Who knows ICMP programming ?

I need some help on ICMP programming , on how to signal errors to connections [in order to break them] !
How do you use the ICMP and IP header and some help or tutorials ...
Thanks !

http://www.cyberport.com/~tangent/pr...tutorials.html

http://www.vijaymukhi.com/vmis/wsock.htm

http://world.std.com/~jimf/papers/sockets/winsock.html

http://www.vijaymukhi.com/vmis/vmchap4.htm

also, run a google search on "winsock" (it's winsock, not ICMP programming )

i want to learn to work with raw socket and ip or icmp headers !
more advanced stuff

i found what i needed ! thx 10x