OSSEC
Copyright (C) 2009 Trend Micro Inc.


** Nmap correlation **

Ossec can read nmap grepable output files to use as a
correlation tool and also to alert based on host information
changes. Follow the step by step below on how to configure
ossec:


1- Add the nmap output file on ossec.conf (generally 
   at /var/ossec/etc/ossec.conf):

<ossec_config>
  <localfile>
    <log_format>nmapg</log_format>
    <location>/var/log/nmap-out.log</location>
  </localfile>
</ossec_config>


2- If the file does not exist, touch it:

ossec-test# touch /var/log/nmap-out.log


3- Restart ossec:

ossec-test# /var/ossec/bin/ossec-control restart


4- Run your nmap scans (example scanning 192.168.2.0/24 network):

ossec-test# nmap --append_output -sU -sT -oG /var/log/nmap-out.log 192.168.2.0-255



*** Example of alert when a new host is found:

** Alert 1152058913.238: mail
2006 Jul 04 20:21:53 /var/log/nmap-out.log
Rule: 15 (level 8) -> 'New host information added.'
Src IP: (none)
User: (none)
Host: 192.168.2.10, open ports: 21(tcp) 22(tcp) 80(tcp) 113(tcp) 514(udp) 1514(udp) 4500(udp)


*** Example of alert when a new a host information is changed:

** Alert 1152058983.487: mail
2006 Jul 04 20:23:03 /var/log/nmap-out.log
Rule: 15 (level 8) -> 'Host information changed.'
Src IP: (none)
User: (none)
Host: 192.168.2.1, open ports: 54(udp) 8080(tcp) 161(udp) 520(udp) 1025(udp) 1900(udp)
Previously open ports: 53(udp) 80(tcp) 161(udp) 520(udp) 1025(udp) 1900(udp)

