket(packet []byte) error {
+func (ch *channel) handlePacket(packet []byte) error {
 	switch packet[0] {
 	case msgChannelData, msgChannelExtendedData:
-		return c.handleData(packet)
+		return ch.handleData(packet)
 	case msgChannelClose:
-		c.sendMessage(channelCloseMsg{PeersId: c.remoteId})
-		c.mux.chanList.remove(c.localId)
-		c.close()
+		ch.sendMessage(channelCloseMsg{PeersID: ch.remoteId})
+		ch.mux.chanList.remove(ch.localId)
+		ch.close()
 		return nil
 	case msgChannelEOF:
 		// RFC 4254 is mute on how EOF affects dataExt messages but
 		// it is logical to signal EOF at the same time.
-		c.extPending.eof()
-		c.pending.eof()
+		ch.extPending.eof()
+		ch.pending.eof()
 		return nil
 	}
 
@@ -419,24 +419,24 @@ func (c *channel) handlePacket(packet []byte) error {
 
 	switch msg := decoded.(type) {
 	case *channelOpenFailureMsg:
-		if err := c.responseMessageReceived(); err != nil {
+		if err := ch.responseMessageReceived(); err != nil {
 			return err
 		}
-		c.mux.chanList.remove(msg.PeersId)
-		c.msg <- msg
+		ch.mux.chanList.remove(msg.PeersID)
+		ch.msg <- msg
 	case *channelOpenConfirmMsg:
-		if err := c.responseMessageReceived(); err != nil {
+		if err := ch.responseMessageReceived(); err != nil {
 			return err
 		}
 		if msg.MaxPacketSize < minPacketLength || msg.MaxPacketSize > 1<<31 {
 			return fmt.Errorf("ssh: invalid MaxPacketSize %d from peer", msg.MaxPacketSize)
 		}
-		c.remoteId = msg.MyId
-		c.maxRemotePayload = msg.MaxPacketSize
-		c.remoteWin.add(msg.MyWindow)
-		c.msg <- msg
+		ch.remoteId = msg.MyID
+		ch.maxRemotePayload = msg.MaxPacketSize
+		ch.remoteWin.add(msg.MyWindow)
+		ch.msg <- msg
 	case *windowAdjustMsg:
-		if !c.remoteWin.add(msg.AdditionalBytes) {
+		if !ch.remoteWin.add(msg.AdditionalBytes) {
 			return fmt.Errorf("ssh: invalid window update for %d bytes", msg.AdditionalBytes)
 		}
 	case *channelRequestMsg:
@@ -444,12 +444,12 @@ func (c *channel) handlePacket(packet []byte) error {
 			Type:      msg.Request,
 			WantReply: msg.WantReply,
 			Payload:   msg.RequestSpecificData,
-			ch:        c,
+			ch:        ch,
 		}
 
-		c.incomingRequests <- &req
+		ch.incomingRequests <- &req
 	default:
-		c.msg <- msg
+		ch.msg <- msg
 	}
 	return nil
 }
@@ -488,23 +488,23 @@ func (e *extChannel) Read(data []byte) (n int, err error) {
 	return e.ch.ReadExtended(data, e.code)
 }
 
-func (c *channel) Accept() (Channel, <-chan *Request, error) {
-	if c.decided {
+func (ch *channel) Accept() (Channel, <-chan *Request, error) {
+	if ch.decided {
 		return nil, nil, errDecidedAlready
 	}
-	c.maxIncomingPayload = channelMaxPacket
+	ch.maxIncomingPayload = channelMaxPacket
 	confirm := channelOpenConfirmMsg{
-		PeersId:       c.remoteId,
-		MyId:          c.localId,
-		MyWindow:      c.myWindow,
-		MaxPacketSize: c.maxIncomingPayload,
+		PeersID:       ch.remoteId,
+		MyID:          ch.localId,
+		MyWindow:      ch.myWindow,
+		MaxPacketSize: ch.maxIncomingPayload,
 	}
-	c.decided = true
-	if err := c.sendMessage(confirm); err != nil {
+	ch.decided = true
+	if err := ch.sendMessage(confirm); err != nil {
 		return nil, nil, err
 	}
 
-	return c, c.incomingRequests, nil
+	return ch, ch.incomingRequests, nil
 }
 
 func (ch *channel) Reject(reason RejectionReason, message string) error {
@@ -512,7 +512,7 @@ func (ch *channel) Reject(reason RejectionReason, message string) error {
 		return errDecidedAlready
 	}
 	reject := channelOpenFailureMsg{
-		PeersId:  ch.remoteId,
+		PeersID:  ch.remoteId,
 		Reason:   reason,
 		Message:  message,
 		Language: "en",
@@ -541,7 +541,7 @@ func (ch *channel) CloseWrite() error {
 	}
 	ch.sentEOF = true
 	return ch.sendMessage(channelEOFMsg{
-		PeersId: ch.remoteId})
+		PeersID: ch.remoteId})
 }
 
 func (ch *channel) Close() error {
@@ -550,7 +550,7 @@ func (ch *channel) Close() error {
 	}
 
 	return ch.sendMessage(channelCloseMsg{
-		PeersId: ch.remoteId})
+		PeersID: ch.remoteId})
 }
 
 // Extended returns an io.ReadWriter that sends and receives data on the given,
@@ -577,7 +577,7 @@ func (ch *channel) SendRequest(name string, wantReply bool, payload []byte) (boo
 	}
 
 	msg := channelRequestMsg{
-		PeersId:             ch.remoteId,
+		PeersID:             ch.remoteId,
 		Request:             name,
 		WantReply:           wantReply,
 		RequestSpecificData: payload,
@@ -614,11 +614,11 @@ func (ch *channel) ackRequest(ok bool) error {
 	var msg interface{}
 	if !ok {
 		msg = channelRequestFailureMsg{
-			PeersId: ch.remoteId,
+			PeersID: ch.remoteId,
 		}
 	} else {
 		msg = channelRequestSuccessMsg{
-			PeersId: ch.remoteId,
+			PeersID: ch.remoteId,
 		}
 	}
 	return ch.sendMessage(msg)
diff --git a/vendor/golang.org/x/crypto/ssh/cipher.go b/vendor/golang.org/x/crypto/ssh/cipher.go
index 13484ab4b..e67c5e0aa 100644
--- a/vendor/golang.org/x/crypto/ssh/cipher.go
+++ b/vendor/golang.org/x/crypto/ssh/cipher.go
@@ -304,7 +304,7 @@ type gcmCipher struct {
 	buf    []byte
 }
 
-func newGCMCipher(iv, key, macKey []byte) (packetCipher, error) {
+func newGCMCipher(iv, key []byte) (packetCipher, error) {
 	c, err := aes.NewCipher(key)
 	if err != nil {
 		return nil, err
@@ -372,7 +372,7 @@ func (c *gcmCipher) readPacket(seqNum uint32, r io.Reader) ([]byte, error) {
 	}
 	length := binary.BigEndian.Uint32(c.prefix[:])
 	if length > maxPacket {
-		return nil, errors.New("ssh: max packet length exceeded.")
+		return nil, errors.New("ssh: max packet length exceeded")
 	}
 
 	if cap(c.buf) < int(length+gcmTagSize) {
@@ -392,7 +392,9 @@ func (c *gcmCipher) readPacket(seqNum uint32, r io.Reader) ([]byte, error) {
 	c.incIV()
 
 	padding := plain[0]
-	if padding < 4 || padding >= 20 {
+	if padding < 4 {
+		// padding is a byte, so it automatically satisfies
+		// the maximum size, which is 255.
 		return nil, fmt.Errorf("ssh: illegal padding %d", padding)
 	}
 
@@ -546,11 +548,11 @@ func (c *cbcCipher) readPacketLeaky(seqNum uint32, r io.Reader) ([]byte, error)
 		c.packetData = c.packetData[:entirePacketSize]
 	}
 
-	if n, err := io.ReadFull(r, c.packetData[firstBlockLength:]); err != nil {
+	n, err := io.ReadFull(r, c.packetData[firstBlockLength:])
+	if err != nil {
 		return nil, err
-	} else {
-		c.oracleCamouflage -= uint32(n)
 	}
+	c.oracleCamouflage -= uint32(n)
 
 	remainingCrypted := c.packetData[firstBlockLength:macStart]
 	c.decrypter.CryptBlocks(remainingCrypted, remainingCrypted)
diff --git a/vendor/golang.org/x/crypto/ssh/client.go b/vendor/golang.org/x/crypto/ssh/client.go
index c97f2978e..6fd199455 100644
--- a/vendor/golang.org/x/crypto/ssh/client.go
+++ b/vendor/golang.org/x/crypto/ssh/client.go
@@ -5,15 +5,17 @@
 package ssh
 
 import (
+	"bytes"
 	"errors"
 	"fmt"
 	"net"
+	"os"
 	"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
 
@@ -59,6 +61,7 @@ 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
 }
 
@@ -68,6 +71,11 @@ 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},
 	}
@@ -173,6 +181,17 @@ 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
+
+// BannerCallback is the function type used for treat the banner sent by
+// the server. A BannerCallback receives the message sent by the remote server.
+type BannerCallback func(message string) 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 {
@@ -188,10 +207,18 @@ 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
+
+	// BannerCallback is called during the SSH dance to display a custom
+	// server's message. The client configuration can supply this callback to
+	// handle it as wished. The function BannerDisplayStderr can be used for
+	// simplistic display on Stderr.
+	BannerCallback BannerCallback
 
 	// ClientVersion contains the version identification string that will
 	// be used for the connection. If empty, a reasonable default is used.
@@ -209,3 +236,43 @@ type ClientConfig struct {
 	// 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
+}
+
+// BannerDisplayStderr returns a function that can be used for
+// ClientConfig.BannerCallback to display banners on os.Stderr.
+func BannerDisplayStderr() BannerCallback {
+	return func(banner string) error {
+		_, err := os.Stderr.WriteString(banner)
+
+		return err
+	}
+}
diff --git a/vendor/golang.org/x/crypto/ssh/client_auth.go b/vendor/golang.org/x/crypto/ssh/client_auth.go
index fd1ec5dda..a1252cb9b 100644
--- a/vendor/golang.org/x/crypto/ssh/client_auth.go
+++ b/vendor/golang.org/x/crypto/ssh/client_auth.go
@@ -179,31 +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,
@@ -236,13 +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()
@@ -272,7 +283,9 @@ func confirmKeyAck(key PublicKey, c packetConn) (bool, error) {
 		}
 		switch packet[0] {
 		case msgUserAuthBanner:
-			// TODO(gpaul): add callback to present the banner to the user
+			if err := handleBannerResponse(c, packet); err != nil {
+				return false, err
+			}
 		case msgUserAuthPubKeyOk:
 			var msg userAuthPubKeyOkMsg
 			if err := Unmarshal(packet, &msg); err != nil {
@@ -314,7 +327,9 @@ func handleAuthResponse(c packetConn) (bool, []string, error) {
 
 		switch packet[0] {
 		case msgUserAuthBanner:
-			// TODO: add callback to present the banner to the user
+			if err := handleBannerResponse(c, packet); err != nil {
+				return false, nil, err
+			}
 		case msgUserAuthFailure:
 			var msg userAuthFailureMsg
 			if err := Unmarshal(packet, &msg); err != nil {
@@ -329,6 +344,24 @@ func handleAuthResponse(c packetConn) (bool, []string, error) {
 	}
 }
 
+func handleBannerResponse(c packetConn, packet []byte) error {
+	var msg userAuthBannerMsg
+	if err := Unmarshal(packet, &msg); err != nil {
+		return err
+	}
+
+	transport, ok := c.(*handshakeTransport)
+	if !ok {
+		return nil
+	}
+
+	if transport.bannerCallback != nil {
+		return transport.bannerCallback(msg.Message)
+	}
+
+	return nil
+}
+
 // KeyboardInteractiveChallenge should print questions, optionally
 // disabling echoing (e.g. for passwords), and return all the answers.
 // Challenge may be called multiple times in a single session. After
@@ -338,7 +371,7 @@ func handleAuthResponse(c packetConn) (bool, []string, error) {
 // both CLI and GUI environments.
 type KeyboardInteractiveChallenge func(user, instruction string, questions []string, echos []bool) (answers []string, err error)
 
-// KeyboardInteractive returns a AuthMethod using a prompt/response
+// KeyboardInteractive returns an AuthMethod using a prompt/response
 // sequence controlled by the server.
 func KeyboardInteractive(challenge KeyboardInteractiveChallenge) AuthMethod {
 	return challenge
@@ -374,7 +407,9 @@ func (cb KeyboardInteractiveChallenge) auth(session []byte, user string, c packe
 		// like handleAuthResponse, but with less options.
 		switch packet[0] {
 		case msgUserAuthBanner:
-			// TODO: Print banners during userauth.
+			if err := handleBannerResponse(c, packet); err != nil {
+				return false, nil, err
+			}
 			continue
 		case msgUserAuthInfoRequest:
 			// OK
diff --git a/vendor/golang.org/x/crypto/ssh/common.go b/vendor/golang.org/x/crypto/ssh/common.go
index 8656d0f85..135b4edd7 100644
--- a/vendor/golang.org/x/crypto/ssh/common.go
+++ b/vendor/golang.org/x/crypto/ssh/common.go
@@ -9,6 +9,7 @@ import (
 	"crypto/rand"
 	"fmt"
 	"io"
+	"math"
 	"sync"
 
 	_ "crypto/sha1"
@@ -40,7 +41,7 @@ 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,
@@ -186,7 +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
@@ -230,17 +231,18 @@ 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
 	}
 }
 
 // buildDataSignedForAuth returns the data that is signed in order to prove
 // possession of a private key. See RFC 4252, section 7.
-func buildDataSignedForAuth(sessionId []byte, req userAuthRequestMsg, algo, pubKey []byte) []byte {
+func buildDataSignedForAuth(sessionID []byte, req userAuthRequestMsg, algo, pubKey []byte) []byte {
 	data := struct {
 		Session []byte
 		Type    byte
@@ -251,7 +253,7 @@ func buildDataSignedForAuth(sessionId []byte, req userAuthRequestMsg, algo, pubK
 		Algo    []byte
 		PubKey  []byte
 	}{
-		sessionId,
+		sessionID,
 		msgUserAuthRequest,
 		req.User,
 		req.Service,
diff --git a/vendor/golang.org/x/crypto/ssh/connection.go b/vendor/golang.org/x/crypto/ssh/connection.go
index e786f2f9a..fd6b0681b 100644
--- a/vendor/golang.org/x/crypto/ssh/connection.go
+++ b/vendor/golang.org/x/crypto/ssh/connection.go
@@ -25,7 +25,7 @@ type ConnMetadata interface {
 	// User returns the user ID for this connection.
 	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
diff --git a/vendor/golang.org/x/crypto/ssh/doc.go b/vendor/golang.org/x/crypto/ssh/doc.go
index d6be89466..67b7322c0 100644
--- a/vendor/golang.org/x/crypto/ssh/doc.go
+++ b/vendor/golang.org/x/crypto/ssh/doc.go
@@ -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 // import "golang.org/x/crypto/ssh"
diff --git a/vendor/golang.org/x/crypto/ssh/handshake.go b/vendor/golang.org/x/crypto/ssh/handshake.go
index 8de650644..4f7912ecd 100644
--- a/vendor/golang.org/x/crypto/ssh/handshake.go
+++ b/vendor/golang.org/x/crypto/ssh/handshake.go
@@ -74,10 +74,15 @@ type handshakeTransport struct {
 	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
 
+	// bannerCallback is non-empty if we are the client and it has been set in
+	// ClientConfig. In that case it is called during the user authentication
+	// dance to handle a custom server's message.
+	bannerCallback BannerCallback
+
 	// Algorithms agreed in the last key exchange.
 	algorithms *algorithms
 
@@ -107,6 +112,8 @@ func newHandshakeTransport(conn keyingTransport, config *Config, clientVersion,
 
 		config: config,
 	}
+	t.resetReadThresholds()
+	t.resetWriteThresholds()
 
 	// We always start with a mandatory key exchange.
 	t.requestKex <- struct{}{}
@@ -118,6 +125,7 @@ func newClientTransport(conn keyingTransport, clientVersion, serverVersion []byt
 	t.dialAddress = dialAddr
 	t.remoteAddr = addr
 	t.hostKeyCallback = config.HostKeyCallback
+	t.bannerCallback = config.BannerCallback
 	if config.HostKeyAlgorithms != nil {
 		t.hostKeyAlgorithms = config.HostKeyAlgorithms
 	} else {
@@ -237,6 +245,17 @@ func (t *handshakeTransport) requestKeyExchange() {
 	}
 }
 
+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:
@@ -285,12 +304,8 @@ write:
 		t.writeError = err
 		t.sentInitPacket = nil
 		t.sentInitMsg = nil
-		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()
-		}
+
+		t.resetWriteThresholds()
 
 		// we have completed the key exchange. Since the
 		// reader is still blocked, it is safe to clear out
@@ -344,6 +359,17 @@ write:
 // 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 {
@@ -391,12 +417,7 @@ func (t *handshakeTransport) readOnePacket(first bool) ([]byte, error) {
 		return nil, err
 	}
 
-	t.readPacketsLeft = packetRekeyThreshold
-	if t.config.RekeyThreshold > 0 {
-		t.readBytesLeft = int64(t.config.RekeyThreshold)
-	} else {
-		t.readBytesLeft = t.algorithms.r.rekeyBytes()
-	}
+	t.resetReadThresholds()
 
 	// By default, a key exchange is hidden from higher layers by
 	// translating it into msgIgnore.
@@ -574,7 +595,9 @@ func (t *handshakeTransport) enterKeyExchange(otherInitPacket []byte) error {
 	}
 	result.SessionID = t.sessionID
 
-	t.conn.prepareKeyChange(t.algorithms, result)
+	if err := t.conn.prepareKeyChange(t.algorithms, result); err != nil {
+		return err
+	}
 	if err = t.conn.writePacket([]byte{msgNewKeys}); err != nil {
 		return err
 	}
@@ -614,11 +637,9 @@ 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
diff --git a/vendor/golang.org/x/crypto/ssh/kex.go b/vendor/golang.org/x/crypto/ssh/kex.go
index c87fbebfd..f34bcc013 100644
--- a/vendor/golang.org/x/crypto/ssh/kex.go
+++ b/vendor/golang.org/x/crypto/ssh/kex.go
@@ -119,7 +119,7 @@ func (group *dhGroup) Client(c packetConn, randSource io.Reader, magics *handsha
 		return nil, err
 	}
 
-	kInt, err := group.diffieHellman(kexDHReply.Y, x)
+	ki, err := group.diffieHellman(kexDHReply.Y, x)
 	if err != nil {
 		return nil, err
 	}
@@ -129,8 +129,8 @@ func (group *dhGroup) Client(c packetConn, randSource io.Reader, magics *handsha
 	writeString(h, kexDHReply.HostKey)
 	writeInt(h, X)
 	writeInt(h, kexDHReply.Y)
-	K := make([]byte, intLength(kInt))
-	marshalInt(K, kInt)
+	K := make([]byte, intLength(ki))
+	marshalInt(K, ki)
 	h.Write(K)
 
 	return &kexResult{
@@ -164,7 +164,7 @@ func (group *dhGroup) Server(c packetConn, randSource io.Reader, magics *handsha
 	}
 
 	Y := new(big.Int).Exp(group.g, y, group.p)
-	kInt, err := group.diffieHellman(kexDHInit.X, y)
+	ki, err := group.diffieHellman(kexDHInit.X, y)
 	if err != nil {
 		return nil, err
 	}
@@ -177,8 +177,8 @@ func (group *dhGroup) Server(c packetConn, randSource io.Reader, magics *handsha
 	writeInt(h, kexDHInit.X)
 	writeInt(h, Y)
 
-	K := make([]byte, intLength(kInt))
-	marshalInt(K, kInt)
+	K := make([]byte, intLength(ki))
+	marshalInt(K, ki)
 	h.Write(K)
 
 	H := h.Sum(nil)
@@ -383,8 +383,8 @@ 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),
 	}
 
@@ -393,8 +393,8 @@ 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),
 	}
 
@@ -462,9 +462,9 @@ func (kex *curve25519sha256) Client(c packetConn, rand io.Reader, magics *handsh
 	writeString(h, kp.pub[:])
 	writeString(h, reply.EphemeralPubKey)
 
-	kInt := new(big.Int).SetBytes(secret[:])
-	K := make([]byte, intLength(kInt))
-	marshalInt(K, kInt)
+	ki := new(big.Int).SetBytes(secret[:])
+	K := make([]byte, intLength(ki))
+	marshalInt(K, ki)
 	h.Write(K)
 
 	return &kexResult{
@@ -510,9 +510,9 @@ func (kex *curve25519sha256) Server(c packetConn, rand io.Reader, magics *handsh
 	writeString(h, kexInit.ClientPubKey)
 	writeString(h, kp.pub[:])
 
-	kInt := new(big.Int).SetBytes(secret[:])
-	K := make([]byte, intLength(kInt))
-	marshalInt(K, kInt)
+	ki := new(big.Int).SetBytes(secret[:])
+	K := make([]byte, intLength(ki))
+	marshalInt(K, ki)
 	h.Write(K)
 
 	H := h.Sum(nil)
diff --git a/vendor/golang.org/x/crypto/ssh/keys.go b/vendor/golang.org/x/crypto/ssh/keys.go
index f38de9898..dadf41ab7 100644
--- a/vendor/golang.org/x/crypto/ssh/keys.go
+++ b/vendor/golang.org/x/crypto/ssh/keys.go
@@ -363,10 +363,21 @@ func (r *rsaPublicKey) CryptoPublicKey() crypto.PublicKey {
 
 type dsaPublicKey dsa.PublicKey
 
-func (r *dsaPublicKey) Type() string {
+func (k *dsaPublicKey) Type() string {
 	return "ssh-dss"
 }
 
+func checkDSAParams(param *dsa.Parameters) error {
+	// SSH specifies FIPS 186-2, which only provided a single size
+	// (1024 bits) DSA key. FIPS 186-3 allows for larger key
+	// sizes, which would confuse SSH.
+	if l := param.P.BitLen(); l != 1024 {
+		return fmt.Errorf("ssh: unsupported DSA key size %d", l)
+	}
+
+	return nil
+}
+
 // parseDSA parses an DSA key according to RFC 4253, section 6.6.
 func parseDSA(in []byte) (out PublicKey, rest []byte, err error) {
 	var w struct {
@@ -377,13 +388,18 @@ func parseDSA(in []byte) (out PublicKey, rest []byte, err error) {
 		return nil, nil, err
 	}
 
+	param := dsa.Parameters{
+		P: w.P,
+		Q: w.Q,
+		G: w.G,
+	}
+	if err := checkDSAParams(&param); err != nil {
+		return nil, nil, err
+	}
+
 	key := &dsaPublicKey{
-		Parameters: dsa.Parameters{
-			P: w.P,
-			Q: w.Q,
-			G: w.G,
-		},
-		Y: w.Y,
+		Parameters: param,
+		Y:          w.Y,
 	}
 	return key, w.Rest, nil
 }
@@ -465,12 +481,12 @@ func (k *dsaPrivateKey) Sign(rand io.Reader, data []byte) (*Signature, error) {
 
 type ecdsaPublicKey ecdsa.PublicKey
 
-func (key *ecdsaPublicKey) Type() string {
-	return "ecdsa-sha2-" + key.nistID()
+func (k *ecdsaPublicKey) Type() string {
+	return "ecdsa-sha2-" + k.nistID()
 }
 
-func (key *ecdsaPublicKey) nistID() string {
-	switch key.Params().BitSize {
+func (k *ecdsaPublicKey) nistID() string {
+	switch k.Params().BitSize {
 	case 256:
 		return "nistp256"
 	case 384:
@@ -483,7 +499,7 @@ func (key *ecdsaPublicKey) nistID() string {
 
 type ed25519PublicKey ed25519.PublicKey
 
-func (key ed25519PublicKey) Type() string {
+func (k ed25519PublicKey) Type() string {
 	return KeyAlgoED25519
 }
 
@@ -502,23 +518,23 @@ func parseED25519(in []byte) (out PublicKey, rest []byte, err error) {
 	return (ed25519PublicKey)(key), w.Rest, nil
 }
 
-func (key ed25519PublicKey) Marshal() []byte {
+func (k ed25519PublicKey) Marshal() []byte {
 	w := struct {
 		Name     string
 		KeyBytes []byte
 	}{
 		KeyAlgoED25519,
-		[]byte(key),
+		[]byte(k),
 	}
 	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())
+func (k ed25519PublicKey) Verify(b []byte, sig *Signature) error {
+	if sig.Format != k.Type() {
+		return fmt.Errorf("ssh: signature type %s for key type %s", sig.Format, k.Type())
 	}
 
-	edKey := (ed25519.PublicKey)(key)
+	edKey := (ed25519.PublicKey)(k)
 	if ok := ed25519.Verify(edKey, b, sig.Blob); !ok {
 		return errors.New("ssh: signature did not verify")
 	}
@@ -579,9 +595,9 @@ func parseECDSA(in []byte) (out PublicKey, rest []byte, err error) {
 	return (*ecdsaPublicKey)(key), w.Rest, nil
 }
 
-func (key *ecdsaPublicKey) Marshal() []byte {
+func (k *ecdsaPublicKey) Marshal() []byte {
 	// See RFC 5656, section 3.1.
-	keyBytes := elliptic.Marshal(key.Curve, key.X, key.Y)
+	keyBytes := elliptic.Marshal(k.Curve, k.X, k.Y)
 	// ECDSA publickey struct layout should match the struct used by
 	// parseECDSACert in the x/crypto/ssh/agent package.
 	w := struct {
@@ -589,20 +605,20 @@ func (key *ecdsaPublicKey) Marshal() []byte {
 		ID   string
 		Key  []byte
 	}{
-		key.Type(),
-		key.nistID(),
+		k.Type(),
+		k.nistID(),
 		keyBytes,
 	}
 
 	return Marshal(&w)
 }
 
-func (key *ecdsaPublicKey) Verify(data []byte, sig *Signature) error {
-	if sig.Format != key.Type() {
-		return fmt.Errorf("ssh: signature type %s for key type %s", sig.Format, key.Type())
+func (k *ecdsaPublicKey) Verify(data []byte, sig *Signature) error {
+	if sig.Format != k.Type() {
+		return fmt.Errorf("ssh: signature type %s for key type %s", sig.Format, k.Type())
 	}
 
-	h := ecHash(key.Curve).New()
+	h := ecHash(k.Curve).New()
 	h.Write(data)
 	digest := h.Sum(nil)
 
@@ -619,7 +635,7 @@ func (key *ecdsaPublicKey) Verify(data []byte, sig *Signature) error {
 		return err
 	}
 
-	if ecdsa.Verify((*ecdsa.PublicKey)(key), digest, ecSig.R, ecSig.S) {
+	if ecdsa.Verify((*ecdsa.PublicKey)(k), digest, ecSig.R, ecSig.S) {
 		return nil
 	}
 	return errors.New("ssh: signature did not verify")
@@ -630,19 +646,28 @@ func (k *ecdsaPublicKey) CryptoPublicKey() crypto.PublicKey {
 }
 
 // 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.
+// *ecdsa.PrivateKey or any other crypto.Signer and returns a
+// corresponding Signer instance. ECDSA keys must use P-256, P-384 or
+// P-521. DSA keys must use parameter size L1024N160.
 func NewSignerFromKey(key interface{}) (Signer, error) {
 	switch key := key.(type) {
 	case crypto.Signer:
 		return NewSignerFromSigner(key)
 	case *dsa.PrivateKey:
-		return &dsaPrivateKey{key}, nil
+		return newDSAPrivateKey(key)
 	default:
 		return nil, fmt.Errorf("ssh: unsupported key type %T", key)
 	}
 }
 
+func newDSAPrivateKey(key *dsa.PrivateKey) (Signer, error) {
+	if err := checkDSAParams(&key.PublicKey.Parameters); err != nil {
+		return nil, err
+	}
+
+	return &dsaPrivateKey{key}, nil
+}
+
 type wrappedSigner struct {
 	signer crypto.Signer
 	pubKey PublicKey
@@ -733,7 +758,7 @@ func NewPublicKey(key interface{}) (PublicKey, error) {
 		return (*rsaPublicKey)(key), nil
 	case *ecdsa.PublicKey:
 		if !supportedEllipticCurve(key.Curve) {
-			return nil, errors.New("ssh: only P-256, P-384 and P-521 EC keys are supported.")
+			return nil, errors.New("ssh: only P-256, P-384 and P-521 EC keys are supported")
 		}
 		return (*ecdsaPublicKey)(key), nil
 	case *dsa.PublicKey:
@@ -756,6 +781,18 @@ 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
@@ -790,6 +827,43 @@ func ParseRawPrivateKey(pemBytes []byte) (interface{}, error) {
 	}
 }
 
+// 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)
+	}
+}
+
 // ParseDSAPrivateKey returns a DSA private key from its ASN.1 DER encoding, as
 // specified by the OpenSSL DSA man page.
 func ParseDSAPrivateKey(der []byte) (*dsa.PrivateKey, error) {
@@ -824,7 +898,7 @@ func ParseDSAPrivateKey(der []byte) (*dsa.PrivateKey, error) {
 
 // Implemented based on the documentation at
 // https://github.com/openssh/openssh-portable/blob/master/PROTOCOL.key
-func parseOpenSSHPrivateKey(key []byte) (*ed25519.PrivateKey, error) {
+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")
@@ -844,14 +918,15 @@ func parseOpenSSHPrivateKey(key []byte) (*ed25519.PrivateKey, error) {
 		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
-		Pub     []byte
-		Priv    []byte
-		Comment string
-		Pad     []byte `ssh:"rest"`
+		Rest    []byte `ssh:"rest"`
 	}{}
 
 	if err := Unmarshal(w.PrivKeyBlock, &pk1); err != nil {
@@ -862,24 +937,75 @@ func parseOpenSSHPrivateKey(key []byte) (*ed25519.PrivateKey, error) {
 		return nil, errors.New("ssh: checkint mismatch")
 	}
 
-	// we only handle ed25519 keys currently
-	if pk1.Keytype != KeyAlgoED25519 {
+	// 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")
 	}
-
-	for i, b := range pk1.Pad {
-		if int(b) != i+1 {
-			return nil, errors.New("ssh: padding not as expected")
-		}
-	}
-
-	if len(pk1.Priv) != ed25519.PrivateKeySize {
-		return nil, errors.New("ssh: private key unexpected length")
-	}
-
-	pk := ed25519.PrivateKey(make([]byte, ed25519.PrivateKeySize))
-	copy(pk, pk1.Priv)
-	return &pk, nil
 }
 
 // FingerprintLegacyMD5 returns the user presentation of the key's
diff --git a/vendor/golang.org/x/crypto/ssh/messages.go b/vendor/golang.org/x/crypto/ssh/messages.go
index e6ecd3afa..08d281173 100644
--- a/vendor/golang.org/x/crypto/ssh/messages.go
+++ b/vendor/golang.org/x/crypto/ssh/messages.go
@@ -23,10 +23,6 @@ const (
 	msgUnimplemented = 3
 	msgDebug         = 4
 	msgNewKeys       = 21
-
-	// Standard authentication messages
-	msgUserAuthSuccess = 52
-	msgUserAuthBanner  = 53
 )
 
 // SSH messages:
@@ -137,6 +133,18 @@ type userAuthFailureMsg struct {
 	PartialSuccess bool
 }
 
+// See RFC 4252, section 5.1
+const msgUserAuthSuccess = 52
+
+// See RFC 4252, section 5.4
+const msgUserAuthBanner = 53
+
+type userAuthBannerMsg struct {
+	Message string `sshtype:"53"`
+	// unused, but required to allow message parsing
+	Language string
+}
+
 // See RFC 4256, section 3.2
 const msgUserAuthInfoRequest = 60
 const msgUserAuthInfoResponse = 61
@@ -154,7 +162,7 @@ const msgChannelOpen = 90
 
 type channelOpenMsg struct {
 	ChanType         string `sshtype:"90"`
-	PeersId          uint32
+	PeersID          uint32
 	PeersWindow      uint32
 	MaxPacketSize    uint32
 	TypeSpecificData []byte `ssh:"rest"`
@@ -165,7 +173,7 @@ const msgChannelData = 94
 
 // Used for debug print outs of packets.
 type channelDataMsg struct {
-	PeersId uint32 `sshtype:"94"`
+	PeersID uint32 `sshtype:"94"`
 	Length  uint32
 	Rest    []byte `ssh:"rest"`
 }
@@ -174,8 +182,8 @@ type channelDataMsg struct {
 const msgChannelOpenConfirm = 91
 
 type channelOpenConfirmMsg struct {
-	PeersId          uint32 `sshtype:"91"`
-	MyId             uint32
+	PeersID          uint32 `sshtype:"91"`
+	MyID             uint32
 	MyWindow         uint32
 	MaxPacketSize    uint32
 	TypeSpecificData []byte `ssh:"rest"`
@@ -185,7 +193,7 @@ type channelOpenConfirmMsg struct {
 const msgChannelOpenFailure = 92
 
 type channelOpenFailureMsg struct {
-	PeersId  uint32 `sshtype:"92"`
+	PeersID  uint32 `sshtype:"92"`
 	Reason   RejectionReason
 	Message  string
 	Language string
@@ -194,7 +202,7 @@ type channelOpenFailureMsg struct {
 const msgChannelRequest = 98
 
 type channelRequestMsg struct {
-	PeersId             uint32 `sshtype:"98"`
+	PeersID             uint32 `sshtype:"98"`
 	Request             string
 	WantReply           bool
 	RequestSpecificData []byte `ssh:"rest"`
@@ -204,28 +212,28 @@ type channelRequestMsg struct {
 const msgChannelSuccess = 99
 
 type channelRequestSuccessMsg struct {
-	PeersId uint32 `sshtype:"99"`
+	PeersID uint32 `sshtype:"99"`
 }
 
 // See RFC 4254, section 5.4.
 const msgChannelFailure = 100
 
 type channelRequestFailureMsg struct {
-	PeersId uint32 `sshtype:"100"`
+	PeersID uint32 `sshtype:"100"`
 }
 
 // See RFC 4254, section 5.3
 const msgChannelClose = 97
 
 type channelCloseMsg struct {
-	PeersId uint32 `sshtype:"97"`
+	PeersID uint32 `sshtype:"97"`
 }
 
 // See RFC 4254, section 5.3
 const msgChannelEOF = 96
 
 type channelEOFMsg struct {
-	PeersId uint32 `sshtype:"96"`
+	PeersID uint32 `sshtype:"96"`
 }
 
 // See RFC 4254, section 4
@@ -255,7 +263,7 @@ type globalRequestFailureMsg struct {
 const msgChannelWindowAdjust = 93
 
 type windowAdjustMsg struct {
-	PeersId         uint32 `sshtype:"93"`
+	PeersID         uint32 `sshtype:"93"`
 	AdditionalBytes uint32
 }
 
diff --git a/vendor/golang.org/x/crypto/ssh/mux.go b/vendor/golang.org/x/crypto/ssh/mux.go
index 27a527c10..f19016270 100644
--- a/vendor/golang.org/x/crypto/ssh/mux.go
+++ b/vendor/golang.org/x/crypto/ssh/mux.go
@@ -278,7 +278,7 @@ func (m *mux) handleChannelOpen(packet []byte) error {
 
 	if msg.MaxPacketSize < minPacketLength || msg.MaxPacketSize > 1<<31 {
 		failMsg := channelOpenFailureMsg{
-			PeersId:  msg.PeersId,
+			PeersID:  msg.PeersID,
 			Reason:   ConnectionFailed,
 			Message:  "invalid request",
 			Language: "en_US.UTF-8",
@@ -287,7 +287,7 @@ func (m *mux) handleChannelOpen(packet []byte) error {
 	}
 
 	c := m.newChannel(msg.ChanType, channelInbound, msg.TypeSpecificData)
-	c.remoteId = msg.PeersId
+	c.remoteId = msg.PeersID
 	c.maxRemotePayload = msg.MaxPacketSize
 	c.remoteWin.add(msg.PeersWindow)
 	m.incomingChannels <- c
@@ -313,7 +313,7 @@ func (m *mux) openChannel(chanType string, extra []byte) (*channel, error) {
 		PeersWindow:      ch.myWindow,
 		MaxPacketSize:    ch.maxIncomingPayload,
 		TypeSpecificData: extra,
-		PeersId:          ch.localId,
+		PeersID:          ch.localId,
 	}
 	if err := m.sendMessage(open); err != nil {
 		return nil, err
diff --git a/vendor/golang.org/x/crypto/ssh/server.go b/vendor/golang.org/x/crypto/ssh/server.go
index 77c84d165..b83d47388 100644
--- a/vendor/golang.org/x/crypto/ssh/server.go
+++ b/vendor/golang.org/x/crypto/ssh/server.go
@@ -14,23 +14,34 @@ import (
 )
 
 // 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
 }
 
@@ -45,13 +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 a nil error
+	// 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
@@ -73,6 +95,10 @@ type ServerConfig struct {
 	// Note that RFC 4253 section 4.2 requires that this string start with
 	// "SSH-2.0-".
 	ServerVersion string
+
+	// BannerCallback, if present, is called and the return string is sent to
+	// the client after key exchange completed but before authentication.
+	BannerCallback func(conn ConnMetadata) string
 }
 
 // AddHostKey adds a private key as a host key. If an existing host
@@ -143,6 +169,10 @@ 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},
 	}
@@ -226,7 +256,7 @@ func (s *connection) serverHandshake(config *ServerConfig) (*Permissions, error)
 func isAcceptableAlgo(algo string) bool {
 	switch algo {
 	case KeyAlgoRSA, KeyAlgoDSA, KeyAlgoECDSA256, KeyAlgoECDSA384, KeyAlgoECDSA521, KeyAlgoED25519,
-		CertAlgoRSAv01, CertAlgoDSAv01, CertAlgoECDSA256v01, CertAlgoECDSA384v01, CertAlgoECDSA521v01:
+		CertAlgoRSAv01, CertAlgoDSAv01, CertAlgoECDSA256v01, CertAlgoECDSA384v01, CertAlgoECDSA521v01, CertAlgoED25519v01:
 		return true
 	}
 	return false
@@ -262,15 +292,52 @@ func checkSourceAddress(addr net.Addr, sourceAddrs string) error {
 	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) {
 	sessionID := s.transport.getSessionID()
 	var cache pubKeyCache
 	var perms *Permissions
 
+	authFailures := 0
+	var authErrs []error
+	var displayedBanner bool
+
 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
@@ -281,6 +348,20 @@ userAuthLoop:
 		}
 
 		s.user = userAuthReq.User
+
+		if !displayedBanner && config.BannerCallback != nil {
+			displayedBanner = true
+			msg := config.BannerCallback(s)
+			if msg != "" {
+				bannerMsg := &userAuthBannerMsg{
+					Message: msg,
+				}
+				if err := s.transport.writePacket(Marshal(bannerMsg)); err != nil {
+					return nil, err
+				}
+			}
+		}
+
 		perms = nil
 		authErr := errors.New("no auth passed yet")
 
@@ -289,6 +370,11 @@ userAuthLoop:
 			if config.NoClientAuth {
 				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")
@@ -360,6 +446,7 @@ userAuthLoop:
 			if isQuery {
 				// The client can query if the given public key
 				// would be okay.
+
 				if len(payload) > 0 {
 					return nil, parseError(msgUserAuthRequest)
 				}
@@ -401,6 +488,8 @@ userAuthLoop:
 			authErr = fmt.Errorf("ssh: unknown method %q", userAuthReq.Method)
 		}
 
+		authErrs = append(authErrs, authErr)
+
 		if config.AuthLogCallback != nil {
 			config.AuthLogCallback(s, userAuthReq.Method, authErr)
 		}
@@ -409,6 +498,8 @@ userAuthLoop:
 			break userAuthLoop
 		}
 
+		authFailures++
+
 		var failureMsg userAuthFailureMsg
 		if config.PasswordCallback != nil {
 			failureMsg.Methods = append(failureMsg.Methods, "password")
diff --git a/vendor/golang.org/x/crypto/ssh/session.go b/vendor/golang.org/x/crypto/ssh/session.go
index 17e2aa85c..d3321f6b7 100644
--- a/vendor/golang.org/x/crypto/ssh/session.go
+++ b/vendor/golang.org/x/crypto/ssh/session.go
@@ -231,6 +231,26 @@ func (s *Session) RequestSubsystem(subsystem string) error {
 	return err
 }
 
+// RFC 4254 Section 6.7.
+type ptyWindowChangeMsg struct {
+	Columns uint32
+	Rows    uint32
+	Width   uint32
+	Height  uint32
+}
+
+// WindowChange informs the remote host about a terminal window dimension change to h rows and w columns.
+func (s *Session) WindowChange(h, w int) error {
+	req := ptyWindowChangeMsg{
+		Columns: uint32(w),
+		Rows:    uint32(h),
+		Width:   uint32(w * 8),
+		Height:  uint32(h * 8),
+	}
+	_, err := s.ch.SendRequest("window-change", false, Marshal(&req))
+	return err
+}
+
 // RFC 4254 Section 6.9.
 type signalMsg struct {
 	Signal string
@@ -386,7 +406,7 @@ func (s *Session) Wait() error {
 		s.stdinPipeWriter.Close()
 	}
 	var copyError error
-	for _ = range s.copyFuncs {
+	for range s.copyFuncs {
 		if err := <-s.errors; err != nil && copyError == nil {
 			copyError = err
 		}
diff --git a/vendor/golang.org/x/crypto/ssh/streamlocal.go b/vendor/golang.org/x/crypto/ssh/streamlocal.go
new file mode 100644
index 000000000..a2dccc64c
--- /dev/null
+++ b/vendor/golang.org/x/crypto/ssh/streamlocal.go
@@ -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",
+	}
+}
diff --git a/vendor/golang.org/x/crypto/ssh/tcpip.go b/vendor/golang.org/x/crypto/ssh/tcpip.go
index 6151241ff..acf17175d 100644
--- a/vendor/golang.org/x/crypto/ssh/tcpip.go
+++ b/vendor/golang.org/x/crypto/ssh/tcpip.go
@@ -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")
 }
diff --git a/vendor/golang.org/x/crypto/ssh/transport.go b/vendor/golang.org/x/crypto/ssh/transport.go
index f9780e0ae..01150eb89 100644
--- a/vendor/golang.org/x/crypto/ssh/transport.go
+++ b/vendor/golang.org/x/crypto/ssh/transport.go
@@ -76,17 +76,17 @@ 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 ciph, err := newPacketCipher(t.reader.dir, algs.r, kexResult); err != nil {
+	ciph, err := newPacketCipher(t.reader.dir, algs.r, kexResult)
+	if err != nil {
 		return err
-	} else {
-		t.reader.pendingKeyChange <- ciph
 	}
+	t.reader.pendingKeyChange <- ciph
 
-	if ciph, err := newPacketCipher(t.writer.dir, algs.w, kexResult); err != nil {
+	ciph, err = newPacketCipher(t.writer.dir, algs.w, kexResult)
+	if err != nil {
 		return err
-	} else {
-		t.writer.pendingKeyChange <- ciph
 	}
+	t.writer.pendingKeyChange <- ciph
 
 	return nil
 }
@@ -139,7 +139,7 @@ func (s *connectionState) readPacket(r *bufio.Reader) ([]byte, error) {
 			case cipher := <-s.pendingKeyChange:
 				s.packetCipher = cipher
 			default:
-				return nil, errors.New("ssh: got bogus newkeys message.")
+				return nil, errors.New("ssh: got bogus newkeys message")
 			}
 
 		case msgDisconnect:
@@ -254,7 +254,7 @@ func newPacketCipher(d direction, algs directionAlgorithms, kex *kexResult) (pac
 	iv, key, macKey := generateKeys(d, algs, kex)
 
 	if algs.Cipher == gcmCipherID {
-		return newGCMCipher(iv, key, macKey)
+		return newGCMCipher(iv, key)
 	}
 
 	if algs.Cipher == aes128cbcID {
diff --git a/vendor/vendor.json b/vendor/vendor.json
index 65fe2821d..9a6bf9748 100644
--- a/vendor/vendor.json
+++ b/vendor/vendor.json
@@ -2252,16 +2252,20 @@
 			"revisionTime": "2017-02-08T20:51:15Z"
 		},
 		{
-			"checksumSHA1": "fsrFs762jlaILyqqQImS1GfvIvw=",
+			"checksumSHA1": "pySTR3iSeU7FhjbBnQPNxgyIa4I=",
 			"path": "golang.org/x/crypto/ssh",
-			"revision": "453249f01cfeb54c3d549ddb75ff152ca243f9d8",
-			"revisionTime": "2017-02-08T20:51:15Z"
+			"revision": "d585fd2cc9195196078f516b69daff6744ef5e84",
+			"revisionTime": "2017-12-16T04:08:15Z",
+			"version": "master",
+			"versionExact": "master"
 		},
 		{
-			"checksumSHA1": "SJ3Ma3Ozavxpbh1usZWBCnzMKIc=",
+			"checksumSHA1": "NMRX0onGReaL9IfLr0XQ3kl5Id0=",
 			"path": "golang.org/x/crypto/ssh/agent",
-			"revision": "453249f01cfeb54c3d549ddb75ff152ca243f9d8",
-			"revisionTime": "2017-02-08T20:51:15Z"
+			"revision": "d585fd2cc9195196078f516b69daff6744ef5e84",
+			"revisionTime": "2017-12-16T04:08:15Z",
+			"version": "master",
+			"versionExact": "master"
 		},
 		{
 			"checksumSHA1": "9jjO5GjLa0XF/nfWihF02RoH4qc=",