Chris Bunch Chris Bunch - 4 months ago 18
Ruby Question

Ruby - See if a port is open

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

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