[Snort-users] Snort tcp reset

Daniele Gallarato daniele.gallarato at ...11827...
Tue May 8 08:44:11 EDT 2012


I've other information.

My snort is passive, it sniff from eth1 (a monitor interface on a cisco
switch), and is monitored with eth0 interface.
So, we need that tcp reset come to eth0 interface, but if I sniff traffic
with tcpdump, I can see that tcp reset is send through eth1, and eth1 can't
send traffic (due to monitor interface limitation).
With flexresp2 we can choose which interface use for reset

flexresp2 interface: eth0

but this configuration option is disappeared with flexresp3.

Anyone know how to address this problem?

Thank
Daniele


2012/5/8 Daniele Gallarato <daniele.gallarato at ...11827...>

> Sorry.
>
> Anyone can address me to a documentation about tcp reset with flexresp3?
>
> Thanks
> Daniele
>
>
> 2012/5/4 Daniele Gallarato <daniele.gallarato at ...11827...>
>
>> Yes.
>>
>> I don't understand well the difference between flexresp3 (previously I've
>> used flexresp1, so I've tried to use flexresp3), and active-response.
>>
>> If I configure
>>
>> config response: device eth0 attempts 2
>>
>>
>> when snort hit a reset rule, it flood the network and I can't reach it
>> anymore...
>>
>> Thanks
>>
>>
>> * Flexresp3 is new: the resp rule option keyword is used to configure
>> active
>>   responses for rules that fire.
>>
>>     ./configure --enable-flexresp3
>>
>>     alert tcp any any -> any 80 (content:"a"; resp:<resp_t>; sid:1;)
>>
>> * resp_t includes all flexresp and flexresp2 options:
>>
>>     <resp_t> ::= \
>>         rst_snd | rst_rcv | rst_all | \
>>         reset_source | reset_dest | reset_both | icmp_net | \
>>         icmp_host | icmp_port | icmp_all
>>
>> See README.flexresp3 for more.
>>
>>
>>
>> 2012/5/4 Russ Combs <rcombs at ...1935...>
>>
>>> Did you check README.active?
>>>
>>> On Fri, May 4, 2012 at 10:00 AM, Daniele Gallarato <
>>> daniele.gallarato at ...11827...> wrote:
>>>
>>>> Hello.
>>>>
>>>> I've installed snort version 2.9.2.2 onto an ubuntu server
>>>> (2.6.32-41-server #88-Ubuntu SMP).
>>>>
>>>> I've followed this good guide:
>>>>
>>>>
>>>> http://www.google.it/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&ved=0CHsQFjAB&url=http%3A%2F%2Fwww.snort.org%2Fassets%2F158%2F014-snortinstallguide292.pdf&ei=zd-jT5vCBPTa4QSl0rifCQ&usg=AFQjCNGaL8nB1vZPRodUBX6IQluwufpbFQ&sig2=FqFj5w3hOXP1NBcn3gbxoQ
>>>>
>>>> All seems to work properly.
>>>>
>>>> Only thing that doesn't work is flexresp3.
>>>>
>>>> In an old installation (2.4.3) with old flexresp, resets work.
>>>>
>>>> In this new installation, I've compiled snort with:
>>>>
>>>> ./configure --prefix=/usr/local/snort --enable-sourcefire
>>>> --enable-active-response --enable-flexresp3
>>>> make
>>>> make install
>>>>
>>>> and written some local.rules (they work) and some reset.rules (they hit
>>>> the rule, appear in reports, but doesn't reset).
>>>>
>>>> Rule is:
>>>>
>>>> alert tcp <my_ip> any -> $HOME_NET 3389 (resp: rst_all; msg:"Reset
>>>> Sessioni Remote Desktop" ; sid:200004;)
>>>>
>>>> I've also checked packets with wireshark, I can't see any reset.
>>>>
>>>> Any help will be appreciated.
>>>>
>>>> Thanks
>>>> Daniele Gallarato
>>>>
>>>>
>>>>
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>>
>
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