Class: Net::SSH::Config

Inherits:
Object
  • Object
show all
Defined in:
lib/net/ssh/config.rb

Overview

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:

  • 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

  • Macs => maps to the :hmac option

  • PasswordAuthentication => maps to the :auth_methods option

  • Port => :port

  • PreferredAuthentications => maps to the :auth_methods option

  • RekeyLimit => :rekey_limit

  • User => :user

  • UserKnownHostsFile => :user_known_hosts_file

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.)

Constant Summary collapse

@@default_files = 
%w(~/.ssh/config /etc/ssh_config /etc/ssh/ssh_config)

Class Method Summary collapse

Class Method Details

.default_files ⇒ Object

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



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# File 'lib/net/ssh/config.rb', line 39

def default_files
  @@default_files
end

.for(host, files = default_files) ⇒ Object

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.



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# File 'lib/net/ssh/config.rb', line 47

def for(host, files=default_files)
  translate(files.inject({}) { |settings, file| load(file, host, settings) })
end

.load(file, host, settings = {}) ⇒ Object

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.)



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# File 'lib/net/ssh/config.rb', line 57

def load(file, host, settings={})
  file = File.expand_path(file)
  return settings unless File.readable?(file)
  
  matched_host = nil
  multi_host = []
  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
      multi_host = value.split(/,\s+/)
      matched_host = multi_host.select { |h| host =~ pattern2regex(h) }.first
    elsif !matched_host.nil?
      if key == 'identityfile'
        settings[key] ||= []
        settings[key] << value
      else
        settings[key] = value unless settings.key?(key)
      end
    end
  end
  
  return settings
end

.translate(settings) ⇒ Object

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.



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# File 'lib/net/ssh/config.rb', line 107

def translate(settings)
  settings.inject({}) do |hash, (key, value)|
    case key
    when 'ciphers' then
      hash[:encryption] = value.split(/,/)
    when 'compression' then
      hash[:compression] = value
    when 'compressionlevel' then
      hash[:compression_level] = value
    when 'connecttimeout' then
      hash[:timeout] = value
    when 'forwardagent' then
      hash[:forward_agent] = value
    when 'globalknownhostsfile'
      hash[:global_known_hosts_file] = value
    when 'hostbasedauthentication' then
      if value
        hash[:auth_methods] ||= []
        hash[:auth_methods] << "hostbased"
      end
    when 'hostkeyalgorithms' then
      hash[:host_key] = value.split(/,/)
    when 'hostkeyalias' then
      hash[:host_key_alias] = value
    when 'hostname' then
      hash[:host_name] = value
    when 'identityfile' then
      hash[:keys] = value
    when 'macs' then
      hash[:hmac] = value.split(/,/)
    when 'passwordauthentication'
      if value
        hash[:auth_methods] ||= []
        hash[:auth_methods] << "password"
      end
    when 'port'
      hash[:port] = value
    when 'preferredauthentications'
      hash[:auth_methods] = value.split(/,/)
    when 'pubkeyauthentication'
      if value
        hash[:auth_methods] ||= []
        hash[:auth_methods] << "publickey"
      end
    when 'rekeylimit'
      hash[:rekey_limit] = interpret_size(value)
    when 'user'
      hash[:user] = value
    when 'userknownhostsfile'
      hash[:user_known_hosts_file] = value
    end
    hash
  end
end