[Snort-users] Snort 2.9.6.2 inline mode problem

Debason Shockre demonsdebason at ...11827...
Sun Aug 24 11:50:27 EDT 2014


Here is the setup:

INTERNET <--> | IPS/router | <--> | local machines |

IPS box has 4 interfaces, where 2 have an address, others don't. It seemed
illogical to set Snort to listen on interfaces where no traffic is passing
through.
When I set Snort it to use unaddressed interfaces, nothing happens meaning
no alerts are recorded and ICMP echo test isn't working.
Tried setting up bride interfaces and assigning the two unaddressed
interface to Snort, same results.
The only results I get is having Snort listening the interfaces traffic
traverse though.


On Sun, Aug 24, 2014 at 4:24 PM, Y M <snort at ...15979...> wrote:

> How are you testing/connecting the client (icmp echo request sender), the
> sensor, and the receiver of the icmp? The NICs that Snort is using to
> receive --> pass/drop --> forward traffic should be inline with no IP
> addresses. From your description, it seems that you are using the same
> interface to ping the box as well as do the IPS work.
>
> P.S.: Please respond to the list and not only to myself. Its a mutual
> benefit.
>
> YM
>
> ------------------------------
> Date: Sun, 24 Aug 2014 14:00:20 +0200
> Subject: Re: [Snort-users] Snort 2.9.6.2 inline mode problem
> From: demonsdebason at ...11827...
> To: snort at ...15979...
>
>
> The same behavior when running with 'eth1:eth2'.
> Yeah, the interfaces are in promiscuous, silly me.
> Any ideas?
>
>
> On Sun, Aug 24, 2014 at 7:34 AM, Y M <snort at ...15979...> wrote:
>
>
> inline.
> ------------------------------
> Date: Sun, 24 Aug 2014 05:02:13 +0200
> From: demonsdebason at ...11827...
> To: snort-users at lists.sourceforge.net
> Subject: [Snort-users] Snort 2.9.6.2 inline mode problem
>
>
> Hi all.
> I've been working on my Snort IPS for some time now.
> Noticed that 'drop' rules are working half-way, I have set the test rule
> to drop ICMP coming to the sensor from local machine:
> drop icmp 192.168.1.2 any -> 192.168.1.1 any (msg: "Test rule";
> sid:110011;)
>
> Alerts get logged and can view them via BASE, but when I ping from .2 to
> .1 I get this:
> PING 192.168.1.1 (192.168.1.1) 56(84) bytes of data.
> 64 bytes from 192.168.1.1
>
> : icmp_seq=1 ttl=64 time=0.216 ms
> From 192.168.1.1 icmp_seq=1 Destination Port Unreachable
> 64 bytes from 192.168.1.1
>
> : icmp_seq=2 ttl=64 time=0.269 ms
> >From 192.168.1.1 icmp_seq=2 Destination Port Unreachable
> 64 bytes from 192.168.1.1
>
> : icmp_seq=3 ttl=64 time=0.221 ms
>
> So some of them are getting 'blocked'.
>
> When I shutdown Snort I's all fine:
> 64 bytes from 192.168.1.1
>
> : icmp_seq=8 ttl=64 time=0.226 ms
> 64 bytes from 192.168.1.1
>
> : icmp_seq=9 ttl=64 time=0.201 ms
> 64 bytes from 192.168.1.1
>
> : icmp_seq=10 ttl=64 time=0.253 ms
> 64 bytes from 192.168.1.1
>
> : icmp_seq=11 ttl=64 time=0.204 ms
>
> Here is my info:
>
>    ,,_     -*> Snort! <*-
>   o"  )~   Version 2.9.6.2 GRE (Build 77)
>    ''''    By Martin Roesch & The Snort Team:
> http://www.snort.org/snort/snort-team
>            Copyright (C) 2014 Cisco and/or its affiliates. All rights
> reserved.
>            Copyright (C) 1998-2013 Sourcefire, Inc., et al.
>            Using libpcap version 1.4.0
>            Using PCRE version: 7.8 2008-09-05
>            Using ZLIB version: 1.2.3
> +++++++++++++++++++++++++++
> snort    41104  4.6  2.0 1675528 1342832 ?     Ssl  04:48   0:00
> /usr/sbin/snort -D -i eth1::eth2 -u snort -g snort -c /etc/snort/snort.conf
> -Q --daq-mode inline -k none
> +++++++++++++++++++++++++++
>
> # Looks like you have double colons "eth1::eth2", as opposed to one colon
> "eth1:eth2". Not sure if the double colons are causing the partial drops.
>
>
> snort --daq-list
> Available DAQ modules:
> pcap(v3): readback live multi unpriv
> ipfw(v3): live inline multi unpriv
> dump(v2): readback live inline multi unpriv
> afpacket(v5): live inline multi unpriv
>
> ++++++++++++++++++++++++++
> snort.conf:
>
> config policy_mode:inline
> config daq: afpacket
> config daq_dir: /usr/lib64/daq
> config daq_mode: inline
> config daq_var: buffer_size_mb=1024
>
>
> I've tried dropping all the ICMPs in the iptables, results are as
> expected, but Snort still logs the alerts.
> Do you have any idea what is the issue here?
>
> # Does Snort log the requests or replies or both? I would image if the NIC
> is promiscuous, then it would still see the requests.
>
>
> --
> Aut viam inveniam aut faciam
> :wq!
>
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>
> --
> Aut viam inveniam aut faciam
> :wq!
>



-- 
Aut viam inveniam aut faciam
:wq!
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