Installing Snort on CentOS 5.7

CentOS 5.7 uses an older version of libpcap (0.9.4), but Snort’s Data Acquisition Library (daq) needs a newer version of libpcap (>=1.0.0). The latter is not an issue with the CentOS 6.0. Vishesh Kumar [1] provides an excellent instructions to getting Snort 2.9 to run on RHEL 5 ( The purpose of this post is not to duplicate his efforts, but to extend it slightly to include instructions for a complete Snort set-up.

  1. libpcap - [3]
  2. daq : [2]
  3. snort : [2]

Download and install the libraries and software as per the instructions below;

Enable the Extra Packaged for Enterprise Linux (EPEL) repository to enable the installation of additional packages not available under the standard repositories

  1. rpm -Uvh
  2. yum -y update
  3. yum -y upgrade

Install developments to compile the libraries and source code, and additional libraries and header files that are required later on

  1. yum -y groupinstall ‘Development Tools'
  2. yum -y install pcre-devel
  3. yum -y install libdnet-devel
  4. yum -y install zlib-devel
  5. yum -y install mysql mysql-server mysql-devel mysql-bench

Download, compile and install libpcap

  1. wget
  2. cd libpcap-1.1.1
  3. ./configure –prefix=/usr
  4. make && make install

Download, compile and install daq

  1. wget -O daq-0.6.2.tar.gz
  2. cd daq-0.6.2
  3. ./configure
  4. make && make install

Download, compile and install snort

  1. wget -O snort-
  2. cd snort-
  3. ./configure –with-mysql
  4. make && make install

Download, compile and install Barnyard2

  1. wget –no-check-certificate -O firnsy-barnyard2-405761e.tar.gz
  2. tar zxvf firnsy-barnyard2-405761e.tar.gz
  3. cd firnsy-barnyard2-405761e
  4. ./
  5. ./configure –with-mysql
  6. make && make install

Create the snort database on the mysql enginer

mysqladmin -u root -p create snort

mysql -u root -p -D snort < schemas/create_mysql

mysql -u root -p


To get the current registered user rules, you need to sign up and obtain an Oinkcode. The Oinkcode will be used for downloading the rules and used with pulledpork.

  1. Sign in or request an account from
  2. Get your oinkcode after signing in from
  3. cd etc
  4. wget -O snortrules-snapshot-LATEST.tar.gz
  5. tar zxvf snortrules-snapshot-LATEST.tar.gz

Setup the configuration and rules files for snort

  1. mkdir -p /etc/snort
  2. mv -f etc/* .
  3. rmdir etc/
  4. mv snortrules-snapshot-LATEST.tar.gz ../../
  5. rm -f Makefile
  6. cp -rf * /etc/snort/

Edit the snort configuration

vi /etc/snort/snort.conf

  1. ipvar HOME_NET
  2. var RULE_PATH rules
  3. var SO_RULE_PATH so_rules
  4. var PREPROC_RULE_PATH preproc_rules
  5. output database: log, mysql, user=snort password=PASSWORD dbname=snort host=localhost
  6. output alert_syslog: LOG_LOCAL6 LOG_ALERT

Edit the syslog.conf file to log alerts to separate file and restart the syslog daemon

  1. Include the line in syslog.conf “local6.*        /var/log/snort/alerts.log"
  2. /etc/rc.d/init.d/syslog restart

Test the snort installation, and set-up environment to run snort if all OK

  1. snort -c /etc/snort/snort.conf -T
  2. useradd -G snort snort -s /bin/false
  3. chown -R root:snort /var/log/snort
  4. chmod -R g+w /var/log/snort

Configure barnyard [4]

mkdir -p /var/log/barnyard2

chmod 666 /var/log/barnyard2

touch /var/log/snort/barnyard2.waldo

cp etc/barnyard2.conf /etc/snort/

Edit the /etc/snort/barnyard2.conf

  1. output database: log, mysql, user=snort password= dbname=snort host=localhost
  2. config hostname:   localhost
  3. config interface:  eth0

You can get snort to start automatically, but writing a customer script to start/stop/restart the daemon or simply kicking it off to start up when the machine boots. Edit the rc.local file and out the following in

  1. /usr/local/bin/snort -D -u snort -g snort -c /etc/snort/snort.conf -i eth0
  2. /usr/local/bin/barnyard2 -c /etc/snort/barnyard2.conf -d /var/log/snort -f snort.log -w /var/log/snort/barnyard2.waldo -D

Common Errors:

ERROR: parser.c(5261) Could not stat dynamic module path “/usr/local/lib/snort_dynamicrules”: No such file or directory. Fatal Error, Quitting..

  1. mkdir -p /usr/local/lib/snort_dynamicrules
  2. cp /etc/snort/so_rules/precompiled/DIST/i386/* /usr/local/lib/snort_dynamicrules/

ERROR: /etc/snort/rules/web-misc.rules(555) Cannot use the fast_pattern content modifier for a lone http cookie/http raw uri /http raw header /http raw cookie /status code / status msg /http method buffer content. Fatal Error, Quitting..

  1. The fast_pattern option cannot be used with the http_method string. Edit the web-misc.rules file and remove it from the snort rule. Do a search for "2010-0388” and remove the alert option fast_pattern from the alert rule.

ERROR: /etc/snort/snort.conf(244) => ‘compress_depth’ and ‘decompress_depth’ should be set to max in the default policy to enable ‘unlimited_decompress’ Fatal Error, Quitting..

  1. Edit the /etc/snort/snort.conf file and set the http_inspect compress_depth and decompress_depth to 65535 from 20480.

ERROR: ByteExtract variable ‘bugtraq’ in rule [3:13897] is used before it is defined

  1. Ensure that the shared libraries copied above using “cp /etc/snort/so_rules/precompiled/DIST/i386/* /usr/local/lib/snort_dynamicrules/” are for the correct distribution
  2. Ensure that the rules being used are for the version of snort being used.

*Please note: *

  1. These instruction are for 32bit hardware, for 64bit machines you will need to select appropriate 64bit RPM packages or configure and compile with appropriate compiler switches. These are considered beyond the scope of this post.
  2. All instructions are executed with root privileges.



See also