What to expect when controlling router configuration from a remote program

If you're writing software to manage or alter a network, one task you may need to do is to programmatically alter router configurations or enable and disable ports, using a remote connection. This may seem like a difficult problem. However, there's a special extension of the Tcl scripting language that you can use for this purpose, called Expect. Expect can automate telnet, ssh, and other command-line network protocols to manage remote routers and servers. Expect scripts are also useful for the initial configuration of routers, as they don't rely on SNMP already being enabled.