[Bro] Signtaure Match for TCP packets.

Jaya Dhanesh dhanesh at tataelxsi.co.in
Tue Nov 6 20:26:13 PST 2007


Hi,

I have problems in signature matching. I have a signature like:

signature tcp_http {
	dst-port == 80
	event "HTTP Packet"
}

This should match all packets sent to port 80 including the handshake
packets. But no match was happening when I sent HTTP traffic.

In RuleMatcher::InitEndpoint, the DO_MATCH_OR is called only if 'ip' (IP_Hdr
*ip) is not NULL. For a TCP packet, the
PIA_TCP::DeliverStream calls DoMatch with ip set to 0. This makes sure that
the match doesn't happen for TCP packets with signatures only with
destination ports. Is there any reason for passing a NULL as the last
parameter for DoMatch?


Thanks,
Dhanesh.


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