[Snort-users] SOLVED: Trouble not getting unified2 files to write.

Tony Reusser treusser at ...15879...
Tue Oct 16 11:03:10 EDT 2012

I run mine on CentOS 6.3 and I installed from the source tarball.  I don't
have any such thing under /etc/sysconfig/snort.  It looks like the rpm
installer and/or redhat imposed some additional stuff that is causing you
grief.  My advice, uninstall the rpm stuff and just get the latest source
tarball from snort.org and do the standard {tar/unzip/configure/make/make

I invoke my snort instances with nothing but a -dD flag.  (-d) to dump the
application layer and (-D) to run in daemon mode.  Then I just have that
command in my /etc/rc.local for automatic startup at boot.  I don't worry
about any fancy/schmancy startup scripts or services.  I need two instances
of snort for my two interfaces anyway.  Each one has its own distinct .conf
file too.  Each one has a single output line that creates a single unified2
file with [interface].u2.[timestamp] for a file name that barnyard reads for
the database.  In my BASE GUI, I have all alerts and packet captures at the
click of a button.  It works really well.  On my busiest interface I get
maybe a .01% packet loss.  That is acceptable to me.

Try the manual install/setup and I bet all your headaches will go away.

Just my 2 cents.


-----Original Message-----
From: Thomison, Lee [mailto:ThomisonL at ...15885...] 
Sent: Monday, October 15, 2012 6:10 PM
To: 'snort-users at lists.sourceforge.net'
Subject: [Snort-users] SOLVED: Trouble not getting unified2 files to write.

Apparently, the -b (log packets in tcpdump style format) (in Redhat
sysconfig/snort it's BINARY_LOG) blocks unified2 output statements that
appear in /etc/snort/snort.conf

So, I had two problems:

1.  redhat was asserting the -b flag in the command line output from
/etc/init.d/snortd, and

2.  redhat was actually including the -A flag in the command line output.

Here is my existing /etc/sysconfig/snort, modified from the one included
with the src.rpm file.

# /etc/sysconfig/snort

# $Id$

# All of these options with the exception of -c, which tells Snort where

# the configuration file is, may be specified in that configuration file as

# well as the command line. Both the command line and config file options

# are listed here for reference.

#### General Configuration

# What interface should snort listen on?  [Pick only 1 of the next 3!]

# This is -i {interface} on the command line

# This is the snort.conf config interface: {interface} directive



# The following two options are not directly supported on the command line

# or in the conf file and assume the same Snort configuration for all

# instances


# To listen on all interfaces use this:



# To listen only on given interfaces use this:

#INTERFACE="eth1 eth2 eth3 eth4 eth5"

# Where is Snort's configuration file?

# -c {/path/to/snort.conf}


# What user and group should Snort drop to after starting? This user and

# group should have very few privileges.

# -u {user} -g {group}

# config set_uid: user

# config set_gid: group



# Should Snort change the order in which the rules are applied to packets.

# Instead of being applied in the standard Alert->Pass->Log order, this will

# apply them in Pass->Alert->Log order.

# -o

# config order: {actions in order}

# e.g. config order: log alert pass activation dynamic suspicious redalert


#### Logging & Alerting

# NOTE: NO_PACKET_LOG and BINARY_LOG, ALERTMODE, etc. are mutually

# exclusive. Use either NO_PACKET_LOG or any/all of the other logging

# options. But the more logging options use you, the slower Snort will run.

# Where should Snort log?

# -l {/path/to/logdir}

# config logdir: {/path/to/logdir}


# How should Snort alert? Valid alert modes include fast, full, none, and

# unsock.  Fast writes alerts to the default "alert" file in a single-line,

# syslog style alert message.  Full writes the alert to the "alert" file

# with the full decoded header as well as the alert message.  None turns off

# alerting. Unsock is an experimental mode that sends the alert information

# out over a UNIX socket to another process that attaches to that socket.

# -A {alert-mode}

# output alert_{type}: {options}


# Should Snort dump the application layer data when displaying packets in

# verbose or packet logging mode.

# -d

# config dump_payload


# Should Snort keep binary (AKA pcap, AKA tcpdump) logs also? This is

# recommended as it provides very useful information for investigations.

# -b

# output log_tcpdump: {log name}


# Should Snort turn off packet logging?  The program still generates

# alerts normally.

# -N

# config nolog


# Print out the receiving interface name in alerts.

# -I

# config alert_with_interface_name


# When dumping the stats, what log file should we look in


# When dumping the stats, how long to wait to make sure that syslog can

# flush data to disk


# To add a BPF filter to the command line uncomment the following variable

# syntax corresponds to tcpdump(8)

#BPF="not host"

# To use an external BPF filter file uncomment the following variable

# syntax corresponds to tcpdump(8)

# -F {/path/to/bpf_file}

# config bpf_file: /path/to/bpf_file


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