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

Russ Combs rcombs at ...1935...
Fri Aug 6 15:51:02 EDT 2010


On Fri, Aug 6, 2010 at 3:36 PM, Will Metcalf <william.metcalf at ...11827...>wrote:

> 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.
>

The -i is parsed but not used to control the mode in this case.  So it is
running inline.

>
> 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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