IOS Zone Based Firewall

One of the most commonly covered security features when it comes to Cisco security is the ZBF.  It wouldn't be much of a network security blog without at least one post on this topic, so here's my take. With IOS version 12.4(6)T, Cisco introduced the Zone Based Firewall (ZBF), sometimes referred to as the Zone Policy Based Firewall.  With this, the Classic IOS Firewall or Context-Based...

TCL Scripting

According to it's man page, "tclsh is a shell-like application that reads TCL commands from its standard input or from a file and evaluates them. If invoked with no arguments then it runs interactively, reading TCL commands from standard input and printing command results and error messages to standard output. It runs until the exit command is invoked or until it reaches end-of-file on its standard...