mailing list archives
Re: unused bit attack alert
From: Patrick.Mullen () GD-CS COM (Mullen, Patrick)
Date: Tue, 22 Feb 2000 17:15:43 -0500
Fromthe Snort Portscan module
/* Strip off the reserved bits for the testing, but flag
that a scan is being done.
th_flags_cleaned = th_flags & ~(R_RES1 | R_RES2);
if(th_flags != th_flags_cleaned)
scan = sRESERVEDBITS;
This means that anything with reserved bits set are
shown as a portscan. Obviously, later down flags
are checked as normal using th_flags_cleaned and
This code was inspired by connlogd, written by
Alec Kosky, which probably is also immune to this method.