Re: Snort 2.9.6.2 inline mode problem

[Y M <snort () outlook com>]

> As already posted I run it with: >/usr/sbin/snort -D -i eth1:eth2 -u snort -g snort -c /etc/snort/snort.conf -l 
> /var/log/snort -Q --daq-mode inline -k none


You can drop "--daq-mode inline" from your command since you already have the mode defined in snort.conf. Does the box 
running Snort do anything else other than just running Snort?

Run tcpdump to capture the traffic while running Snort and test again. See what information the capture might provide. 
It's a crapshoot but you may also want to test on another distro, we have one specific case where things didn't work as 
expected on one distro while it worked fine on another.
YM

On Mon, Aug 25, 2014 at 7:18 PM, Y M <snort () outlook com> wrote:




Please post your snort.conf, sanitizing any private info. Also the command you use to run Snort.
YM

Date: Sun, 24 Aug 2014 19:58:22 +0200
Subject: Re: [Snort-users] Snort 2.9.6.2 inline mode problem

From: demonsdebason () gmail com
To: snort () outlook com
CC: snort-users () lists sourceforge net


I have already tried with this rule:
drop icmp 192.168.1.2 any -> 8.8.8.8 any (msg: "NEW TEST"; sid:10666;)

Also modified 384 ICMP rule:
drop icmp $EXTERNAL_NET any -> $HOME_NET any (msg:"PROTOCOL-ICMP PING"; icode:0; itype:8; metadata:ruleset community; 
classtype:misc-activity; sid:384; rev:8;)



Set HOME_NET to any, restarted Snort and got the same crap:
PING 8.8.8.8 (8.8.8.8) 56(84) bytes of data.
> From 8.8.8.8 icmp_seq=1 Destination Port Unreachable
64 bytes from 8.8.8.8: icmp_seq=1 ttl=46 time=40.6 ms


> From 8.8.8.8 icmp_seq=2 Destination Port Unreachable
> From 8.8.8.8 icmp_seq=3 Destination Port Unreachable
64 bytes from 8.8.8.8: icmp_seq=3 ttl=46 time=40.7 ms


I've set additional rule:

drop icmp any any -> any any (msg: "NEW TEST"; sid:10666;)

...and am getting:
PING 8.8.8.8 (8.8.8.8) 56(84) bytes of data.
> From 8.8.8.8 icmp_seq=1 Destination Port Unreachable
64 bytes from 8.8.8.8: icmp_seq=1 ttl=46 time=40.2 ms


> From 8.8.8.8 icmp_seq=2 Destination Port Unreachable
> From 8.8.8.8 icmp_seq=3 Destination Port Unreachable
> From 8.8.8.8 icmp_seq=4 Destination Port Unreachable
> From 8.8.8.8 icmp_seq=5 Destination Port Unreachable


64 bytes from 8.8.8.8: icmp_seq=5 ttl=46 time=40.6 ms
> From 8.8.8.8 icmp_seq=6 Destination Port Unreachable

Tried with and without normalization, works the same.



Snort is blocking, but seems not to be able to drop all the traffic:
08/24-19:56:03.511103  [Drop] [**] [1:10666:0] NEW TEST [**] [Priority: 0] {ICMP} 192.168.1.2 -> 8.8.8.8
08/24-19:56:03.511145  [Drop] [**] [1:10666:0] NEW TEST [**] [Priority: 0] {ICMP} x.x.x.x -> 8.8.8.8


08/24-19:56:03.551092  [Drop] [**] [1:10666:0] NEW TEST [**] [Priority: 0] {ICMP} 8.8.8.8 -> 192.168.1.2
08/24-19:56:03.551058  [Drop] [**] [1:10666:0] NEW TEST [**] [Priority: 0] {ICMP} 8.8.8.8 -> x.x.x.x





On Sun, Aug 24, 2014 at 6:29 PM, Y M <snort () outlook com> wrote:





Ok, assuming you are setup this way:
Internet <---> eth2 | IPS | eth1 <---> local, where eth1 and eth2 are the listening (promiscuous) interfaces and 
through which traffic is passing. When you force Snort into inline mode using afpacket, Snort (logically) bridges the 
interfaces together to let the traffic pass, otherwise drop it when matches occur. Looking again at the rule you have, 
both destinations are local. What happens if you change both destinations (HOME_NET and EXTERNAL_NET) to any/any? 
Better, take rule sid:384 and modify it and try to ping an external source and see what happens. For troubleshooting 
purposes only, run Snort with -A console or -A cmg so you can see whats going directly on the console (without -D).


Also, do you have normalization enabled?
YM
Date: Sun, 24 Aug 2014 17:50:27 +0200
Subject: Re: [Snort-users] Snort 2.9.6.2 inline mode problem
From: demonsdebason () gmail com


To: snort () outlook com
CC: snort-users () lists sourceforge net


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 () outlook com> 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 () gmail com
To: snort () outlook com

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 () outlook com> wrote:





inline.
Date: Sun, 24 Aug 2014 05:02:13 +0200
From: demonsdebason () gmail com
To: snort-users () 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
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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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