server work but cannot connect on wit my friend

[jerome]

ok , hello

i have creat one server.
I can connect to my server on my computer but my friend cannot connect to my server
we live at the same town
we have the same internet provider and i have one adsl connection with IP static
we can connect to another server , can speak but my friend cannot connect to my server
we live at 2 kilometer betwenn....
can somebody say to me one information about this probleme ! ?
Thanks a lot

Jerome:(

[Dummer Sack]

What system is running on the server (windows/linux/freebsd)?
Any firewalls running?
A router that is doing NAT?
A port filter on the router?
Do you use windows internet connection scharing or something similar?

What does netstat -nult (linux) or netstat -na (windows) say?