What are these open ports?
 

nmap shows:
..
3130/udp open squid-ipc
32768/udp open omad

squid is running on 3128/tcp. do I need 3130/udp too?
any ideas what´s the other?

if im not mistaken port 3130 supposed to be icp protocol, not ipc. Squid needs it for contacting it's peer, which means if you wants to configure your squid to "cooperate" with another Squid server, you need this protocol enabled. By default, it is enabled but you can disable it if compiled from source packages.


Some references :-

http://squid.visolve.com/squid/squid24s1/network.htm
http://www.squid-cache.org/Doc/FAQ/FAQ.html