Configure PSAD to ignore certain IP ranges

This post will show you how to configure Port Scan Attack Detector (or PSAD) to ignore specific IP ranges.

What is PSAD?

PSAD is a collection of lightweight system daemons that run on Linux. To detect port scans and other suspicious traffic, you use PSAD to analyze the ‘iptables‘ log messages. Visit http://cipherdyne.org/psad/ for more information about PSAD.

Examples of PSAD Alerts

Here are some examples of PSAD email alerts:

Home Network

[psad-alert] DL3 src: 192.168.1.103 dst: ap-op-mars.local
NetRange: 192.168.0.0 – 192.168.255.255
CIDR: 192.168.0.0/16
Comment: This is a computer on the local network.

Google DNS

[psad-alert] DL2 src: google-public-dns-a.google.com dst: ap-op-mars.local
NetRange: 8.0.0.0 – 8.127.255.255
CIDR: 8.0.0.0/9
Comment: Google DNS services are interacting with the local pc.

Local

[psad-alert] DL5 src: thehost.com dst: thehost.com
NetRange: 127.0.0.0 – 127.255.255.255
CIDR: 127.0.0.0/8
Comment: This is the local pc.

How to Ignore IP Ranges in PSAD

Open the PSAD /etc/psad/auto_dl file and add the following lines:

127.0.0.0/8         0;              # Ignore on server calls
192.168.0.0/16      0;          # Ignore home network
8.0.0.0/9           0;               #ignore goodle dns

Restart PSAD when you updated the auto_dl file:

sudo service psad restart

Wrapping up

Adjusting the IP rules for PSAD is quite easy! Need more help? Then read ‘blocking port scan attack‘ by OpenToDo for some brilliant in-depth information.

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