I want to deny a particular malicious UDP packet. I can readily identify this packet from the rest by looking at the data section, where data offset 2 is 0xaa, data[5] is 0xbb, etc. Are there any tools or code samples that can do this?

Basically, instead of seeing the packet in the following tcpdump, I want to block it. I started to write a proxy but realized I would need to keep sessions and that's a nightmare. Is there an easier way to do this? The firewalls I've seen only block based on port, not on data payload.


tcpdump -i eth1 udp[2:1] = 0xaa and udp[5:2] = 0xbbcc