Snort mailing list archives

Re: Basics of setting up an inline snort installation


From: Dave Kelly <bigdavekelly () googlemail com>
Date: Fri, 10 Feb 2012 00:01:49 +0000

Thanks Lynemose and Russ, hopefully that'll be enough to get me going.

I'd tried googling snort inline and have read the manual but couldn't
quite make it work in my head.  It's clicked, talking about bridging.
I'll be playing with that now, and I'm sure I'll be back with more
questions :-)

On Thu, Feb 9, 2012 at 6:54 PM, Heine Lysemose <lysemose () gmail com> wrote:
Here's my input...

Test Snort with this command
/usr/local/snort/bin/snort --daq afpacket -Q -c
/usr/local/snort/etc/snort.conf -i eth1:eth2 --daq-dir /usr/local/lib/daq

If you like to run it as a daemon add -D to the line above.

Configure the network interfaces eth0, eth1 and eth2. Interface eth0,
management interface, will have a static IP address on our internal LAN and
eth1 and eth2 will be setup in promiscuous mode.

Edit /etc/network/interfaces

auto eth0
iface eth0 inet static
address 192.168.1.10
netmask 255.255.255.0
gateway 192.168.1.1

auto eth1
iface eth1 inet manual
up ifconfig eth1 0.0.0.0 up
up ip link set eth1 promisc on

auto eth2
iface eth2 inet manual
up ifconfig eth2 0.0.0.0 up
up ip link set eth2 promisc on

Also try looking at this site from
SecurityOnion, http://code.google.com/p/security-onion/wiki/NetworkConfiguration

/Lysemose

On Thu, Feb 9, 2012 at 7:43 PM, PS <packetstack () gmail com> wrote:

If I have three interfaces, wan (eth0), lan1(eth1), and lan2 (eth2), could
I specify an interface pair of eth0:eth1::eth0:eth2 or do both pairs need to
have unique interfaces?

On Feb 9, 2012, at 1:22 PM, Russ Combs <rcombs () sourcefire com> wrote:



On Thu, Feb 9, 2012 at 1:11 PM, PS <packetstack () gmail com> wrote:

When I first setup snort inline I only had two interfaces. One being my
wan interface (eth0) and the other the LAN interface (eth1). I am able to
run inline with just those two interfaces, but it is not recommended. Both
are set to promiscuous mode. So it can be done with two if you really need
to. Both interfaces have IP addresses.

As for them needing IP addresses, I am not sure how it could be inline
without IP addresses. How would traffic be routed?


Inline operation doesn't require IP addresses on the non-management port
and it is probably better that they don't have IP addresses.  In inline mode
you are just a "bump in the wire", and not routable apart from the
management port.


Again, it's best if you have a third interface for management.


On Feb 9, 2012, at 12:29 PM, Dave Kelly <bigdavekelly () googlemail com>
wrote:

Thanks, that might make a bit more sense!  So the two interfaces that
are bridging don't need IP addresses?  I haven't seen a guide to
setting this up anywhere, do you know of one?

Dave.

On Thu, Feb 9, 2012 at 4:21 PM, Heine Lysemose <lysemose () gmail com>
wrote:
Hi,

To setup Snort as inline you need 3 network interface and pass your
traffic
through a bridge between 2 of the interfaces and a 3. for
administration.
You can start Snort with -Q to enable inline.

/Lysemose

On Feb 9, 2012 4:23 PM, "Dave Kelly" <bigdavekelly () googlemail com>
wrote:

Hello,

I'm going to try setting up a new inline configuration, I've only
tried passive before but would like Snort to be able to drop packets
it says are bad.  I'm trying to work out the IP addressing for it. At
the moment, I have all my machines in 192.168.1.0/24 with a router at
192.168.1.1 and a mirrored port on the switch sending all traffic to
snort.

It's pretty similar to the Ubuntu getting started guide in the docs
("Snort 2.9.2.0 on Ubuntu 10.04 LTS").

I think that to move snort to inline I'm going to need to give it a
proper IP address and have the traffic pass through it but I can't
quite work out how to do that without reconfiguring all the hosts to
have new gateway addresses etc.  Any hints to get me going would be
much appreciated.

Dave.



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