Certificate algorithm names from [PROTOCOL.certkeys]. These values can appear in Certificate.Type, PublicKey.Type, and ClientConfig.HostKeyAlgorithms. Unlike key algorithm names, these are not passed to AlgorithmSigner nor returned by MultiAlgorithmSigner and don't appear in the Signature.Format field.
const (
CertAlgoRSAv01 = "ssh-rsa-cert-v01@openssh.com"
CertAlgoDSAv01 = "ssh-dss-cert-v01@openssh.com"
CertAlgoECDSA256v01 = "ecdsa-sha2-nistp256-cert-v01@openssh.com"
CertAlgoECDSA384v01 = "ecdsa-sha2-nistp384-cert-v01@openssh.com"
CertAlgoECDSA521v01 = "ecdsa-sha2-nistp521-cert-v01@openssh.com"
CertAlgoSKECDSA256v01 = "sk-ecdsa-sha2-nistp256-cert-v01@openssh.com"
CertAlgoED25519v01 = "ssh-ed25519-cert-v01@openssh.com"
CertAlgoSKED25519v01 = "sk-ssh-ed25519-cert-v01@openssh.com"
// CertAlgoRSASHA256v01 and CertAlgoRSASHA512v01 can't appear as a
// Certificate.Type (or PublicKey.Type), but only in
// ClientConfig.HostKeyAlgorithms.
CertAlgoRSASHA256v01 = "rsa-sha2-256-cert-v01@openssh.com"
CertAlgoRSASHA512v01 = "rsa-sha2-512-cert-v01@openssh.com"
)
const (
// Deprecated: use CertAlgoRSAv01.
CertSigAlgoRSAv01 = CertAlgoRSAv01
// Deprecated: use CertAlgoRSASHA256v01.
CertSigAlgoRSASHA2256v01 = CertAlgoRSASHA256v01
// Deprecated: use CertAlgoRSASHA512v01.
CertSigAlgoRSASHA2512v01 = CertAlgoRSASHA512v01
)
Certificate types distinguish between host and user certificates. The values can be set in the CertType field of Certificate.
const (
UserCert = 1
HostCert = 2
)
Public key algorithms names. These values can appear in PublicKey.Type, ClientConfig.HostKeyAlgorithms, Signature.Format, or as AlgorithmSigner arguments.
const (
KeyAlgoRSA = "ssh-rsa"
KeyAlgoDSA = "ssh-dss"
KeyAlgoECDSA256 = "ecdsa-sha2-nistp256"
KeyAlgoSKECDSA256 = "sk-ecdsa-sha2-nistp256@openssh.com"
KeyAlgoECDSA384 = "ecdsa-sha2-nistp384"
KeyAlgoECDSA521 = "ecdsa-sha2-nistp521"
KeyAlgoED25519 = "ssh-ed25519"
KeyAlgoSKED25519 = "sk-ssh-ed25519@openssh.com"
// KeyAlgoRSASHA256 and KeyAlgoRSASHA512 are only public key algorithms, not
// public key formats, so they can't appear as a PublicKey.Type. The
// corresponding PublicKey.Type is KeyAlgoRSA. See RFC 8332, Section 2.
KeyAlgoRSASHA256 = "rsa-sha2-256"
KeyAlgoRSASHA512 = "rsa-sha2-512"
)
const (
// Deprecated: use KeyAlgoRSA.
SigAlgoRSA = KeyAlgoRSA
// Deprecated: use KeyAlgoRSASHA256.
SigAlgoRSASHA2256 = KeyAlgoRSASHA256
// Deprecated: use KeyAlgoRSASHA512.
SigAlgoRSASHA2512 = KeyAlgoRSASHA512
)
POSIX terminal mode flags as listed in RFC 4254 Section 8.
const (
VINTR = 1
VQUIT = 2
VERASE = 3
VKILL = 4
VEOF = 5
VEOL = 6
VEOL2 = 7
VSTART = 8
VSTOP = 9
VSUSP = 10
VDSUSP = 11
VREPRINT = 12
VWERASE = 13
VLNEXT = 14
VFLUSH = 15
VSWTCH = 16
VSTATUS = 17
VDISCARD = 18
IGNPAR = 30
PARMRK = 31
INPCK = 32
ISTRIP = 33
INLCR = 34
IGNCR = 35
ICRNL = 36
IUCLC = 37
IXON = 38
IXANY = 39
IXOFF = 40
IMAXBEL = 41
IUTF8 = 42 // RFC 8160
ISIG = 50
ICANON = 51
XCASE = 52
ECHO = 53
ECHOE = 54
ECHOK = 55
ECHONL = 56
NOFLSH = 57
TOSTOP = 58
IEXTEN = 59
ECHOCTL = 60
ECHOKE = 61
PENDIN = 62
OPOST = 70
OLCUC = 71
ONLCR = 72
OCRNL = 73
ONOCR = 74
ONLRET = 75
CS7 = 90
CS8 = 91
PARENB = 92
PARODD = 93
TTY_OP_ISPEED = 128
TTY_OP_OSPEED = 129
)
CertTimeInfinity can be used for OpenSSHCertV01.ValidBefore to indicate that a certificate does not expire.
const CertTimeInfinity = 1<<64 - 1
ErrNoAuth is the error value returned if no authentication method has been passed yet. This happens as a normal part of the authentication loop, since the client first tries 'none' authentication to discover available methods. It is returned in ServerAuthError.Errors from NewServerConn.
var ErrNoAuth = errors.New("ssh: no auth passed yet")
func DiscardRequests(in <-chan *Request)
DiscardRequests consumes and rejects all requests from the passed-in channel.
func FingerprintLegacyMD5(pubKey PublicKey) string
FingerprintLegacyMD5 returns the user presentation of the key's fingerprint as described by RFC 4716 section 4.
func FingerprintSHA256(pubKey PublicKey) string
FingerprintSHA256 returns the user presentation of the key's fingerprint as unpadded base64 encoded sha256 hash. This format was introduced from OpenSSH 6.8. https://www.openssh.com/txt/release-6.8 https://tools.ietf.org/html/rfc4648#section-3.2 (unpadded base64 encoding)
func Marshal(msg interface{}) []byte
Marshal serializes the message in msg to SSH wire format. The msg argument should be a struct or pointer to struct. If the first member has the "sshtype" tag set to a number in decimal, that number is prepended to the result. If the last of member has the "ssh" tag set to "rest", its contents are appended to the output.
func MarshalAuthorizedKey(key PublicKey) []byte
MarshalAuthorizedKey serializes key for inclusion in an OpenSSH authorized_keys file. The return value ends with newline.
func MarshalPrivateKey(key crypto.PrivateKey, comment string) (*pem.Block, error)
MarshalPrivateKey returns a PEM block with the private key serialized in the OpenSSH format.
func MarshalPrivateKeyWithPassphrase(key crypto.PrivateKey, comment string, passphrase []byte) (*pem.Block, error)
MarshalPrivateKeyWithPassphrase returns a PEM block holding the encrypted private key serialized in the OpenSSH format.
func ParseDSAPrivateKey(der []byte) (*dsa.PrivateKey, error)
ParseDSAPrivateKey returns a DSA private key from its ASN.1 DER encoding, as specified by the OpenSSL DSA man page.
func ParseRawPrivateKey(pemBytes []byte) (interface{}, error)
ParseRawPrivateKey returns a private key from a PEM encoded private key. It supports RSA, DSA, ECDSA, and Ed25519 private keys in PKCS#1, PKCS#8, OpenSSL, and OpenSSH formats. If the private key is encrypted, it will return a PassphraseMissingError.
func ParseRawPrivateKeyWithPassphrase(pemBytes, passphrase []byte) (interface{}, error)
ParseRawPrivateKeyWithPassphrase returns a private key decrypted with passphrase from a PEM encoded private key. If the passphrase is wrong, it will return x509.IncorrectPasswordError.
func Unmarshal(data []byte, out interface{}) error
Unmarshal parses data in SSH wire format into a structure. The out argument should be a pointer to struct. If the first member of the struct has the "sshtype" tag set to a '|'-separated set of numbers in decimal, the packet must start with one of those numbers. In case of error, Unmarshal returns a ParseError or UnexpectedMessageError.
An AlgorithmSigner is a Signer that also supports specifying an algorithm to use for signing.
An AlgorithmSigner can't advertise the algorithms it supports, unless it also implements MultiAlgorithmSigner, so it should be prepared to be invoked with every algorithm supported by the public key format.
type AlgorithmSigner interface {
Signer
// SignWithAlgorithm is like Signer.Sign, but allows specifying a desired
// signing algorithm. Callers may pass an empty string for the algorithm in
// which case the AlgorithmSigner will use a default algorithm. This default
// doesn't currently control any behavior in this package.
SignWithAlgorithm(rand io.Reader, data []byte, algorithm string) (*Signature, error)
}
An AuthMethod represents an instance of an RFC 4252 authentication method.
type AuthMethod interface {
// contains filtered or unexported methods
}
func GSSAPIWithMICAuthMethod(gssAPIClient GSSAPIClient, target string) AuthMethod
GSSAPIWithMICAuthMethod is an AuthMethod with "gssapi-with-mic" authentication. See RFC 4462 section 3 gssAPIClient is implementation of the GSSAPIClient interface, see the definition of the interface for details. target is the server host you want to log in to.
func KeyboardInteractive(challenge KeyboardInteractiveChallenge) AuthMethod
KeyboardInteractive returns an AuthMethod using a prompt/response sequence controlled by the server.
func Password(secret string) AuthMethod
Password returns an AuthMethod using the given password.
func PasswordCallback(prompt func() (secret string, err error)) AuthMethod
PasswordCallback returns an AuthMethod that uses a callback for fetching a password.
func PublicKeys(signers ...Signer) AuthMethod
PublicKeys returns an AuthMethod that uses the given key pairs.
▹ Example
func PublicKeysCallback(getSigners func() (signers []Signer, err error)) AuthMethod
PublicKeysCallback returns an AuthMethod that runs the given function to obtain a list of key pairs.
func RetryableAuthMethod(auth AuthMethod, maxTries int) AuthMethod
RetryableAuthMethod is a decorator for other auth methods enabling them to be retried up to maxTries before considering that AuthMethod itself failed. If maxTries is <= 0, will retry indefinitely
This is useful for interactive clients using challenge/response type authentication (e.g. Keyboard-Interactive, Password, etc) where the user could mistype their response resulting in the server issuing a SSH_MSG_USERAUTH_FAILURE (rfc4252 #8 [password] and rfc4256 #3.4 [keyboard-interactive]); Without this decorator, the non-retryable AuthMethod would be removed from future consideration, and never tried again (and so the user would never be able to retry their entry).
▹ Example
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
func BannerDisplayStderr() BannerCallback
BannerDisplayStderr returns a function that can be used for ClientConfig.BannerCallback to display banners on os.Stderr.
CertChecker does the work of verifying a certificate. Its methods can be plugged into ClientConfig.HostKeyCallback and ServerConfig.PublicKeyCallback. For the CertChecker to work, minimally, the IsAuthority callback should be set.
type CertChecker struct {
// SupportedCriticalOptions lists the CriticalOptions that the
// server application layer understands. These are only used
// for user certificates.
SupportedCriticalOptions []string
// 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.
Clock func() time.Time
// UserKeyFallback is called when CertChecker.Authenticate encounters a
// public key that is not a certificate. It must implement validation
// of user keys or else, if nil, all such keys are rejected.
UserKeyFallback func(conn ConnMetadata, key PublicKey) (*Permissions, error)
// 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 HostKeyCallback
// IsRevoked is called for each certificate so that revocation checking
// can be implemented. It should return true if the given certificate
// is revoked and false otherwise. If nil, no certificates are
// considered to have been revoked.
IsRevoked func(cert *Certificate) bool
}
func (c *CertChecker) Authenticate(conn ConnMetadata, pubKey PublicKey) (*Permissions, error)
Authenticate checks a user certificate. Authenticate can be used as a value for ServerConfig.PublicKeyCallback.
func (c *CertChecker) CheckCert(principal string, cert *Certificate) error
CheckCert checks CriticalOptions, ValidPrincipals, revocation, timestamp and the signature of the certificate.
func (c *CertChecker) CheckHostKey(addr string, remote net.Addr, key PublicKey) error
CheckHostKey checks a host key certificate. This method can be plugged into ClientConfig.HostKeyCallback.
An Certificate represents an OpenSSH certificate as defined in [PROTOCOL.certkeys]?rev=1.8. The Certificate type implements the PublicKey interface, so it can be unmarshaled using ParsePublicKey.
type Certificate struct {
Nonce []byte
Key PublicKey
Serial uint64
CertType uint32
KeyId string
ValidPrincipals []string
ValidAfter uint64
ValidBefore uint64
Permissions
Reserved []byte
SignatureKey PublicKey
Signature *Signature
}
func (c *Certificate) Marshal() []byte
Marshal serializes c into OpenSSH's wire format. It is part of the PublicKey interface.
func (c *Certificate) SignCert(rand io.Reader, authority Signer) error
SignCert signs the certificate with an authority, setting the Nonce, SignatureKey, and Signature fields. If the authority implements the MultiAlgorithmSigner interface the first algorithm in the list is used. This is useful if you want to sign with a specific algorithm.
▹ Example
func (c *Certificate) Type() string
Type returns the certificate algorithm name. It is part of the PublicKey interface.
func (c *Certificate) Verify(data []byte, sig *Signature) error
Verify verifies a signature against the certificate's public key. It is part of the PublicKey interface.
A Channel is an ordered, reliable, flow-controlled, duplex stream that is multiplexed over an SSH connection.
type Channel interface {
// Read reads up to len(data) bytes from the channel.
Read(data []byte) (int, error)
// Write writes len(data) bytes to the channel.
Write(data []byte) (int, error)
// Close signals end of channel use. No data may be sent after this
// call.
Close() error
// CloseWrite signals the end of sending in-band
// data. Requests may still be sent, and the other side may
// still send data
CloseWrite() error
// SendRequest sends a channel request. If wantReply is true,
// it will wait for a reply and return the result as a
// boolean, otherwise the return value will be false. Channel
// requests are out-of-band messages so they may be sent even
// if the data stream is closed or blocked by flow control.
// If the channel is closed before a reply is returned, io.EOF
// is returned.
SendRequest(name string, wantReply bool, payload []byte) (bool, error)
// Stderr returns an io.ReadWriter that writes to this channel
// with the extended data type set to stderr. Stderr may
// safely be read and written from a different goroutine than
// Read and Write respectively.
Stderr() io.ReadWriter
}
Client implements a traditional SSH client that supports shells, subprocesses, TCP port/streamlocal forwarding and tunneled dialing.
type Client struct {
Conn
// contains filtered or unexported fields
}
func Dial(network, addr string, config *ClientConfig) (*Client, error)
Dial starts a client connection to the given SSH server. It is a convenience function that connects to the given network address, initiates the SSH handshake, and then sets up a Client. For access to incoming channels and requests, use net.Dial with NewClientConn instead.
▹ Example
func NewClient(c Conn, chans <-chan NewChannel, reqs <-chan *Request) *Client
NewClient creates a Client on top of the given connection.
func (c *Client) Dial(n, addr string) (net.Conn, error)
Dial initiates a connection to the addr from the remote host. The resulting connection has a zero LocalAddr() and RemoteAddr().
func (c *Client) DialContext(ctx context.Context, n, addr string) (net.Conn, error)
DialContext initiates a connection to the addr from the remote host.
The provided Context must be non-nil. If the context expires before the connection is complete, an error is returned. Once successfully connected, any expiration of the context will not affect the connection.
See func Dial for additional information.
func (c *Client) DialTCP(n string, laddr, raddr *net.TCPAddr) (net.Conn, error)
DialTCP connects to the remote address raddr on the network net, which must be "tcp", "tcp4", or "tcp6". If laddr is not nil, it is used as the local address for the connection.
func (c *Client) HandleChannelOpen(channelType string) <-chan NewChannel
HandleChannelOpen returns a channel on which NewChannel requests for the given type are sent. If the type already is being handled, nil is returned. The channel is closed when the connection is closed.
func (c *Client) Listen(n, addr string) (net.Listener, error)
Listen requests the remote peer open a listening socket on 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".
▹ Example
func (c *Client) ListenTCP(laddr *net.TCPAddr) (net.Listener, error)
ListenTCP requests the remote peer open a listening socket on laddr. Incoming connections will be available by calling Accept on the returned net.Listener.
func (c *Client) ListenUnix(socketPath string) (net.Listener, error)
ListenUnix is similar to ListenTCP but uses a Unix domain socket.
func (c *Client) NewSession() (*Session, error)
NewSession opens a new Session for this client. (A session is a remote execution of a program.)
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 {
// Config contains configuration that is shared between clients and
// servers.
Config
// User contains the username to authenticate as.
User string
// Auth contains possible authentication methods to use with the
// server. Only the first instance of a particular RFC 4252 method will
// be used during authentication.
Auth []AuthMethod
// 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.
ClientVersion string
// HostKeyAlgorithms lists the public key algorithms that the client will
// accept from the server for host key authentication, in order of
// preference. If empty, a reasonable default is used. Any
// string returned from a PublicKey.Type method may be used, or
// any of the CertAlgo and KeyAlgo constants.
HostKeyAlgorithms []string
// Timeout is the maximum amount of time for the TCP connection to establish.
//
// A Timeout of zero means no timeout.
Timeout time.Duration
}
Config contains configuration data common to both ServerConfig and ClientConfig.
type Config struct {
// Rand provides the source of entropy for cryptographic
// primitives. If Rand is nil, the cryptographic random reader
// in package crypto/rand will be used.
Rand io.Reader
// The maximum number of bytes sent or received after which a
// new key is negotiated. It must be at least 256. If
// unspecified, a size suitable for the chosen cipher is used.
RekeyThreshold uint64
// The allowed key exchanges algorithms. If unspecified then a default set
// of algorithms is used. Unsupported values are silently ignored.
KeyExchanges []string
// The allowed cipher algorithms. If unspecified then a sensible default is
// used. Unsupported values are silently ignored.
Ciphers []string
// The allowed MAC algorithms. If unspecified then a sensible default is
// used. Unsupported values are silently ignored.
MACs []string
}
func (c *Config) SetDefaults()
SetDefaults sets sensible values for unset fields in config. This is exported for testing: Configs passed to SSH functions are copied and have default values set automatically.
Conn represents an SSH connection for both server and client roles. Conn is the basis for implementing an application layer, such as ClientConn, which implements the traditional shell access for clients.
type Conn interface {
ConnMetadata
// SendRequest sends a global request, and returns the
// reply. If wantReply is true, it returns the response status
// and payload. See also RFC 4254, section 4.
SendRequest(name string, wantReply bool, payload []byte) (bool, []byte, error)
// OpenChannel tries to open an channel. If the request is
// rejected, it returns *OpenChannelError. On success it returns
// the SSH Channel and a Go channel for incoming, out-of-band
// requests. The Go channel must be serviced, or the
// connection will hang.
OpenChannel(name string, data []byte) (Channel, <-chan *Request, error)
// Close closes the underlying network connection
Close() error
// Wait blocks until the connection has shut down, and returns the
// error causing the shutdown.
Wait() error
}
func NewClientConn(c net.Conn, addr string, config *ClientConfig) (Conn, <-chan NewChannel, <-chan *Request, error)
NewClientConn establishes an authenticated SSH connection using c as the underlying transport. The Request and NewChannel channels must be serviced or the connection will hang.
ConnMetadata holds metadata for the connection.
type ConnMetadata interface {
// User returns the user ID for this connection.
User() string
// SessionID returns the session hash, also denoted by H.
SessionID() []byte
// ClientVersion returns the client's version string as hashed
// into the session ID.
ClientVersion() []byte
// ServerVersion returns the server's version string as hashed
// into the session ID.
ServerVersion() []byte
// RemoteAddr returns the remote address for this connection.
RemoteAddr() net.Addr
// LocalAddr returns the local address for this connection.
LocalAddr() net.Addr
}
CryptoPublicKey, if implemented by a PublicKey, returns the underlying crypto.PublicKey form of the key.
type CryptoPublicKey interface {
CryptoPublicKey() crypto.PublicKey
}
An ExitError reports unsuccessful completion of a remote command.
type ExitError struct {
Waitmsg
}
func (e *ExitError) Error() string
ExitMissingError is returned if a session is torn down cleanly, but the server sends no confirmation of the exit status.
type ExitMissingError struct{}
func (e *ExitMissingError) Error() string
GSSAPIClient provides the API to plug-in GSSAPI authentication for client logins.
type GSSAPIClient interface {
// InitSecContext initiates the establishment of a security context for GSS-API between the
// ssh client and ssh server. Initially the token parameter should be specified as nil.
// The routine may return a outputToken which should be transferred to
// the ssh server, where the ssh server will present it to
// AcceptSecContext. If no token need be sent, InitSecContext will indicate this by setting
// needContinue to false. To complete the context
// establishment, one or more reply tokens may be required from the ssh
// server;if so, InitSecContext will return a needContinue which is true.
// In this case, InitSecContext should be called again when the
// reply token is received from the ssh server, passing the reply
// token to InitSecContext via the token parameters.
// See RFC 2743 section 2.2.1 and RFC 4462 section 3.4.
InitSecContext(target string, token []byte, isGSSDelegCreds bool) (outputToken []byte, needContinue bool, err error)
// GetMIC generates a cryptographic MIC for the SSH2 message, and places
// the MIC in a token for transfer to the ssh server.
// The contents of the MIC field are obtained by calling GSS_GetMIC()
// over the following, using the GSS-API context that was just
// established:
// string session identifier
// byte SSH_MSG_USERAUTH_REQUEST
// string user name
// string service
// string "gssapi-with-mic"
// See RFC 2743 section 2.3.1 and RFC 4462 3.5.
GetMIC(micFiled []byte) ([]byte, error)
// Whenever possible, it should be possible for
// DeleteSecContext() calls to be successfully processed even
// if other calls cannot succeed, thereby enabling context-related
// resources to be released.
// In addition to deleting established security contexts,
// gss_delete_sec_context must also be able to delete "half-built"
// security contexts resulting from an incomplete sequence of
// InitSecContext()/AcceptSecContext() calls.
// See RFC 2743 section 2.2.3.
DeleteSecContext() error
}
GSSAPIServer provides the API to plug in GSSAPI authentication for server logins.
type GSSAPIServer interface {
// AcceptSecContext allows a remotely initiated security context between the application
// and a remote peer to be established by the ssh client. The routine may return a
// outputToken which should be transferred to the ssh client,
// where the ssh client will present it to InitSecContext.
// If no token need be sent, AcceptSecContext will indicate this
// by setting the needContinue to false. To
// complete the context establishment, one or more reply tokens may be
// required from the ssh client. if so, AcceptSecContext
// will return a needContinue which is true, in which case it
// should be called again when the reply token is received from the ssh
// client, passing the token to AcceptSecContext via the
// token parameters.
// The srcName return value is the authenticated username.
// See RFC 2743 section 2.2.2 and RFC 4462 section 3.4.
AcceptSecContext(token []byte) (outputToken []byte, srcName string, needContinue bool, err error)
// VerifyMIC verifies that a cryptographic MIC, contained in the token parameter,
// fits the supplied message is received from the ssh client.
// See RFC 2743 section 2.3.2.
VerifyMIC(micField []byte, micToken []byte) error
// Whenever possible, it should be possible for
// DeleteSecContext() calls to be successfully processed even
// if other calls cannot succeed, thereby enabling context-related
// resources to be released.
// In addition to deleting established security contexts,
// gss_delete_sec_context must also be able to delete "half-built"
// security contexts resulting from an incomplete sequence of
// InitSecContext()/AcceptSecContext() calls.
// See RFC 2743 section 2.2.3.
DeleteSecContext() error
}
type GSSAPIWithMICConfig struct {
// AllowLogin, must be set, is called when gssapi-with-mic
// authentication is selected (RFC 4462 section 3). The srcName is from the
// results of the GSS-API authentication. The format is username@DOMAIN.
// GSSAPI just guarantees to the server who the user is, but not if they can log in, and with what permissions.
// This callback is called after the user identity is established with GSSAPI to decide if the user can login with
// which permissions. If the user is allowed to login, it should return a nil error.
AllowLogin func(conn ConnMetadata, srcName string) (*Permissions, error)
// Server must be set. It's the implementation
// of the GSSAPIServer interface. See GSSAPIServer interface for details.
Server GSSAPIServer
}
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 SSH connection.
type HostKeyCallback func(hostname string, remote net.Addr, key PublicKey) error
func FixedHostKey(key PublicKey) HostKeyCallback
FixedHostKey returns a function for use in ClientConfig.HostKeyCallback to accept only a specific host key.
func InsecureIgnoreHostKey() HostKeyCallback
InsecureIgnoreHostKey returns a function that can be used for ClientConfig.HostKeyCallback to accept any host key. It should not be used for production code.
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 successful authentication, the server may send a challenge with no questions, for which the name and instruction messages should be printed. RFC 4256 section 3.3 details how the UI should behave for both CLI and GUI environments.
type KeyboardInteractiveChallenge func(name, instruction string, questions []string, echos []bool) (answers []string, err error)
MultiAlgorithmSigner is an AlgorithmSigner that also reports the algorithms supported by that signer.
type MultiAlgorithmSigner interface {
AlgorithmSigner
// Algorithms returns the available algorithms in preference order. The list
// must not be empty, and it must not include certificate types.
Algorithms() []string
}
func NewSignerWithAlgorithms(signer AlgorithmSigner, algorithms []string) (MultiAlgorithmSigner, error)
NewSignerWithAlgorithms returns a signer restricted to the specified algorithms. The algorithms must be set in preference order. The list must not be empty, and it must not include certificate types. An error is returned if the specified algorithms are incompatible with the public key type.
NewChannel represents an incoming request to a channel. It must either be accepted for use by calling Accept, or rejected by calling Reject.
type NewChannel interface {
// Accept accepts the channel creation request. It returns the Channel
// and a Go channel containing SSH requests. The Go channel must be
// serviced otherwise the Channel will hang.
Accept() (Channel, <-chan *Request, error)
// Reject rejects the channel creation request. After calling
// this, no other methods on the Channel may be called.
Reject(reason RejectionReason, message string) error
// ChannelType returns the type of the channel, as supplied by the
// client.
ChannelType() string
// ExtraData returns the arbitrary payload for this channel, as supplied
// by the client. This data is specific to the channel type.
ExtraData() []byte
}
OpenChannelError is returned if the other side rejects an OpenChannel request.
type OpenChannelError struct {
Reason RejectionReason
Message string
}
func (e *OpenChannelError) Error() string
A PassphraseMissingError indicates that parsing this private key requires a passphrase. Use ParsePrivateKeyWithPassphrase.
type PassphraseMissingError struct {
// PublicKey will be set if the private key format includes an unencrypted
// public key along with the encrypted private key.
PublicKey PublicKey
}
func (*PassphraseMissingError) Error() string
The Permissions type holds fine-grained permissions that are 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 {
// 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. 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
}
PublicKey represents a public key using an unspecified algorithm.
Some PublicKeys provided by this package also implement CryptoPublicKey.
type PublicKey interface {
// Type returns the key format name, e.g. "ssh-rsa".
Type() string
// Marshal returns the serialized key data in SSH wire format, with the name
// prefix. To unmarshal the returned data, use the ParsePublicKey function.
Marshal() []byte
// Verify that sig is a signature on the given data using this key. This
// method will hash the data appropriately first. sig.Format is allowed to
// be any signature algorithm compatible with the key type, the caller
// should check if it has more stringent requirements.
Verify(data []byte, sig *Signature) error
}
func NewPublicKey(key interface{}) (PublicKey, error)
NewPublicKey takes an *rsa.PublicKey, *dsa.PublicKey, *ecdsa.PublicKey, or ed25519.PublicKey returns a corresponding PublicKey instance. ECDSA keys must use P-256, P-384 or P-521.
func ParseAuthorizedKey(in []byte) (out PublicKey, comment string, options []string, rest []byte, err error)
ParseAuthorizedKey parses a public key from an authorized_keys file used in OpenSSH according to the sshd(8) manual page.
func ParseKnownHosts(in []byte) (marker string, hosts []string, pubKey PublicKey, comment string, rest []byte, err error)
ParseKnownHosts parses an entry in the format of the known_hosts file.
The known_hosts format is documented in the sshd(8) manual page. This function will parse a single entry from in. On successful return, marker will contain the optional marker value (i.e. "cert-authority" or "revoked") or else be empty, hosts will contain the hosts that this entry matches, pubKey will contain the public key and comment will contain any trailing comment at the end of the line. See the sshd(8) manual page for the various forms that a host string can take.
The unparsed remainder of the input will be returned in rest. This function can be called repeatedly to parse multiple entries.
If no entries were found in the input then err will be io.EOF. Otherwise a non-nil err value indicates a parse error.
func ParsePublicKey(in []byte) (out PublicKey, err error)
ParsePublicKey parses an SSH public key formatted for use in the SSH wire protocol according to RFC 4253, section 6.6.
RejectionReason is an enumeration used when rejecting channel creation requests. See RFC 4254, section 5.1.
type RejectionReason uint32
const (
Prohibited RejectionReason = iota + 1
ConnectionFailed
UnknownChannelType
ResourceShortage
)
func (r RejectionReason) String() string
String converts the rejection reason to human readable form.
Request is a request sent outside of the normal stream of data. Requests can either be specific to an SSH channel, or they can be global.
type Request struct {
Type string
WantReply bool
Payload []byte
// contains filtered or unexported fields
}
func (r *Request) Reply(ok bool, payload []byte) error
Reply sends a response to a request. It must be called for all requests where WantReply is true and is a no-op otherwise. The payload argument is ignored for replies to channel-specific requests.
ServerAuthError represents server authentication errors and is sometimes returned by NewServerConn. 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. The first entry is typically ErrNoAuth.
Errors []error
}
func (l ServerAuthError) Error() string
ServerConfig holds server specific configuration data.
type ServerConfig struct {
// Config contains configuration shared between client and server.
Config
// PublicKeyAuthAlgorithms specifies the supported client public key
// authentication algorithms. Note that this should not include certificate
// types since those use the underlying algorithm. This list is sent to the
// client if it supports the server-sig-algs extension. Order is irrelevant.
// If unspecified then a default set of algorithms is used.
PublicKeyAuthAlgorithms []string
// NoClientAuth is true if clients are allowed to connect without
// authenticating.
// To determine NoClientAuth at runtime, set NoClientAuth to true
// and the optional NoClientAuthCallback to a non-nil value.
NoClientAuth bool
// NoClientAuthCallback, if non-nil, is called when a user
// attempts to authenticate with auth method "none".
// NoClientAuth must also be set to true for this be used, or
// this func is unused.
NoClientAuthCallback func(ConnMetadata) (*Permissions, error)
// 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
// 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
// keyboard-interactive authentication is selected (RFC
// 4256). The client object's Challenge function should be
// used to query the user. The callback may offer multiple
// Challenge rounds. To avoid information leaks, the client
// should be presented a challenge even if the user is
// unknown.
KeyboardInteractiveCallback func(conn ConnMetadata, client KeyboardInteractiveChallenge) (*Permissions, error)
// AuthLogCallback, if non-nil, is called to log all authentication
// attempts.
AuthLogCallback func(conn ConnMetadata, method string, err error)
// ServerVersion is the version identification string to announce in
// the public handshake.
// If empty, a reasonable default is used.
// 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
// GSSAPIWithMICConfig includes gssapi server and callback, which if both non-nil, is used
// when gssapi-with-mic authentication is selected (RFC 4462 section 3).
GSSAPIWithMICConfig *GSSAPIWithMICConfig
// contains filtered or unexported fields
}
func (s *ServerConfig) AddHostKey(key Signer)
AddHostKey adds a private key as a host key. If an existing host key exists with the same public key format, it is replaced. Each server config must have at least one host key.
▹ Example
ServerConn is an authenticated SSH connection, as seen from the server
type ServerConn struct {
Conn
// If the succeeding authentication callback returned a
// non-nil Permissions pointer, it is stored here.
Permissions *Permissions
}
func NewServerConn(c net.Conn, config *ServerConfig) (*ServerConn, <-chan NewChannel, <-chan *Request, error)
NewServerConn starts a new SSH server with c as the underlying transport. It starts with a handshake and, if the handshake is unsuccessful, it closes the connection and returns an error. The Request and NewChannel channels must be serviced, or the connection will hang.
The returned error may be of type *ServerAuthError for authentication errors.
▹ Example
A Session represents a connection to a remote command or shell.
type Session struct {
// Stdin specifies the remote process's standard input.
// If Stdin is nil, the remote process reads from an empty
// bytes.Buffer.
Stdin io.Reader
// Stdout and Stderr specify the remote process's standard
// output and error.
//
// If either is nil, Run connects the corresponding file
// descriptor to an instance of io.Discard. There is a
// fixed amount of buffering that is shared for the two streams.
// If either blocks it may eventually cause the remote
// command to block.
Stdout io.Writer
Stderr io.Writer
// contains filtered or unexported fields
}
func (s *Session) Close() error
func (s *Session) CombinedOutput(cmd string) ([]byte, error)
CombinedOutput runs cmd on the remote host and returns its combined standard output and standard error.
func (s *Session) Output(cmd string) ([]byte, error)
Output runs cmd on the remote host and returns its standard output.
func (s *Session) RequestPty(term string, h, w int, termmodes TerminalModes) error
RequestPty requests the association of a pty with the session on the remote host.
▹ Example
func (s *Session) RequestSubsystem(subsystem string) error
RequestSubsystem requests the association of a subsystem with the session on the remote host. A subsystem is a predefined command that runs in the background when the ssh session is initiated
func (s *Session) Run(cmd string) error
Run runs cmd on the remote host. Typically, the remote server passes cmd to the shell for interpretation. A Session only accepts one call to Run, Start, Shell, Output, or CombinedOutput.
The returned error is nil if the command runs, has no problems copying stdin, stdout, and stderr, and exits with a zero exit status.
If the remote server does not send an exit status, an error of type *ExitMissingError is returned. If the command completes unsuccessfully or is interrupted by a signal, the error is of type *ExitError. Other error types may be returned for I/O problems.
func (s *Session) SendRequest(name string, wantReply bool, payload []byte) (bool, error)
SendRequest sends an out-of-band channel request on the SSH channel underlying the session.
func (s *Session) Setenv(name, value string) error
Setenv sets an environment variable that will be applied to any command executed by Shell or Run.
func (s *Session) Shell() error
Shell starts a login shell on the remote host. A Session only accepts one call to Run, Start, Shell, Output, or CombinedOutput.
func (s *Session) Signal(sig Signal) error
Signal sends the given signal to the remote process. sig is one of the SIG* constants.
func (s *Session) Start(cmd string) error
Start runs cmd on the remote host. Typically, the remote server passes cmd to the shell for interpretation. A Session only accepts one call to Run, Start or Shell.
func (s *Session) StderrPipe() (io.Reader, error)
StderrPipe returns a pipe that will be connected to the remote command's standard error when the command starts. There is a fixed amount of buffering that is shared between stdout and stderr streams. If the StderrPipe reader is not serviced fast enough it may eventually cause the remote command to block.
func (s *Session) StdinPipe() (io.WriteCloser, error)
StdinPipe returns a pipe that will be connected to the remote command's standard input when the command starts.
func (s *Session) StdoutPipe() (io.Reader, error)
StdoutPipe returns a pipe that will be connected to the remote command's standard output when the command starts. There is a fixed amount of buffering that is shared between stdout and stderr streams. If the StdoutPipe reader is not serviced fast enough it may eventually cause the remote command to block.
func (s *Session) Wait() error
Wait waits for the remote command to exit.
The returned error is nil if the command runs, has no problems copying stdin, stdout, and stderr, and exits with a zero exit status.
If the remote server does not send an exit status, an error of type *ExitMissingError is returned. If the command completes unsuccessfully or is interrupted by a signal, the error is of type *ExitError. Other error types may be returned for I/O problems.
func (s *Session) WindowChange(h, w int) error
WindowChange informs the remote host about a terminal window dimension change to h rows and w columns.
type Signal string
POSIX signals as listed in RFC 4254 Section 6.10.
const (
SIGABRT Signal = "ABRT"
SIGALRM Signal = "ALRM"
SIGFPE Signal = "FPE"
SIGHUP Signal = "HUP"
SIGILL Signal = "ILL"
SIGINT Signal = "INT"
SIGKILL Signal = "KILL"
SIGPIPE Signal = "PIPE"
SIGQUIT Signal = "QUIT"
SIGSEGV Signal = "SEGV"
SIGTERM Signal = "TERM"
SIGUSR1 Signal = "USR1"
SIGUSR2 Signal = "USR2"
)
Signature represents a cryptographic signature.
type Signature struct {
Format string
Blob []byte
Rest []byte `ssh:"rest"`
}
A Signer can create signatures that verify against a public key.
Some Signers provided by this package also implement MultiAlgorithmSigner.
type Signer interface {
// PublicKey returns the associated PublicKey.
PublicKey() PublicKey
// Sign returns a signature for the given data. This method will hash the
// data appropriately first. The signature algorithm is expected to match
// the key format returned by the PublicKey.Type method (and not to be any
// alternative algorithm supported by the key format).
Sign(rand io.Reader, data []byte) (*Signature, error)
}
func NewCertSigner(cert *Certificate, signer Signer) (Signer, error)
NewCertSigner returns a Signer that signs with the given Certificate, whose private key is held by signer. It returns an error if the public key in cert doesn't match the key used by signer.
func NewSignerFromKey(key interface{}) (Signer, error)
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. DSA keys must use parameter size L1024N160.
func NewSignerFromSigner(signer crypto.Signer) (Signer, error)
NewSignerFromSigner takes any crypto.Signer implementation and returns a corresponding Signer interface. This can be used, for example, with keys kept in hardware modules.
func ParsePrivateKey(pemBytes []byte) (Signer, error)
ParsePrivateKey returns a Signer from a PEM encoded private key. It supports the same keys as ParseRawPrivateKey. If the private key is encrypted, it will return a PassphraseMissingError.
func ParsePrivateKeyWithPassphrase(pemBytes, passphrase []byte) (Signer, error)
ParsePrivateKeyWithPassphrase returns a Signer from a PEM encoded private key and passphrase. It supports the same keys as ParseRawPrivateKeyWithPassphrase.
type TerminalModes map[uint8]uint32
Waitmsg stores the information about an exited remote command as reported by Wait.
type Waitmsg struct {
// contains filtered or unexported fields
}
func (w Waitmsg) ExitStatus() int
ExitStatus returns the exit status of the remote command.
func (w Waitmsg) Lang() string
Lang returns the language tag. See RFC 3066
func (w Waitmsg) Msg() string
Msg returns the exit message given by the remote command
func (w Waitmsg) Signal() string
Signal returns the exit signal of the remote command if it was terminated violently.
func (w Waitmsg) String() string
| Name | Synopsis |
|---|---|
| .. | |
| agent | Package agent implements the ssh-agent protocol, and provides both a client and a server. |
| knownhosts | Package knownhosts implements a parser for the OpenSSH known_hosts host key database, and provides utility functions for writing OpenSSH compliant known_hosts files. |
| terminal | Package terminal provides support functions for dealing with terminals, as commonly found on UNIX systems. |
| test | Package test contains integration tests for the golang.org/x/crypto/ssh package. |