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Re: Pass rules - no effect/not working
From: Jeremy Hoel <jthoel () gmail com>
Date: Sun, 27 Jan 2013 02:29:38 -0700

There is a config option which controls the order how things work..
'config order'

What order are you running?

# cat /var/log/messages | grep snort | grep order
Mar 27 20:28:45 my_machine snort[1659]: Rule application order: ->activation-
dynamic->pass->drop->alert->log

If alert is before pass that could be a problem.

Check that and then we can look at some other things..





On Sat, Jan 26, 2013 at 1:53 AM, Ward Sladek <wsladekjr () hotmail com> wrote:
I have several pass rules in which I continue to get alerts for and need
some help figuring out why...  Some of them are very basic rules, just
host/port -> host/port.

I'm running Snort version 2.9.4 GRE (Build 40) on CentOS 6.3 and here is my
rule order config:
config order: pass activation dynamic drop sdrop reject alert log

Sample pass rules that are not working:
pass tcp 10.16.135.95 947 -> 10.16.135.2 2049 (msg:"LOCAL NFS traffic due to
Xen Storage Repository"; classtype:pass-rule; sid:1000; rev:2;)
pass tcp 10.16.135.2 2049 -> 10.16.135.95 947 (msg:"LOCAL NFS traffic due to
Xen Storage Repository"; classtype:pass-rule; sid:1001; rev:2;)


And the alerts that should not be triggering:
Jan 26 02:00:09 dev01 snort[34315]: [1:1394:14] INDICATOR-SHELLCODE x86 inc
ecx NOOP [Classification: Executable code was detected] [Priority: 2] {TCP}
10.16.135.95:947 -> 10.16.135.2:2049
Jan 25 23:03:43 dev01 snort[20698]: [1:2000428:10] ET POLICY ZIP file
download [Classification: Misc activity] [Priority: 3] {TCP}
10.16.135.2:2049 -> 10.16.135.95:947


Solutions I've tried:

1.  Separating the pass rule into two directional rules (as seen above)
instead of using just one rule with bidirectional operator

2.  Configured the event_queue to order by priority, then made a custom
classtype "pass-rule" with the highest priority of "1", incrementing all
others +1 (hoping this would ensure my pass rules are processed first)

2.  Ran it through Dumbpig just to be sure... It reports two problems,
however they're unrelated to this:  "TCP/UDP rule with no deep packet
checks?" and "TCP, without flow."


Any idea what I may be doing wrong or why I'm still getting alerts?

Thanks in advance,
-W

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Master Visual Studio, SharePoint, SQL, ASP.NET, C# 2012, HTML5, CSS,
MVC, Windows 8 Apps, JavaScript and much more. Keep your skills current
with LearnDevNow - 3,200 step-by-step video tutorials by Microsoft
MVPs and experts. ON SALE this month only -- learn more at:
http://p.sf.net/sfu/learnnow-d2d
_______________________________________________
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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:
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