Snort mailing list archives
Does 'ttl' allow less-than-or-equal and greater-than-or-equal?
From: Joshua.Kinard () us-cert gov
Date: Mon, 30 Aug 2010 20:33:33 -0500
Hi -devel, Curious question, but does the 'ttl' rule option support the <= and >= operators? SourceFire's manual indicates that it does (Looking at Sourcefire 3D System Analyst Guide, 4.9.1, Page 1204). The Snort manual is not at all clear, stating in just one line: ttl:[[<number>-]><=]<number>; The single '=' in there seems to suggest that <= and >= are possible, but the parser in src/detection-plugins/sp_ttl_check.c:218 (snort-2.8.6) suggests only that less-than, greater-than, and equals are supported. The switch statement does not set ds_ptr->oper to a constant that would indicate lte/gte operations, nor does it bitwise AND TTL_CHECK_EQ to either TTL_CHECK_GT or TTL_CHECK_LT to achieve a similar effect. If 'ttl' does not support <= or >=, then what is the purpose of the '=' for? Would that not make 'ttl:64;' equivalent to 'ttl:=64;'? Or is this a holdover from an earlier version of Snort that required the '=' character to represent equality? Thanks!, --J ------------------------------------------------------------------------------ This SF.net Dev2Dev email is sponsored by: Show off your parallel programming skills. Enter the Intel(R) Threading Challenge 2010. http://p.sf.net/sfu/intel-thread-sfd _______________________________________________ Snort-devel mailing list Snort-devel () lists sourceforge net https://lists.sourceforge.net/lists/listinfo/snort-devel
Current thread:
- Does 'ttl' allow less-than-or-equal and greater-than-or-equal? Joshua . Kinard (Aug 30)
- Re: Does 'ttl' allow less-than-or-equal and greater-than-or-equal? Russ Combs (Aug 31)
- Message not available
- Re: Does 'ttl' allow less-than-or-equal and greater-than-or-equal? Russ Combs (Sep 02)
- Re: Does 'ttl' allow less-than-or-equal and greater-than-or-equal? Joshua . Kinard (Sep 02)
- Message not available
- Re: Does 'ttl' allow less-than-or-equal and greater-than-or-equal? Russ Combs (Aug 31)