I tried looping with
netstat and but the packets are small and not frequent so do not get caught (can still see them with
tcpdump). Need to know which process sends those packets.
tcpdump for the source port number of the packets. Then run
sudo netstat -a -u -n --program
Look for the
PID/Program name matching the source port number.
This assumes that the sending process is leaving its socket open between sends, which is what any normal program would do. If you are dealing a program that is deliberately trying to hide itself, that's whole different story.
I guess it should be possible with
QUEUE target in
iptables. But you'd need to write an userspace application to "check" those packets (and this appication could help you to know which process sends those packets). Sorry, I haven't got more details.