[Snort-users] snort inline mode is not working with iptables

Will Metcalf william.metcalf at ...11827...
Fri Aug 6 15:36:15 EDT 2010


Yes I understand... Not sure if it matters but did you remove the "-i
eth1" from the command line?  Not sure how this is handled now in
snort, if this is valid for use with -Q or if it is just using one
runmode over the other.

Regards,

Will

On Fri, Aug 6, 2010 at 2:27 PM, netchild ccie <netchildccie at ...125...> wrote:
> Hi William,
> I've the traffic on that interface IN/OUT and even with both chain IN/OUT
> jump to QUEUE didn't work.
> The behavior I'm getting is that all the traffic for the rule -j QUEUE is
> being dropped as if the packets are not being handled by snort (default
> behavior for -j QUEUE if no application is handling the traffic).
> Regards,
> Wael
>> Date: Fri, 6 Aug 2010 14:03:30 -0500
>> Subject: Re: [Snort-users] snort inline mode is not working with iptables
>> From: william.metcalf at ...11827...
>> To: netchildccie at ...125...
>> CC: snort-users at lists.sourceforge.net; hat_gh at ...131...
>>
>> lose the -i eth1... Also for traffic in/out of the local ip stack for
>> tcp traffic you need to make sure that snort sees both sides of the
>> conversation. i.e.
>>
>> iptables -I INPUT -p tcp --sport 80 -j QUEUE
>> iptables -I OUTPUT -p tcp --dport 80 -j QUEUE
>>
>> Regards,
>>
>> Will
>> On Fri, Aug 6, 2010 at 1:41 PM, netchild ccie <netchildccie at ...125...>
>> wrote:
>> > Dear list,
>> > I a new user to Snort and this is my first experience with.
>> > My issue is that; it seems the snort does not communicate correctly with
>> > iptables. I have a linux machine run SNORT 2.8.6 and connected to LAN
>> > with
>> > another linux machine. I am using the other machine to ping the snort
>> > server. every time I am running snort without iptables, the ping is
>> > working
>> > and once I am using the iptables then launch snort, the ping stopped and
>> > I received alert messages!!!! I can not understand why snort drop the
>> > packets?!
>> >
>> > I'll try to summarized my issue in points
>> > 1. I've built linux machine with CentOS 4.8
>> > 2. I've downloaded snort 2.8.6 from snort website
>> > 3. I've compiled the package after I installed successfully libipq and
>> > libnet 1.0.2a. I used the following commands
>> > ./configure --enable-inline
>> > make
>> > make install
>> > 4. I've built a simple rule under /etc/snort/rules as the below and
>> > named
>> > "local.rule"
>> > alert icmp any any <> any any (msg: "ICMP DROPPED"; sid: 1000001;)
>> > 5. I loaded ip_queue model and verify it as below
>> > [root at ...14955... rules]# modprobe ip_queue
>> > [root at ...14955... rules]# lsmod | grep queue
>> > ip_queue               44777  0
>> > 5. I launched iptables before I started snort as below and verify
>> > iptables -A OUTPUT -p icmp -j QUEUE
>> > [root at ...14955... rules]# iptables -L
>> > Chain INPUT (policy ACCEPT)
>> > target     prot opt source               destination
>> > Chain FORWARD (policy ACCEPT)
>> > target     prot opt source               destination
>> > Chain OUTPUT (policy ACCEPT)
>> > target     prot opt source               destination
>> > QUEUE      icmp --  anywhere             anywhere
>> > 6. I've run snort as below
>> > [root at ...14955... rules]# snort -k none -c /etc/snort/snort.conf.wael -l
>> > /var/log/snort/wael -Q -i eth1
>> > Enabling inline operation
>> > Running in IDS mode
>> >         --== Initializing Snort ==--
>> > Initializing Output Plugins!
>> > Initializing Preprocessors!
>> > Initializing Plug-ins!
>> > Parsing Rules file "/etc/snort/snort.conf.wael"
>> > PortVar 'HTTP_PORTS' defined :  [ 80 2301 3128 7777 7779 8000 8008 8028
>> > 8080
>> > 8180 8888 9999 ]
>> > PortVar 'SHELLCODE_PORTS' defined :  [ 0:79 81:65535 ]
>> > PortVar 'ORACLE_PORTS' defined :  [ 1521 ]
>> > .
>> > .
>> > .
>> >         --== Initialization Complete ==--
>> >    ,,_     -*> Snort! <*-
>> >   o"  )~   Version 2.8.6.1 (Build 39)
>> >    ''''    By Martin Roesch & The Snort Team:
>> > http://www.snort.org/snort/snort-team
>> >            Copyright (C) 1998-2010 Sourcefire, Inc., et al.
>> >            Using PCRE version: 6.6 06-Feb-2006
>> >            Rules Engine: SF_SNORT_DETECTION_ENGINE  Version 1.12  <Build
>> > 18>
>> > 7. Verify through the log
>> > Aug  6 21:38:45 xen1 snort: [1:1000001:0] ICMP DROPPED {ICMP}
>> > 10.6.211.155
>> > -> 10.6.211.53
>> > Aug  6 21:39:16 xen1 last message repeated 31 times
>> > Aug  6 21:40:17 xen1 last message repeated 61 times
>> >
>> > 8. verify the ping from the ping's screen
>> > [root at ...14956... ~]# ping 10.6.211.53
>> > PING 10.6.211.53 (10.6.211.53) 56(84) bytes of data.
>> > <nothing>
>> >
>> > what I have missed?!
>> > Regards,
>> > Wael,
>> >
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