class Net::SSH::Authentication::Agent

This class implements a simple client for the ssh-agent protocol. It does not implement any specific protocol, but instead copies the behavior of the ssh-agent functions in the OpenSSH library (3.8).

This means that although it behaves like a SSH1 client, it also has some SSH2 functionality (like signing data).

Constants

SSH2_AGENT_ADD_IDENTITY
SSH2_AGENT_ADD_ID_CONSTRAINED
SSH2_AGENT_FAILURE
SSH2_AGENT_IDENTITIES_ANSWER
SSH2_AGENT_REMOVE_ALL_IDENTITIES
SSH2_AGENT_REMOVE_IDENTITY
SSH2_AGENT_REQUEST_IDENTITIES
SSH2_AGENT_REQUEST_VERSION
SSH2_AGENT_SIGN_REQUEST
SSH2_AGENT_SIGN_RESPONSE
SSH2_AGENT_VERSION_RESPONSE
SSH_AGENT_CONSTRAIN_CONFIRM
SSH_AGENT_CONSTRAIN_LIFETIME
SSH_AGENT_FAILURE
SSH_AGENT_REQUEST_RSA_IDENTITIES
SSH_AGENT_RSA_IDENTITIES_ANSWER1
SSH_AGENT_RSA_IDENTITIES_ANSWER2
SSH_AGENT_RSA_SHA2_256
SSH_AGENT_RSA_SHA2_512
SSH_AGENT_SUCCESS
SSH_COM_AGENT2_FAILURE

Attributes

socket[R]

The underlying socket being used to communicate with the SSH agent.

Public Class Methods

connect(logger=nil, agent_socket_factory = nil, identity_agent = nil) click to toggle source

Instantiates a new agent object, connects to a running SSH agent, negotiates the agent protocol version, and returns the agent object.

# File lib/net/ssh/authentication/agent.rb, line 65
def self.connect(logger=nil, agent_socket_factory = nil, identity_agent = nil)
  agent = new(logger)
  agent.connect!(agent_socket_factory, identity_agent)
  agent.negotiate!
  agent
end

new(logger=nil) click to toggle source

Creates a new Agent object, using the optional logger instance to report status.

# File lib/net/ssh/authentication/agent.rb, line 74
def initialize(logger=nil)
  self.logger = logger
end

Public Instance Methods

add_identity(priv_key, comment, lifetime: nil, confirm: false) click to toggle source

Adds the private key with comment to the agent. If lifetime is given, the key will automatically be removed after lifetime seconds. If confirm is true, confirmation will be required for each agent signing operation.

# File lib/net/ssh/authentication/agent.rb, line 166
def add_identity(priv_key, comment, lifetime: nil, confirm: false)
  constraints = Buffer.new
  if lifetime
    constraints.write_byte(SSH_AGENT_CONSTRAIN_LIFETIME)
    constraints.write_long(lifetime)
  end
  constraints.write_byte(SSH_AGENT_CONSTRAIN_CONFIRM) if confirm

  req_type = constraints.empty? ? SSH2_AGENT_ADD_IDENTITY : SSH2_AGENT_ADD_ID_CONSTRAINED
  type, = send_and_wait(req_type, :string, priv_key.ssh_type, :raw, blob_for_add(priv_key),
              :string, comment, :raw, constraints)
  raise AgentError, "could not add identity to agent" if type != SSH_AGENT_SUCCESS
end

close() click to toggle source

Closes this socket. This agent reference is no longer able to query the agent.

# File lib/net/ssh/authentication/agent.rb, line 146
def close
  @socket.close
end

connect!(agent_socket_factory = nil, identity_agent = nil) click to toggle source

Connect to the agent process using the socket factory and socket name given by the attribute writers. If the agent on the other end of the socket reports that it is an SSH2-compatible agent, this will fail (it only supports the ssh-agent distributed by OpenSSH).

# File lib/net/ssh/authentication/agent.rb, line 82
def connect!(agent_socket_factory = nil, identity_agent = nil)
  debug { "connecting to ssh-agent" }
  @socket =
    if agent_socket_factory
      agent_socket_factory.call
    elsif identity_agent
      unix_socket_class.open(identity_agent)
    elsif ENV['SSH_AUTH_SOCK'] && unix_socket_class
      unix_socket_class.open(ENV['SSH_AUTH_SOCK'])
    elsif Gem.win_platform? && RUBY_ENGINE != "jruby"
      Pageant::Socket.open
    else
      raise AgentNotAvailable, "Agent not configured"
    end
rescue StandardError => e
  error { "could not connect to ssh-agent: #{e.message}" }
  raise AgentNotAvailable, $!.message
end

identities() click to toggle source

Return an array of all identities (public keys) known to the agent. Each key returned is augmented with a comment property which is set to the comment returned by the agent for that key.

# File lib/net/ssh/authentication/agent.rb, line 118
def identities
  type, body = send_and_wait(SSH2_AGENT_REQUEST_IDENTITIES)
  raise AgentError, "could not get identity count" if agent_failed(type)
  raise AgentError, "bad authentication reply: #{type}" if type != SSH2_AGENT_IDENTITIES_ANSWER

  identities = []
  body.read_long.times do
    key_str = body.read_string
    comment_str = body.read_string
    begin
      key = Buffer.new(key_str).read_key
      if key.nil?
        error { "ignoring invalid key: #{comment_str}" }
        next
      end
      key.extend(Comment)
      key.comment = comment_str
      identities.push key
    rescue NotImplementedError => e
      error { "ignoring unimplemented key:#{e.message} #{comment_str}" }
    end
  end

  return identities
end

negotiate!() click to toggle source

Attempts to negotiate the SSH agent protocol version. Raises an error if the version could not be negotiated successfully.

# File lib/net/ssh/authentication/agent.rb, line 103
def negotiate!
  # determine what type of agent we're communicating with
  type, body = send_and_wait(SSH2_AGENT_REQUEST_VERSION, :string, Transport::ServerVersion::PROTO_VERSION)

  raise AgentNotAvailable, "SSH2 agents are not yet supported" if type == SSH2_AGENT_VERSION_RESPONSE
  if type == SSH2_AGENT_FAILURE
    debug { "Unexpected response type==#{type}, this will be ignored" }
  elsif type != SSH_AGENT_RSA_IDENTITIES_ANSWER1 && type != SSH_AGENT_RSA_IDENTITIES_ANSWER2
    raise AgentNotAvailable, "unknown response from agent: #{type}, #{body.to_s.inspect}"
  end
end

remove_all_identities() click to toggle source

Removes all identities from the agent.

# File lib/net/ssh/authentication/agent.rb, line 187
def remove_all_identities
  type, = send_and_wait(SSH2_AGENT_REMOVE_ALL_IDENTITIES)
  raise AgentError, "could not remove all identity from agent" if type != SSH_AGENT_SUCCESS
end

remove_identity(key) click to toggle source

Removes key from the agent.

# File lib/net/ssh/authentication/agent.rb, line 181
def remove_identity(key)
  type, = send_and_wait(SSH2_AGENT_REMOVE_IDENTITY, :string, key.to_blob)
  raise AgentError, "could not remove identity from agent" if type != SSH_AGENT_SUCCESS
end

sign(key, data, flags = 0) click to toggle source

Using the agent and the given public key, sign the given data. The signature is returned in SSH2 format.

# File lib/net/ssh/authentication/agent.rb, line 152
def sign(key, data, flags = 0)
  type, reply = send_and_wait(SSH2_AGENT_SIGN_REQUEST, :string, Buffer.from(:key, key), :string, data, :long, flags)

  raise AgentError, "agent could not sign data with requested identity" if agent_failed(type)
  raise AgentError, "bad authentication response #{type}" if type != SSH2_AGENT_SIGN_RESPONSE

  return reply.read_string
end