Simple destination TCP port blocker

Usage:

Build and load the module:

git clone https://github.com/amkgi/linux-kernel-portblocker
cd linux-kernel-portblocker
make
sudo insmod port_blocker.ko tcp_port=22

The default port is 80.

Testing:

curl ya.ru

Monitoring:

sudo dmesg -w | grep port_blocker

Unload the module:

sudo rmmod port_blocker

Links:

1. The Linux Kernel Module Programming Guide
2. Linux Kernel Communication — Netfilter Hooks

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Tested on kernel 6.1.50-1-generic in Astra Linux 1.7.5.