Check open ports every ...

Shell Programming and Scripting
1

Hello, i need a script (bash type maybe?..), which would check open ports on 127.0.0.1 and then compare open ports with "registered/allowed" port list and try to kill the program who uses unregistered ports. It would be great that script would be started lets say every 5 or 10 minutes.

You see i would like to have some kind of script which would allow me to control other users that they don't leave their psybnc, eggdrops and so on.

Thanks...

2

You could use the 'lsof' command to check what process is listening on a particular port, but it is a bit slow so you wont be able to run the script every 5 minutes (all the ports wont be scanned by then).

3

Provided you have netcat installed, this should run pretty quickly.

for port in {1..65536}; do
    nc -zv 127.0.0.1 $port 2>&1
done | grep open

Netstat will also tell you what programs have open listening tcp ports. On a linux system, it would go something like this:

netstat -l -t -p
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