[Snort-devel] Port Matching Logic

snort user snort.user at ...2499...
Mon Nov 3 14:22:56 EST 2008

Hello and greetings!

If a portvar definition has conflicting meaning, for example -

portvar HTTP_PORTS [80,!0:1024]
alert tcp any any -> any $HTTP_PORTS (............);

If a TCP packet has destination port 80, then should it match or not ?

80 says the packet should match
!0:1024 says it should not match

In snort 2.8 this results in a mismatch.

Should such inconsistencies be caught during rule parsing?
or be left to the rule writer to avoid?

The thing is sometimes it maybe confusing and so hard to avoid.


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