Port knocking

In Computing, port knocking is a method of externally opening port (computing)s on a firewall (networking) by generating a connection attempt on a set of prespecified closed ports. Once a correct sequence of connection attempts is received the firewall rules are dynamically modified to allow the host which sent the connection attempts to connect over specified port(s). This is usually implemented by configuring a daemon (computer software) to watch the firewall log file for said connection attempts then modify the firewall configuration accordingly.

While this technique for securing access to remote network daemons has not yet been widely adopted by the security community, it has been integrated in newer Root kit.

= External links =

*[http://www.portknocking.org/ PORTKNOCKING - A system for stealthy authentication across closed ports.] *[http://www.linuxjournal.com/article/6811 Linux Journal: Port Knocking] *[http://slashdot.org/articles/04/02/05/1834228.shtmltid=126&tid=172 Slashdot Port Knocking For Added Security] *[http://sourceforge.net/projects/winportknocking A Windows implementation of port knocking.] *[http://www.neep.co.uk/tab=Projects&menu=Port%20Knocking A Linux IP Tables implementation of port knocking.]