simple-firewall-netfilter-lkm

Using Linux Kernel Modules (LKM) and Netfilter to implement a packet filtering module. This module will filter packets based on hard coded rules. Effectively creating a simple firewall.

Environment is a NAT network with two machines on it:

• Machine A (has firewall installed on it)
• Machine B

Firewall Rules implemented

1. Outbound telnet traffic from Machine A to Machine B.
2. Inbound telnet traffic to Machine A from Machine B.
3. Outbound SSH (Secure Shell) traffic from Machine A to Machine B.
4. Inbound SSH traffic to Machine A from Machine B.
5. Access from Machine A to a specific external website.

Simple Install

Uses a bash script to run the commands

$ make
$ sudo ./reload.sh

Manual Install

Build

$ make

Install module into the Kernel

$ sudo insmod myfirewall.ko

Check that module was loaded

$ lsmod | grep myfire

To check log for the kernal files

$ sudo dmesg | tail -10

To uninstall Module

$ sudo rmmod myfirewall