Question

I need a quick way to find out if a given port is open with Ruby. I currently am fiddling around with this:

require 'socket'  def is_port_open?(ip, port)   begin     TCPSocket.new(ip, port)   rescue Errno::ECONNREFUSED     return false   end   return true end 

It works great if the port is open, but the downside of this is that occasionally it will just sit and wait for 10-20 seconds and then eventually time out, throwing a ETIMEOUT exception (if the port is closed). My question is thus:

Can this code be amended to only wait for a second (and return false if we get nothing back by then) or is there a better way to check if a given port is open on a given host?

Edit: Calling bash code is acceptable also as long as it works cross-platform (e.g., Mac OS X, *nix, and Cygwin), although I do prefer Ruby code.

Answer 1

Something like the following might work:

require 'socket' require 'timeout'  def is_port_open?(ip, port)   begin     Timeout::timeout(1) do       begin         s = TCPSocket.new(ip, port)         s.close         return true       rescue Errno::ECONNREFUSED, Errno::EHOSTUNREACH         return false       end     end   rescue Timeout::Error   end    return false end