this is obsolete doc -- see http://doc.nethence.com/ instead

TCP/IP notes 

IP Calculations 

nmap may help to find out the IPs concerned by e.g. /24, 

nmap -sL 10.0.0.0/24

Network troubbleshooting 

tcpdump -i eth0 src 10.1.0.16

tcpdump -i eth0 src 10.1.0.16 -X -s 2000

A few links 

http://www.shunsoft.net/ipcalc/help/ 

http://documentation.dedibox.fr/doku.php?id=gestion:ip-sup