shutting down computers through network port

From: Raghul (raghulj_at_gmail.com)
Date: 07/29/05 

Date: 29 Jul 2005 04:27:03 -0700

Hi
  Is it possible to shutdown a machine using port? What I need is I
want to shutdown a machine through port. The machine may be of any kind
of operating system.

Thanx in advance