Snort mailing list archives

Re: snort inline behavior


From: "Josh Berry" <josh.berry () netschematics com>
Date: Wed, 26 Nov 2003 08:40:17 -0600 (CST)

Yes, when you shutdown Snort-Inline on the interfaces that connections are
coming in and out of then IPTables sends packets to the QUEUE but there is
nothing to inspect them and pass them on.  I suggest having another NIC
for managment of the box and not running snort-inline on that NIC.

First, thanks to all for the help on getting the right inline version
running.

I went through my firewall script and every '-j ACCEPT' I had, I changed
to
'-j QUEUE' and re-built my iptable chains.  Did `insmod ip_queue`, loaded
fine.  Started up snort_inline with '-DQ -l ... -c ...'.  Everything
looked
fine.  After a couple of minutes I decided instead of -D (daemon) I'd
rather
see a little output to make sure it was seeing packets as expected.  I was
ssh'ed into the box so I figured my iptables "ESTABLISHED,RELATED -j
QUEUE"
entry should show a lot of ssh packets.  I do a `kill` on the snort_inline
pid and suddenly my ssh connection goes dead - I'm waiting for it to
timeout
now.  In the mean time I've tried to re-ssh back into the box, but they
just
time out.

I'm wondering if this is some weird deal that if you don't have someone
running on QUEUE that the packets never get ACCEPTed and by shutting snort
down I just shot myself in the foot.

I'm going to go ahead and set up another box (that one is 1hr away, and
the
tech guy will arive in the morning and I'll walk him through changing
QUEUE
back to ACCEPT and restart the firewall...) and getting it tested locally
where if it breaks I can fix it easily.

In the mean time I was wondering if you guys could lend your experience
here.  Does killing snort_inline while it's watching the QUEUE break any
connections that are getting -j QUEUEed?  What happened here?

Thanks!



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Thanks,
Josh Berry, CTO
LinkNet-Solutions
469-831-8543
josh.berry () linknet-solutions com



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