Net::SSH is a library for interacting, programmatically, with remote processes via the SSH2 protocol. Sessions are always initiated via Net::SSH.start. From there, a program interacts with the new SSH session via the convenience methods on Net::SSH::Connection::Session, by opening and interacting with new channels (Net::SSH::Connection:Session#open_channel and Net::SSH::Connection::Channel), or by forwarding local and/or remote ports through the connection (Net::SSH::Service::Forward).
The SSH protocol is very event-oriented. Requests are sent from the client to the server, and are answered asynchronously. This gives great flexibility (since clients can have multiple requests pending at a time), but it also adds complexity. Net::SSH tries to manage this complexity by providing some simpler methods of synchronous communication (see Net::SSH::Connection::Session#exec!).
In general, though, and if you want to do anything more complicated than simply executing commands and capturing their output, you‘ll need to use channels (Net::SSH::Connection::Channel) to build state machines that are executed while the event loop runs (Net::SSH::Connection::Session#loop).
Net::SSH::Connection::Session and Net::SSH::Connection::Channel have more information about this technique.
Net::SSH.start("host", "user", :password => "password") do |ssh|
result = ssh.exec!("ls -l")
puts result
end
Net::SSH.start("host", "user", :password => "password") do |ssh|
ssh.forward.local(1234, "www.google.com", 80)
ssh.loop { true }
end
Net::SSH.start("host", "user", :password => "password") do |ssh|
ssh.forward.remote(80, "www.google.com", 1234)
ssh.loop { true }
end
| Prompt | = | begin require 'highline' | Try to load Highline and Termios in turn, selecting the corresponding PromptMethods module to use. If neither are available, choose PromptMethods::Clear. | |
| VALID_OPTIONS | = | [ :auth_methods, :compression, :compression_level, :config, :encryption, :forward_agent, :hmac, :host_key, :kex, :keys, :languages, :logger, :paranoid, :password, :port, :proxy, :rekey_blocks_limit, :rekey_limit, :rekey_packet_limit, :timeout, :verbose, :global_known_hosts_file, :user_known_hosts_file, :host_key_alias, :host_name, :user, :properties, :passphrase | This is the set of options that Net::SSH.start recognizes. See Net::SSH.start for a description of each option. | |
| Prompt | = | begin require 'highline' | Try to load Highline and Termios in turn, selecting the corresponding PromptMethods module to use. If neither are available, choose PromptMethods::Clear. | |
| VALID_OPTIONS | = | [ :auth_methods, :compression, :compression_level, :config, :encryption, :forward_agent, :hmac, :host_key, :kex, :keys, :languages, :logger, :paranoid, :password, :port, :proxy, :rekey_blocks_limit, :rekey_limit, :rekey_packet_limit, :timeout, :verbose, :global_known_hosts_file, :user_known_hosts_file, :host_key_alias, :host_name, :user, :properties, :passphrase | This is the set of options that Net::SSH.start recognizes. See Net::SSH.start for a description of each option. |
The standard means of starting a new SSH connection. When used with a block, the connection will be closed when the block terminates, otherwise the connection will just be returned. The yielded (or returned) value will be an instance of Net::SSH::Connection::Session (q.v.). (See also Net::SSH::Connection::Channel and Net::SSH::Service::Forward.)
Net::SSH.start("host", "user") do |ssh|
ssh.exec! "cp /some/file /another/location"
hostname = ssh.exec!("hostname")
ssh.open_channel do |ch|
ch.exec "sudo -p 'sudo password: ' ls" do |ch, success|
abort "could not execute sudo ls" unless success
ch.on_data do |ch, data|
print data
if data =~ /sudo password: /
ch.send_data("password\n")
end
end
end
end
ssh.loop
end
This method accepts the following options (all are optional):
# File lib/net/ssh.rb, line 150
150: def self.start(host, user, options={}, &block)
151: invalid_options = options.keys - VALID_OPTIONS
152: if invalid_options.any?
153: raise ArgumentError, "invalid option(s): #{invalid_options.join(', ')}"
154: end
155:
156: files = case options.fetch(:config, true)
157: when true then Net::SSH::Config.default_files
158: when false, nil then []
159: else Array(options[:config])
160: end
161:
162: options = Net::SSH::Config.for(host, files).merge(options)
163: host = options.fetch(:host_name, host)
164:
165: if !options.key?(:logger)
166: options[:logger] = Logger.new(STDERR)
167: options[:logger].level = Logger::FATAL
168: end
169:
170: if options[:verbose]
171: options[:logger].level = case options[:verbose]
172: when Fixnum then options[:verbose]
173: when :debug then Logger::DEBUG
174: when :info then Logger::INFO
175: when :warn then Logger::WARN
176: when :error then Logger::ERROR
177: when :fatal then Logger::FATAL
178: else raise ArgumentError, "can't convert #{options[:verbose].inspect} to any of the Logger level constants"
179: end
180: end
181:
182: transport = Transport::Session.new(host, options)
183: auth = Authentication::Session.new(transport, options)
184:
185: user = options.fetch(:user, user)
186: if auth.authenticate("ssh-connection", user, options[:password])
187: connection = Connection::Session.new(transport, options)
188: if block_given?
189: yield connection
190: connection.close
191: else
192: return connection
193: end
194: else
195: raise AuthenticationFailed, user
196: end
197: end
The standard means of starting a new SSH connection. When used with a block, the connection will be closed when the block terminates, otherwise the connection will just be returned. The yielded (or returned) value will be an instance of Net::SSH::Connection::Session (q.v.). (See also Net::SSH::Connection::Channel and Net::SSH::Service::Forward.)
Net::SSH.start("host", "user") do |ssh|
ssh.exec! "cp /some/file /another/location"
hostname = ssh.exec!("hostname")
ssh.open_channel do |ch|
ch.exec "sudo -p 'sudo password: ' ls" do |ch, success|
abort "could not execute sudo ls" unless success
ch.on_data do |ch, data|
print data
if data =~ /sudo password: /
ch.send_data("password\n")
end
end
end
end
ssh.loop
end
This method accepts the following options (all are optional):
# File lib/net/ssh.rb, line 150
150: def self.start(host, user, options={}, &block)
151: invalid_options = options.keys - VALID_OPTIONS
152: if invalid_options.any?
153: raise ArgumentError, "invalid option(s): #{invalid_options.join(', ')}"
154: end
155:
156: files = case options.fetch(:config, true)
157: when true then Net::SSH::Config.default_files
158: when false, nil then []
159: else Array(options[:config])
160: end
161:
162: options = Net::SSH::Config.for(host, files).merge(options)
163: host = options.fetch(:host_name, host)
164:
165: if !options.key?(:logger)
166: options[:logger] = Logger.new(STDERR)
167: options[:logger].level = Logger::FATAL
168: end
169:
170: if options[:verbose]
171: options[:logger].level = case options[:verbose]
172: when Fixnum then options[:verbose]
173: when :debug then Logger::DEBUG
174: when :info then Logger::INFO
175: when :warn then Logger::WARN
176: when :error then Logger::ERROR
177: when :fatal then Logger::FATAL
178: else raise ArgumentError, "can't convert #{options[:verbose].inspect} to any of the Logger level constants"
179: end
180: end
181:
182: transport = Transport::Session.new(host, options)
183: auth = Authentication::Session.new(transport, options)
184:
185: user = options.fetch(:user, user)
186: if auth.authenticate("ssh-connection", user, options[:password])
187: connection = Connection::Session.new(transport, options)
188: if block_given?
189: yield connection
190: connection.close
191: else
192: return connection
193: end
194: else
195: raise AuthenticationFailed, user
196: end
197: end