Looking through your firewall logs, or the output of a "netstat -a" and notice a connection to a port you are not familar with? And want to impress your friends? Use this cool nerdy trick provided by portsdb.org and trusty ol' nslookup to find port names...
nslookup -q=txt port.protocol.portsdb.org
Where port is the port number you're interested in, and protocol is tcp, or udp. For example, say you spot the following line in your firewall log:
DATE IP TYPE PORT 30/08/04 188.8.131.52 UDP 1433
After you are finished being impressed by the groovy IP address, whack the following down on the command line:
nslookup -q=txt 1433.udp.portsdb.org
Non-authoritative answer: 1433.udp.portsdb.org text = "ms-sql-s"
There you go. Someone trying to send a UDP packet to your SQL server. Hope you're patched up, 'cause it's most likely a Slammer packet.