{{tag>[security snort centos6.5]}}
=====Snort 2.9.6.1 on CentOS 6.5=====
====Install prerequisites====
  * EPEL repo
  * RPMForge repo
  * Download snort and daq RPM's from snort.org
  * Install RPM's<code>yum install libdnet-1.11-1.2.el6.rf.x86_64    #rpmforge
yum localinstall ./daq-2.0.2-1.centos6.x86_64.rpm
yum localinstall ./snort-2.9.6.1-1.centos6.x86_64.rpm
</code>

====Configure Snort====
  * Edit **/etc/sysconfig/snort**
<code>
mkdir -p /usr/local/lib/snort_dynamicrules
chown -R snort:snort /usr/local/lib/snort_dynamicrules
chmod -R 700 /usr/local/lib/snort_dynamicrules
</code>
Copy any dynamic rulesets you have or are using to the above directory.

====Test rule====
Put as last line in snort.conf
  alert icmp any any -> 1.2.3.4 any (msg: "Gateway ping"; sid:10000001;)

Find the alerts in the log
<code>
05/09-09:00:07.648953  [**] [1:10000001:0] Gateway ping [**] [Priority: 0] {ICMP} 6.7.8.9 -> 1.2.3.4
05/09-09:00:07.654956  [**] [1:10000001:0] Gateway ping [**] [Priority: 0] {ICMP} 6.7.8.9 -> 1.2.3.4
05/09-09:00:07.660981  [**] [1:10000001:0] Gateway ping [**] [Priority: 0] {ICMP} 6.7.8.9 -> 1.2.3.4
05/09-09:00:07.666729  [**] [1:10000001:0] Gateway ping [**] [Priority: 0] {ICMP} 6.7.8.9 -> 1.2.3.4
</code>

You can even show contents of the packets with tcpdump
  tcpdump -r snort.log.1399615922