[Snort-users] no http traffic detected at all

Edwin Smulders edwin.smulders at ...16852...
Fri May 16 07:09:29 EDT 2014


I had already disabled lro, gro because those were mentioned by other guides (although i read here that those are not preserved at boot). I have disabled all the settings as per the article:

> for i in rx tx sg tso ufo gso gro lro; do ethtool -K eth0 $i off; done

I’ve made a new pcap (attached) and tried again. Slightly different results this time, but not quite what i want yet.

Relevant output from running snort: http://paste.debian.net/99926/

I now detect HTTP response headers, so progress!



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On 16 May 2014, at 12:42, Doug Burks <doug.burks at ...11827...> wrote:

> Hi Edwin,
> 
> Have you disabled NIC offloading features?
> http://blog.securityonion.net/2011/10/when-is-full-packet-capture-not-full.html
> 
> On Fri, May 16, 2014 at 6:04 AM, Edwin Smulders
> <edwin.smulders at ...16852...> wrote:
>> Hello,
>> 
>> I have a problem I would like some help with, the http inspect preprocessor is not correctly identifying http methods. In my test setup I have 2 machines, 1x Debian 7 (192.168.10.105) and 1x CentOS 6.5 (192.168.10.107). Both are vmware guests.
>> On both these machines I have made a tcpdump of some HTTP requests - just simple wgets.
>> 
>> On both machines I also have a snort install - 2.9.6.1 from the rpm package and self compiled on the debian machine.
>> At first I was thinking the debian install was having problems detecting HTTP traffic, but it’s slightly different.
>> 
>> When I load the CentOS tcpdump in both installs, they both detect HTTP GET Requests.
>> When I load the debian tcpdump in both installs, neither detects HTTP GET Requests.
>> 
>> I’ve attached the tcpdumps (if that works to the mailing list, otherwise I’ll host them somewhere), can anybody help me find out what is different?
>> 
>> Note that the same thing happened in the (a bit older) snort version + config in the debian package manager.
>> 
>> Config for the debian machine: http://paste.debian.net/99908/
>> Config for the centos machine: http://paste.debian.net/99909/
>> They should be similar except for paths. Most rules should be disabled, this is just about the http inspect preprocessor detecting the correct methods.
>> 
>> I have output logs for the following commands:
>> 
>> root at ...16853...:/home/esmulders/snort-2.9.6.1# /usr/local/bin/snort -c etc/snort.conf -H -U -A cmg -r http-debian.pcap &> snort-debianpcap.log
>> root at ...16853...:/home/esmulders/snort-2.9.6.1# /usr/local/bin/snort -c etc/snort.conf -H -U -A cmg -r http-centos.pcap &> snort-centospcap.log
>> 
>> snort-debianpcap.log: http://paste.debian.net/99910/
>> snort-centospcap.log: http://paste.debian.net/99911/
>> 
>> In these outputs the relevant lines are:
>> GET methods:                          0
>> and
>> GET methods:                          10
>> 
>> Can somebody help me debug this? Let me know if you have debugging tips or if I can provide some more information.
>> I’m available on Freenode/#snort as Dutchy for direct communication (european timezone/business hours work best for me).
>> 
>> 
>> Regards,
>> Edwin
>> 
>> 
>> 
>> 
>> 
>> 
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> 
> 
> 
> -- 
> Doug Burks

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