agent

Documentation

Overview

Package agent implements the ssh-agent protocol, and provides both a client and a server. The client can talk to a standard ssh-agent that uses UNIX sockets, and one could implement an alternative ssh-agent process using the sample server.

References:

[PROTOCOL.agent]: https://tools.ietf.org/html/draft-miller-ssh-agent-00

Index

• func ForwardToAgent(client *ssh.Client, keyring Agent) error
• func ForwardToRemote(client *ssh.Client, addr string) error
• func RequestAgentForwarding(session *ssh.Session) error
• func ServeAgent(agent Agent, c io.ReadWriter) error
• type AddedKey
• type Agent
  • func NewClient(rw io.ReadWriter) Agent
  • func NewKeyring() Agent
• type ConstraintExtension
• type Key
  • func (k *Key) Marshal() []byte
  • func (k *Key) String() string
  • func (k *Key) Type() string
  • func (k *Key) Verify(data []byte, sig *ssh.Signature) error

Functions

func ForwardToAgent

func ForwardToAgent(client *ssh.Client, keyring Agent) error

ForwardToAgent routes authentication requests to the given keyring.

func ForwardToRemote

func ForwardToRemote(client *ssh.Client, addr string) error

ForwardToRemote routes authentication requests to the ssh-agent process serving on the given unix socket.

func RequestAgentForwarding

func RequestAgentForwarding(session *ssh.Session) error

RequestAgentForwarding sets up agent forwarding for the session. ForwardToAgent or ForwardToRemote should be called to route the authentication requests.

func ServeAgent

func ServeAgent(agent Agent, c io.ReadWriter) error

ServeAgent serves the agent protocol on the given connection. It returns when an I/O error occurs.

Types

type AddedKey

type AddedKey struct {
	// PrivateKey must be a *rsa.PrivateKey, *dsa.PrivateKey or
	// *ecdsa.PrivateKey, which will be inserted into the agent.
	PrivateKey interface{}
	// Certificate, if not nil, is communicated to the agent and will be
	// stored with the key.
	Certificate *ssh.Certificate
	// Comment is an optional, free-form string.
	Comment string
	// LifetimeSecs, if not zero, is the number of seconds that the
	// agent will store the key for.
	LifetimeSecs uint32
	// 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
}

AddedKey describes an SSH key to be added to an Agent.

type Agent

type Agent interface {
	// List returns the identities known to the agent.
	List() ([]*Key, error)

	// Sign has the agent sign the data using a protocol 2 key as defined
	// in [PROTOCOL.agent] section 2.6.2.
	Sign(key ssh.PublicKey, data []byte) (*ssh.Signature, error)

	// Add adds a private key to the agent.
	Add(key AddedKey) error

	// Remove removes all identities with the given public key.
	Remove(key ssh.PublicKey) error

	// RemoveAll removes all identities.
	RemoveAll() error

	// Lock locks the agent. Sign and Remove will fail, and List will empty an empty list.
	Lock(passphrase []byte) error

	// Unlock undoes the effect of Lock
	Unlock(passphrase []byte) error

	// Signers returns signers for all the known keys.
	Signers() ([]ssh.Signer, error)
}

Agent represents the capabilities of an ssh-agent.

func NewClient

func NewClient(rw io.ReadWriter) Agent

NewClient returns an Agent that talks to an ssh-agent process over the given connection.

func NewKeyring

func NewKeyring() Agent

NewKeyring returns an Agent that holds keys in memory. It is safe for concurrent use by multiple goroutines.

type ConstraintExtension

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
}

ConstraintExtension describes an optional constraint defined by users.

type Key

type Key struct {
	Format  string
	Blob    []byte
	Comment string
}

Key represents a protocol 2 public key as defined in [PROTOCOL.agent], section 2.5.2.

func (*Key) Marshal

func (k *Key) Marshal() []byte

Marshal returns key blob to satisfy the ssh.PublicKey interface.

func (*Key) String

func (k *Key) String() string

String returns the storage form of an agent key with the format, base64 encoded serialized key, and the comment if it is not empty.

func (*Key) Type

func (k *Key) Type() string

Type returns the public key type.

func (*Key) Verify

func (k *Key) Verify(data []byte, sig *ssh.Signature) error

Verify satisfies the ssh.PublicKey interface.