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:
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ChallengeResponseAuthentication => maps to the :auth_methods option challenge-response (then coleasced into keyboard-interactive)
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KbdInteractiveAuthentication => maps to the :auth_methods keyboard-interactive
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Ciphers => maps to the :encryption option
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Compression => :compression
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CompressionLevel => :compression_level
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ConnectTimeout => maps to the :timeout option
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ForwardAgent => :forward_agent
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GlobalKnownHostsFile => :global_known_hosts_file
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HostBasedAuthentication => maps to the :auth_methods option
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HostKeyAlgorithms => maps to :host_key option
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HostKeyAlias => :host_key_alias
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HostName => :host_name
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IdentityFile => maps to the :keys option
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IdentityAgent => :identity_agent
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IdentitiesOnly => :keys_only
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Macs => maps to the :hmac option
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PasswordAuthentication => maps to the :auth_methods option password
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Port => :port
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PreferredAuthentications => maps to the :auth_methods option
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ProxyCommand => maps to the :proxy option
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ProxyJump => maps to the :proxy option
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PubKeyAuthentication => maps to the :auth_methods option
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RekeyLimit => :rekey_limit
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User => :user
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UserKnownHostsFile => :user_known_hosts_file
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NumberOfPasswordPrompts => :number_of_password_prompts
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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
# File lib/net/ssh/config.rb, line 58 def default_auth_methods @@default_auth_methods.clone end
Returns an array of locations of OpenSSH configuration files to parse by default.
# File lib/net/ssh/config.rb, line 54 def default_files @@default_files.clone end
Filters ::default_files down to the files that are expandable.
# File lib/net/ssh/config.rb, line 177 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 66 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 78 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, $2 else key, value = line.strip.split(/\s+/, 2) end # silently ignore malformed entries next if value.nil? key.downcase! value = unquote(value) value = case value.strip when /^\d+$/ 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
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 167 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
Private Class Methods
# File lib/net/ssh/config.rb, line 330 def eval_match_conditions(condition, host, settings) # Not using `\s` for whitespace matching as canonical # ssh_config parser implementation (OpenSSH) has specific character set. # Ref: https://github.com/openssh/openssh-portable/blob/2581333d564d8697837729b3d07d45738eaf5a54/misc.c#L237-L239 conditions = condition.split(/[ \t\r\n]+|(?<!=)=(?!=)/).reject(&:empty?) return true if conditions == ["all"] conditions = conditions.each_slice(2) condition_matches = [] conditions.each do |(kind,exprs)| exprs = unquote(exprs) case kind.downcase when "all" raise "all cannot be mixed with other conditions" when "host" if exprs.start_with?('!') negated = true exprs = exprs[1..-1] else negated = false end condition_met = false exprs.split(",").each do |expr| condition_met = condition_met || host =~ pattern2regex(expr) end condition_matches << (true && negated ^ condition_met) # else # warn "net-ssh: Unsupported expr in Match block: #{kind}" end end !condition_matches.empty? && condition_matches.all? end
# File lib/net/ssh/config.rb, line 318 def included_file_paths(base_dir, config_paths) tokenize_config_value(config_paths).flat_map do |path| Dir.glob(File.expand_path(path, base_dir)).select { |f| File.file?(f) } end end
Converts the given size into an integer number of bytes.
# File lib/net/ssh/config.rb, line 301 def interpret_size(size) case size when /k$/i then size.to_i * 1024 when /m$/i then size.to_i * 1024 * 1024 when /g$/i then size.to_i * 1024 * 1024 * 1024 else size.to_i end end
# File lib/net/ssh/config.rb, line 310 def merge_challenge_response_with_keyboard_interactive(hash) if hash[:auth_methods].include?('challenge-response') hash[:auth_methods].delete('challenge-response') (hash[:auth_methods] << 'keyboard-interactive').uniq! end hash end
Converts an ssh_config pattern into a regex for matching against host names.
# File lib/net/ssh/config.rb, line 281 def pattern2regex(pattern) tail = pattern prefix = "" while !tail.empty? do head,sep,tail = tail.partition(/[\*\?]/) prefix = prefix + Regexp.quote(head) case sep when '*' prefix += '.*' when '?' prefix += '.' when '' else fail "Unpexpcted sep:#{sep}" end end Regexp.new("^" + prefix + "$", true) end
Tokenize string into tokens. A token is a word or a quoted sequence of words, separated by whitespaces.
# File lib/net/ssh/config.rb, line 326 def tokenize_config_value(str) str.scan(/([^"\s]+)?(?:"([^"]+)")?\s*/).map(&:join) end
# File lib/net/ssh/config.rb, line 190 def translate_config_key(hash, key, value, settings) rename = { bindaddress: :bind_address, compression: :compression, compressionlevel: :compression_level, connecttimeout: :timeout, forwardagent: :forward_agent, identitiesonly: :keys_only, identityagent: :identity_agent, globalknownhostsfile: :global_known_hosts_file, hostkeyalias: :host_key_alias, identityfile: :keys, fingerprinthash: :fingerprint_hash, port: :port, user: :user, userknownhostsfile: :user_known_hosts_file } case key when :ciphers hash[:encryption] = value.split(/,/) when :hostbasedauthentication if value (hash[:auth_methods] << "hostbased").uniq! else hash[:auth_methods].delete("hostbased") end when :hostkeyalgorithms hash[:host_key] = value.split(/,/) when :hostname hash[:host_name] = value.gsub(/%h/, settings['host']) when :macs 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 :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$/ require 'net/ssh/proxy/command' hash[:proxy] = Net::SSH::Proxy::Command.new(value) end when :proxyjump if value require 'net/ssh/proxy/jump' hash[:proxy] = Net::SSH::Proxy::Jump.new(value) end when :pubkeyauthentication if value (hash[:auth_methods] << 'publickey').uniq! else hash[:auth_methods].delete('publickey') end when :rekeylimit hash[:rekey_limit] = interpret_size(value) when :sendenv multi_send_env = value.to_s.split(/\s+/) hash[:send_env] = multi_send_env.map { |e| Regexp.new pattern2regex(e).source, false } when :numberofpasswordprompts hash[:number_of_password_prompts] = value.to_i when *rename.keys hash[rename[key]] = value end end
# File lib/net/ssh/config.rb, line 365 def unquote(string) string =~ /^"(.*)"$/ ? Regexp.last_match(1) : string end