Re: [Snort-users] Port Negation not working?

Hello Paul,

Since the rule is an 'ip' rule, the port is insignificant.


Todd

Paul Melson wrote:
> Because of a high number of false positives caused by MIME-encoded file
> attachments, I have modified most of the shellcode/nop rules on one of our
> sensors so that they should ignore SMTP traffic.  However, I have a handful
> of rules that still fire on SMTP traffic.  Here's one example.
>
> Original rule:
> alert ip $EXTERNAL_NET any -> $HOME_NET any (msg:"SHELLCODE base64 x86
> NOOP"; \
> content:"RERERERERERERERERERERERERERERERER"; metadata:policy security-ips
> drop; \
> classtype:shellcode-detect; sid:12801; rev:1;)
>
> Modified rule:
> alert ip $EXTERNAL_NET any -> $HOME_NET !25 (msg:"SHELLCODE base64 x86
> NOOP"; \
> content:"RERERERERERERERERERERERERERERERER"; metadata:policy security-ips
> drop; \
> classtype:shellcode-detect; sid:12801; rev:1;)
>
> I still get alerts from the modified rule for SMTP traffic containing the
> "RERERE..." string.  I know that the rule/port syntax has been modified in
> 2.8 to allow port lists, but according to the manual[1], this syntax should
> still work for port negation.  Am I missing something?
>
> Thanks,
> PaulM
>
> [1] http://www.snort.org/docs/snort_htmanuals/htmanual_280/node169.html
>
>
>
>
> -------------------------------------------------------------------------
> This SF.net email is sponsored by: Microsoft
> Defy all challenges. Microsoft(R) Visual Studio 2005.
> http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/
> _______________________________________________
> Snort-users mailing list
> Snort-users@lists.sourceforge.net
> Go to this URL to change user options or unsubscribe:
> https://lists.sourceforge.net/lists/listinfo/snort-users
> Snort-users list archive:
> http://www.geocrawler.com/redir-sf.php3?list=snort-users


-------------------------------------------------------------------------
This SF.net email is sponsored by: Microsoft
Defy all challenges. Microsoft(R) Visual Studio 2005.
http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/
_______________________________________________
Snort-users mailing list
Snort-users@lists.sourceforge.net
Go to this URL to change user options or unsubscribe:
https://lists.sourceforge.net/lists/listinfo/snort-users
Snort-users list archive:
http://www.geocrawler.com/redir-sf.php3?list=snort-users