Snort mailing list archives
Ongoing reputation issues
From: Dave Corsello <snort-users () wintertreemedia com>
Date: Wed, 21 May 2014 11:23:05 -0400
I was recently able to clear up problems with the reputation
preprocessor on my home system by adding a couple of parameters to my
snort start-up command. I applied that change at a client location, but
the reputation problems continue at the client. The problem is that in
an outbound HTTP request to a reputation-blocked IP address, the request
fails, but pcaps show that the TCP handshake succeeds. Also, snort
alerts that the SYN and SYN ACK packets are blocked, even though they
are not. So snort is making a decision that is not followed by the NFQ
DAQ and/or iptables for some reason.
Following are the contents of the main configuration files; they are
identical to the config files on my home office system except for the IP
addresses. My distro is Ubuntu server 10.04.3 LTS, my snort version is
2.9.6.1 and my daq version is 2.0.2. Snort was configured with
--enable-sourcefire and --enable-reload. DAQ was configured with
defaults. Can anyone spot a problem that would allow the TCP handshake
to succeed with a reputation-blocked IP address?
#########################
/etc/network/interfaces
#########################
# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).
# The loopback network interface
auto lo
iface lo inet loopback
# The primary network interface
# The management network interface
auto eth2
iface eth2 inet static
address a.a.a.a
netmask 255.255.255.0
network a.a.a.0
broadcast a.a.a..255
gateway a.a.a.1
# dns-* options are implemented by the resolvconf package, if
installed
dns-nameservers a.a.a.b
dns-search mydomain.com
# The bridge for Snort IPS
auto br0
iface br0 inet manual
bridge-ports eth0 eth1
pre-up iptables-restore < /etc/iptables.rules
# pre-up iptables-restore < /etc/iptables-noqueue.rules
#########################
/etc/resolv.conf
#########################
nameserver a.a.a.b
nameserver a.a.a.c
domain mydomain.com
search mydomain.com
#########################
/etc/iptables.rules
#########################
# Generated by iptables-save v1.4.4 on Wed Apr 6 00:59:09 2011
*filter
:INPUT ACCEPT [0:0]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
-A FORWARD -j NFQUEUE --queue-num 1
COMMIT
# Completed on Wed Apr 6 00:59:09 2011
#########################
/etc/init/snort.conf
#########################
# Snort Service
description "Snort IPS"
author "Dave Corsello"
start on (net-device-up
and local-filesystems
and runlevel [2345])
stop on runlevel [016]
respawn
exec /usr/local/bin/snort -Q --daq nfq --daq-var device=br0 --daq-var
queue=1 -c /etc/snort/snort.conf -D
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Current thread:
- Ongoing reputation issues Dave Corsello (May 21)
- Re: Ongoing reputation issues James Lay (May 21)
- Re: Ongoing reputation issues Dave Corsello (May 21)
- Re: Ongoing reputation issues James Lay (May 21)
- Message not available
- Message not available
- Message not available
- Re: Ongoing reputation issues Dave Corsello (May 22)
- Re: Ongoing reputation issues Dave Corsello (May 21)
- Re: Ongoing reputation issues James Lay (May 21)
