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Snort. The Lightweight Intrusion Detection System. The other games in town. Heavyweight systems: Stateful firewalls: Example: Checkpoint Firewall One Commercial network intrusion detection systems: Example: Network Flight Recorder (NFR). The Art of Intrusion Detection:.
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Snort The Lightweight Intrusion Detection System
The other games in town Heavyweight systems: Stateful firewalls: Example: Checkpoint Firewall One Commercial network intrusion detection systems: Example: Network Flight Recorder (NFR)
The Art of Intrusion Detection: • Know the protocols. • Watch the web. • Set up your IDS monitor. • Install and tune Snort. • Set up your switches. • Watch and process logs.
Watch the web www.snort.org www.securityfocus.com csrc.nist.gov www.sans.org www.cert.org
Set up your IDS monitor Generic Intel CPU The software UNIX-like O/S with LIBPCAP
Install and tune Snort Download Tune the rules Compile
Set up your switches Remote Switch Local Switch Cross-over jumper Management VLAN User PC Snort Box The Default VLAN or ELAN
Set up your switches remote-switch# set vlan 2 port 3/2 remote-switch# set vlan 2 port 3/3 remote-switch# set span 1 3/1 create local-switch# set vlan 2 port 4/1 local-switch# set vlan 2 port 4/2
Watch and process logs • There are lots of PERL programs. • Snort can send a WINPOPUP via SMB. • Snort can log to an MSQL database. • Get fancy by going through syslog. • Tip: keep systems in sync with NTP.
Snort rule anatomy alert tcp any any - 10.1.1.0/24 80 \ (content: "/cgi-bin/phf"; msg: "PHF probe!";) alert tcp any any - 10.1.1.0/24 6000:6010 \ (msg: "X traffic";)
Snort rule anatomy IMAP attack:
Snort rule anatomy alert tcp any any - 192.168.1.0/24 143 \ (content:"|E8C0 FFFF FF|/bin/sh"; msg: \ "New IMAP Buffer Overflow detected!";)
Operational hint Run from /etc/inittab with respawn option: snort:5:respawn:/usr/local/bin/snort or a shell program: #!/bin/sh : while true do /bin/date > /var/log/snort-restart.log /usr/local/bin/snort done