Corporate policies prohibit the unauthorized connection of hardware to the company network, threatening dire consequences in the case of non-compliance. Fair enough, but how do you actually go about catching somebody trying to plug an illegal laptop into your Ethernet?

A touchy LAN that plays like a movie diva can spoil any admin’s day. Ethtool to the rescue!

If you need a tool for filtering protocols that doesn’t depend on the port, try L7, an IPTables patch that operates through regular expressions.

It is quite easy to take a TCP connection down using a RST attack, and this risk increases with applications that need long-term connections, such as VPNs, DNS zone transfers, and BGP. We’ll describe how a TCP attack can happen, and we’ll show you some simple techniques for protecting your network.

If you do not receive a response to a ping, or if the response is seriously delayed, you might like to take this as a warning. But who wants to ping all day? You need a ping-based monitoring utility like Smokeping.