Class | Net::SSH::Gateway |
In: |
lib/net/ssh/gateway.rb
lib/net/ssh/gateway.rb |
Parent: | Object |
A Gateway is an object that allows you to tunnel network connections through a publicly visible host to a host hidden behind it. This is particularly useful when dealing with hosts behind a firewall. One host will generally be visible (and accessible) outside the firewall, while the others will all be behind the firewall, and the only way to access those restricted hosts is by first logging into the publicly visible host, and from thence logging into the restricted ones.
This class makes it easy to programmatically connect to these restricted hosts via SSH. You can either simply forward a port from the local host to the remote host, or you can open a new Net::SSH connection to the remote host via a forwarded port.
require 'net/ssh/gateway' gateway = Net::SSH::Gateway.new('host.name', 'user') gateway.open('hidden.host', 80) do |port| Net::HTTP.get_print '127.0.0.1', '/path', port end gateway.ssh('hidden.host', 'user') do |ssh| puts ssh.exec!("hostname") end gateway.shutdown!
Port numbers are allocated automatically, beginning at MAX_PORT and decrementing on each request for a new port until MIN_PORT is reached. If a port is already in use, this is detected and a different port will be assigned.
MAX_PORT | = | 65535 | The maximum port number that the gateway will attempt to use to forward connections from. | |
MIN_PORT | = | 1024 | The minimum port number that the gateway will attempt to use to forward connections from. | |
MAX_PORT | = | 65535 | The maximum port number that the gateway will attempt to use to forward connections from. | |
MIN_PORT | = | 1024 | The minimum port number that the gateway will attempt to use to forward connections from. |
Instantiate a new Gateway object, using the given remote host as the tunnel. The arguments here are identical to those for Net::SSH.start, and are passed as given to that method to start up the gateway connection.
gateway = Net::SSH::Gateway.new('host', 'user', :password => "password")
As of 1.1 there is an additional option to specify the wait time for the gateway thread. The default is 0.001 seconds and can be changed with the :loop_wait option.
# File lib/net/ssh/gateway.rb, line 73 73: def initialize(host, user, options={}) 74: @session = Net::SSH.start(host, user, options) 75: @session_mutex = Mutex.new 76: @port_mutex = Mutex.new 77: @next_port = MAX_PORT 78: @loop_wait = options.delete(:loop_wait) || 0.001 79: initiate_event_loop! 80: end
Instantiate a new Gateway object, using the given remote host as the tunnel. The arguments here are identical to those for Net::SSH.start, and are passed as given to that method to start up the gateway connection.
gateway = Net::SSH::Gateway.new('host', 'user', :password => "password")
As of 1.1 there is an additional option to specify the wait time for the gateway thread. The default is 0.001 seconds and can be changed with the :loop_wait option.
# File lib/net/ssh/gateway.rb, line 73 73: def initialize(host, user, options={}) 74: @session = Net::SSH.start(host, user, options) 75: @session_mutex = Mutex.new 76: @port_mutex = Mutex.new 77: @next_port = MAX_PORT 78: @loop_wait = options.delete(:loop_wait) || 0.001 79: initiate_event_loop! 80: end
Opens a new port on the local host and forwards it to the given host/port via the gateway host. If a block is given, the newly allocated port number will be yielded to the block, and the port automatically closed (see close) when the block finishes. Otherwise, the port number will be returned, and the caller is responsible for closing the port (close).
gateway.open('host', 80) do |port| # ... end port = gateway.open('host', 80) # ... gateway.close(port)
If local_port is not specified, the next available port will be used.
# File lib/net/ssh/gateway.rb, line 121 121: def open(host, port, local_port=nil) 122: ensure_open! 123: 124: actual_local_port = local_port || next_port 125: 126: @session_mutex.synchronize do 127: @session.forward.local(actual_local_port, host, port) 128: end 129: 130: if block_given? 131: begin 132: yield actual_local_port 133: ensure 134: close(actual_local_port) 135: end 136: else 137: return actual_local_port 138: end 139: rescue Errno::EADDRINUSE 140: raise if local_port # if a local port was explicitly requested, bubble the error up 141: retry 142: end
Opens a new port on the local host and forwards it to the given host/port via the gateway host. If a block is given, the newly allocated port number will be yielded to the block, and the port automatically closed (see close) when the block finishes. Otherwise, the port number will be returned, and the caller is responsible for closing the port (close).
gateway.open('host', 80) do |port| # ... end port = gateway.open('host', 80) # ... gateway.close(port)
If local_port is not specified, the next available port will be used.
# File lib/net/ssh/gateway.rb, line 121 121: def open(host, port, local_port=nil) 122: ensure_open! 123: 124: actual_local_port = local_port || next_port 125: 126: @session_mutex.synchronize do 127: @session.forward.local(actual_local_port, host, port) 128: end 129: 130: if block_given? 131: begin 132: yield actual_local_port 133: ensure 134: close(actual_local_port) 135: end 136: else 137: return actual_local_port 138: end 139: rescue Errno::EADDRINUSE 140: raise if local_port # if a local port was explicitly requested, bubble the error up 141: retry 142: end
Shuts down the gateway by closing all forwarded ports and then closing the gateway‘s SSH session.
# File lib/net/ssh/gateway.rb, line 90 90: def shutdown! 91: return unless active? 92: 93: @session_mutex.synchronize do 94: # cancel all active forward channels 95: @session.forward.active_locals.each do |lport, host, port| 96: @session.forward.cancel_local(lport) 97: end 98: end 99: 100: @active = false 101: 102: @thread.join 103: @session.close 104: end
Shuts down the gateway by closing all forwarded ports and then closing the gateway‘s SSH session.
# File lib/net/ssh/gateway.rb, line 90 90: def shutdown! 91: return unless active? 92: 93: @session_mutex.synchronize do 94: # cancel all active forward channels 95: @session.forward.active_locals.each do |lport, host, port| 96: @session.forward.cancel_local(lport) 97: end 98: end 99: 100: @active = false 101: 102: @thread.join 103: @session.close 104: end
Forwards a new connection to the given host and opens a new Net::SSH connection to that host over the forwarded port. If a block is given, the new SSH connection will be yielded to the block, and autoclosed when the block terminates. The forwarded port will be autoclosed as well. If no block was given, the new SSH connection will be returned, and it is up to the caller to terminate both the connection and the forwarded port when done.
gateway.ssh('host', 'user') do |ssh| # ... end ssh = gateway.ssh('host', 'user') # ... ssh.close gateway.close(ssh.transport.port)
# File lib/net/ssh/gateway.rb, line 170 170: def ssh(host, user, options={}, &block) 171: local_port = open(host, options[:port] || 22) 172: 173: begin 174: Net::SSH.start("127.0.0.1", user, options.merge(:port => local_port), &block) 175: ensure 176: close(local_port) if block || $! 177: end 178: end
Forwards a new connection to the given host and opens a new Net::SSH connection to that host over the forwarded port. If a block is given, the new SSH connection will be yielded to the block, and autoclosed when the block terminates. The forwarded port will be autoclosed as well. If no block was given, the new SSH connection will be returned, and it is up to the caller to terminate both the connection and the forwarded port when done.
gateway.ssh('host', 'user') do |ssh| # ... end ssh = gateway.ssh('host', 'user') # ... ssh.close gateway.close(ssh.transport.port)
# File lib/net/ssh/gateway.rb, line 170 170: def ssh(host, user, options={}, &block) 171: local_port = open(host, options[:port] || 22) 172: 173: begin 174: Net::SSH.start("127.0.0.1", user, options.merge(:port => local_port), &block) 175: ensure 176: close(local_port) if block || $! 177: end 178: end