class Net::SSH::Config

The Net::SSH::Config class is used to parse OpenSSH configuration files, and translates that syntax into the configuration syntax that Net::SSH understands. This lets Net::SSH scripts read their configuration (to some extent) from OpenSSH configuration files (~/.ssh/config, /etc/ssh_config, and so forth).

Only a subset of OpenSSH configuration options are understood:

ChallengeResponseAuthentication => maps to the :auth_methods option challenge-response (then coleasced into keyboard-interactive)
KbdInteractiveAuthentication => maps to the :auth_methods keyboard-interactive
Ciphers => maps to the :encryption option
Compression => :compression
CompressionLevel => :compression_level
ConnectTimeout => maps to the :timeout option
ForwardAgent => :forward_agent
GlobalKnownHostsFile => :global_known_hosts_file
HostBasedAuthentication => maps to the :auth_methods option
HostKeyAlgorithms => maps to :host_key option
HostKeyAlias => :host_key_alias
HostName => :host_name
IdentityFile => maps to the :keys option
IdentitiesOnly => :keys_only
Macs => maps to the :hmac option
PasswordAuthentication => maps to the :auth_methods option password
Port => :port
PreferredAuthentications => maps to the :auth_methods option
ProxyCommand => maps to the :proxy option
ProxyJump => maps to the :proxy option
PubKeyAuthentication => maps to the :auth_methods option
RekeyLimit => :rekey_limit
User => :user
UserKnownHostsFile => :user_known_hosts_file
NumberOfPasswordPrompts => :number_of_password_prompts
FingerprintHash => :fingerprint_hash

Note that you will never need to use this class directly–you can control whether the OpenSSH configuration files are read by passing the :config option to Net::SSH.start. (They are, by default.)

Public Class Methods

default_auth_methods ()

Source

# File lib/net/ssh/config.rb, line 57
def default_auth_methods
  @@default_auth_methods.clone
end

default_files ()

Source

# File lib/net/ssh/config.rb, line 53
def default_files
  @@default_files.clone
end

Returns an array of locations of OpenSSH configuration files to parse by default.

expandable_default_files ()

Source

# File lib/net/ssh/config.rb, line 176
def expandable_default_files
  default_files.keep_if do |path|
    begin
      File.expand_path(path)
      true
    rescue ArgumentError
      false
    end
  end
end

Filters default_files down to the files that are expandable.

for (host, files=expandable_default_files)

Source

# File lib/net/ssh/config.rb, line 65
def for(host, files=expandable_default_files)
  translate(files.inject({}) { |settings, file|
    load(file, host, settings)
  })
end

Loads the configuration data for the given host from all of the given files (defaulting to the list of files returned by default_files), translates the resulting hash into the options recognized by Net::SSH, and returns them.

load (path, host, settings={}, base_dir = nil)

Source

# File lib/net/ssh/config.rb, line 77
def load(path, host, settings={}, base_dir = nil)
  file = File.expand_path(path)
  base_dir ||= File.dirname(file)
  return settings unless File.readable?(file)

  globals = {}
  block_matched = false
  block_seen = false
  IO.foreach(file) do |line|
    next if line =~ /^\s*(?:#.*)?$/

    if line =~ /^\s*(\S+)\s*=(.*)$/
      key, value = $1, $2
    else
      key, value = line.strip.split(/\s+/, 2)
    end

    # silently ignore malformed entries
    next if value.nil?

    key.downcase!
    value = $1 if value =~ /^"(.*)"$/

    value = case value.strip
            when /^\d+$/ then value.to_i
            when /^no$/i then false
            when /^yes$/i then true
            else value
            end

    if key == 'host'
      # Support "Host host1 host2 hostN".
      # See http://github.com/net-ssh/net-ssh/issues#issue/6
      negative_hosts, positive_hosts = value.to_s.split(/\s+/).partition { |h| h.start_with?('!') }

      # Check for negative patterns first. If the host matches, that overrules any other positive match.
      # The host substring code is used to strip out the starting "!" so the regexp will be correct.
      negative_matched = negative_hosts.any? { |h| host =~ pattern2regex(h[1..-1]) }

      if negative_matched
        block_matched = false
      else
        block_matched = positive_hosts.any? { |h| host =~ pattern2regex(h) }
      end

      block_seen = true
      settings[key] = host
    elsif key == 'match'
      block_matched = eval_match_conditions(value, host, settings)
      block_seen = true
    elsif !block_seen
      case key
      when 'identityfile'
        (globals[key] ||= []) << value
      when 'include'
        included_file_paths(base_dir, value).each do |file_path|
          globals = load(file_path, host, globals, base_dir)
        end
      else
        globals[key] = value unless settings.key?(key)
      end
    elsif block_matched
      case key
      when 'identityfile'
        (settings[key] ||= []) << value
      when 'include'
        included_file_paths(base_dir, value).each do |file_path|
          settings = load(file_path, host, settings, base_dir)
        end
      else
        settings[key] = value unless settings.key?(key)
      end
    end
  end

  globals.merge(settings) do |key, oldval, newval|
    case key
    when 'identityfile'
      oldval + newval
    else
      newval
    end
  end
end

Load the OpenSSH configuration settings in the given file for the given host. If settings is given, the options are merged into that hash, with existing values taking precedence over newly parsed ones. Returns a hash containing the OpenSSH options. (See translate for how to convert the OpenSSH options into Net::SSH options.)

translate (settings)

Source

# File lib/net/ssh/config.rb, line 166
def translate(settings)
  auth_methods = default_auth_methods.clone
  (auth_methods << 'challenge-response').uniq!
  ret = settings.each_with_object({ auth_methods: auth_methods }) do |(key, value), hash|
    translate_config_key(hash, key.to_sym, value, settings)
  end
  merge_challenge_response_with_keyboard_interactive(ret)
end

Given a hash of OpenSSH configuration options, converts them into a hash of Net::SSH options. Unrecognized options are ignored. The settings hash must have Strings for keys, all downcased, and the returned hash will have Symbols for keys.