[Snort-sigs] A question on ethernet padding

Jeremy Hoel jthoel at ...2420...
Thu Jan 23 15:25:42 EST 2014


BTW -  I think snort might count the icmp code/type/protocol bits as
part of data, so making it dsize:>31; fixed it.  Thanks!

On Thu, Jan 23, 2014 at 8:20 PM, Jeremy Hoel <jthoel at ...2420...> wrote:
> So there you go.. I was trying various offsets and depths and didn't
> seem to get it.  But I'll try that.  Thanks!
>
>
> BTW - Should that be part of the rule?  Since you wouldn't want those
> to fire if they had 0 data?
>
>
>
> On Thu, Jan 23, 2014 at 8:17 PM, James Lay <jlay at ...3266...> wrote:
>> On 2014-01-23 12:54, Jeremy Hoel wrote:
>>>
>>> I was wondering kind of the same question.. in regards to those new
>>> ICMP rules.  NetApps doing have any ICMP data, just the main requests,
>>> but there seems to always be 10 bytes |00| in what wireshark calls
>>> padding, and I'm curious if I can write the rule around that.
>>>
>>> On Thu, Jan 23, 2014 at 4:07 PM, James Lay <jlay at ...3266...>
>>> wrote:
>>>>
>>>> Does snort treat ethernet padding as data?  Wireshark shows that I have
>>>> 1 byte of data in a packet after my ethernet and ip headers.  My
>>>> ethernet header, normally 14 bytes, includes 17 bytes of Padding.  Does
>>>> snort consider the padding as data?  Trying to figure out what offset
>>>> and depth to use on this rule.  Hope I'm explaining this well..thanks
>>>> all.
>>>>
>>>> James
>>
>>
>> An end around around to NOT see these can be to add dsize:>1; to your
>> rule...should nuke out these zero data pings.
>>
>> James
>>




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