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
PubKeyAuthentication => maps to the :auth_methods option
RekeyLimit => :rekey_limit
User => :user
UserKnownHostsFile => :user_known_hosts_file
NumberOfPasswordPrompts => :number_of_password_prompts
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.)
# File lib/net/ssh/config.rb, line 54 def default_auth_methods @@default_auth_methods end
Returns an array of locations of OpenSSH configuration files to parse by default.
# File lib/net/ssh/config.rb, line 50 def default_files @@default_files end
Filters ::default_files down to the files that are expandable.
# File lib/net/ssh/config.rb, line 252 def expandable_default_files default_files.keep_if do |path| begin File.expand_path(path) true rescue ArgumentError false end end 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.
# File lib/net/ssh/config.rb, line 62 def for(host, files=expandable_default_files) translate(files.inject({}) { |settings, file| load(file, host, settings) }) 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.)
# File lib/net/ssh/config.rb, line 74 def load(path, host, settings={}) file = File.expand_path(path) base_dir = File.dirname(file) return settings unless File.readable?(file) globals = {} host_matched = false seen_host = 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+$/ then value.to_i when /^no$/ then false when /^yes$/ 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 host_matched = false else host_matched = positive_hosts.any? { |h| host =~ pattern2regex(h) } end seen_host = true settings[key] = host elsif !seen_host 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) end else globals[key] = value unless settings.key?(key) end elsif host_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) end else settings[key] = value unless settings.key?(key) end end end settings = globals.merge(settings) if globals return settings 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.
# File lib/net/ssh/config.rb, line 155 def translate(settings) auth_methods = default_auth_methods.clone (auth_methods << 'challenge-response').uniq! ret = settings.inject({auth_methods: auth_methods}) do |hash, (key, value)| case key when 'bindaddress' then hash[:bind_address] = value 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 'identitiesonly' then hash[:keys_only] = value when 'globalknownhostsfile' hash[:global_known_hosts_file] = value when 'hostbasedauthentication' then if value (hash[:auth_methods] << "hostbased").uniq! else hash[:auth_methods].delete("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.gsub(/%h/, settings['host']) when 'identityfile' then hash[:keys] = value when 'macs' then hash[:hmac] = value.split(/,/) when 'serveralivecountmax' hash[:keepalive_maxcount] = value.to_i if value when 'serveraliveinterval' if value && value.to_i > 0 hash[:keepalive] = true hash[:keepalive_interval] = value.to_i else hash[:keepalive] = false end when 'passwordauthentication' if value (hash[:auth_methods] << 'password').uniq! else hash[:auth_methods].delete('password') end when 'challengeresponseauthentication' if value (hash[:auth_methods] << 'challenge-response').uniq! else hash[:auth_methods].delete('challenge-response') end when 'kbdinteractiveauthentication' if value (hash[:auth_methods] << 'keyboard-interactive').uniq! else hash[:auth_methods].delete('keyboard-interactive') end when 'port' hash[:port] = value when 'preferredauthentications' hash[:auth_methods] = value.split(/,/) # TODO we should place to preferred_auth_methods rather than auth_methods when 'proxycommand' if value and !(value =~ /^none$/) require 'net/ssh/proxy/command' hash[:proxy] = Net::SSH::Proxy::Command.new(value) end when 'pubkeyauthentication' if value (hash[:auth_methods] << 'publickey').uniq! else hash[:auth_methods].delete('publickey') end when 'rekeylimit' hash[:rekey_limit] = interpret_size(value) when 'user' hash[:user] = value when 'userknownhostsfile' hash[:user_known_hosts_file] = value when 'sendenv' multi_send_env = value.to_s.split(/\s+/) hash[:send_env] = multi_send_env.map { |e| Regexp.new pattern2regex(e).source, false } when 'numberofpasswordprompts' hash[:number_of_password_prompts] = value.to_i end hash end merge_challenge_response_with_keyboard_interactive(ret) end
# File lib/net/ssh/config.rb, line 304 def included_file_paths(base_dir, config_path) paths = Dir.glob(File.expand_path(config_path)).select { |f| File.file?(f) } paths += Dir.glob(File.join(base_dir, config_path)).select { |f| File.file?(f) } paths.uniq end
Converts the given size into an integer number of bytes.
# File lib/net/ssh/config.rb, line 287 def interpret_size(size) case size when /k$/ then size.to_i * 1024 when /m$/ then size.to_i * 1024 * 1024 when /g$/ then size.to_i * 1024 * 1024 * 1024 else size.to_i end end
# File lib/net/ssh/config.rb, line 296 def merge_challenge_response_with_keyboard_interactive(hash) if hash[:auth_methods].include?('challenge-response') hash[:auth_methods].delete('challenge-response') (hash[:auth_methods] << 'keyboard-interactive').uniq! end hash end
Converts an ssh_config pattern into a regex for matching against host names.
# File lib/net/ssh/config.rb, line 267 def pattern2regex(pattern) tail = pattern prefix = "" while !tail.empty? do head,sep,tail = tail.partition(/[\*\?]/) prefix = prefix + Regexp.quote(head) case sep when '*' prefix += '.*' when '?' prefix += '.' when '' else fail "Unpexpcted sep:#{sep}" end end Regexp.new("^" + prefix + "$", true) end