Usually when we admin a network, we need to know what are the protocols used more frequently, and why not, discover if someone are using improper P2P software; so we can use SPAN.
The Switched Port Analyzer (SPAN) feature, which is sometimes called port mirroring or port monitoring, selects network traffic for analysis by a network [...]

The configuration register can be used to change router behavior in several ways, such as:

how the router boots (into ROMmon, NetBoot)
options while booting (ignore configuration, disable boot messages)
console speed (baud rate for a terminal emulation session)

To view the current setting of the configuration register, use the show version command:

Due to the number of CLI commands needed to manually disable services in an attempt to make the router more secure, Cisco introduced the AutoSecure feature from the Major Release 12.3 and subsequent 12.3 T.
AutoSecure is a good command for customers without special Security Operations Applications because it allows them to quickly secure their network [...]