Router / Protocol Problem
sam_mailinglists at spacething.org
Thu Sep 7 15:01:45 UTC 2006
John Kristoff wrote:
> On Thu, 7 Sep 2006 07:27:16 -0400
> "Mike Walter" <mwalter at 3z.net> wrote:
>> Sep 7 06:50:20.697 EST: %SEC-6-IPACCESSLOGP: list 166 denied tcp
>> 188.8.131.52(25) -> 184.108.40.206(2421), 4 packets
> I'm not very familiar with NBAR or how to use it for CodeRed, but this
> first rule:
>> access-list 166 deny ip any any dscp 1 log
> Seems dubious. So I'm not not sure what sets the codepoint to 000001
> by default, but apparently CodeRed does? Nevertheless, this seems like
> a very weak basis for determining whether something is malicious.
It's his NBAR config lower down that sets the dscp value:
class-map match-any http-hacks
match protocol http url "*default.ida*"
match protocol http url "*cmd.exe*"
match protocol http url "*root.exe*"
set ip dscp 1
So, there's probably two things that could happen here: One, NBAR is
incorrectly identifying the SMTP traffic as code red, or two, the SMTP
traffic is already marked with dscp 1. If you've using these values
internally in your own network then they should be reset on all
externally received traffic.
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