Determine what service listening on port

[redhat at buglecreek.com]

I have a RHEL ES3 server that has three listening udp ports open.  I'm
having a hard time trying to determine what service opened them up.  The
ports are udp 1020,1022,1023.  I have tried to following: "netstat -lp",
 the PID/Program name column just shows a -,  "fuser -n udp 1020",
nothing returned, lsof -i :1020. nothing returned.  I have shut down a
few services in an attempt to discover who opened the ports, but no
luck.  Anything I may have forgotten?

Thanks