Skip to content

Flareoff is a stateful software firewall implemented as a Loadable Kernel Module (LKM)

License

Notifications You must be signed in to change notification settings

swingcake/flareoff

Folders and files

NameName
Last commit message
Last commit date

Latest commit

 

History

7 Commits
 
 
 
 
 
 
 
 
 
 
 
 

Repository files navigation

Flareoff - Firewall as Loadable Kernel Module

Flareoff is a stateful software firewall implemented as a Loadable Kernel Module (LKM). Flareoff provides network security by filtering incoming and outgoing network traffic based on a set of user-defined rules.

Loadable Kernel Modules are kernel extensions that can be loaded into operating system kernel dynamically.

Working

main.c resides in the kernel and hooks itself with the existing netfilter hooks, specifically the PRE_ROUTING hook. In the topology that is created, gateway is then placed at a position such that all the traffic to and from outside the LAN flows through this gateway.

The 'main' module inspects every packet and based on the rules provided, makes the decision of whether to accept the packet or to drop it.

Following are the rules 'main' module implements:

  • Block all unsolicited ICMP packets coming in from outside except the ones going to the web-server. However, the local hosts should be able to ping outside.
  • Block all SSH attempts from outside.
  • Block port 80 (HTTP) access from outside except for the web-server and test that an internal website on a local host is only accessible from inside.

Setup

Provided is main.c and a Makefile.

Pre-requisites for successful build:
sudo apt-get install linux-headers-$(uname -r) build-essential

  1. Run the make command inside the directory you have kept these files
    make
  2. Successful build will generate main.ko which is the kernel module
  3. Now, load this module directly in the kernel
    sudo insmod ./main.ko
  4. To see which packets pass the filter and which are dropped, use
    sudo tail -f /var/log/kern.log
  5. To unload the kernel module,
    sudo rmmod main

Licensing and Contribution

Flareoff is an open-source software and is licensed under the GNU General Public License v3.0. Anyone interested is free to contribute to the project.

About

Flareoff is a stateful software firewall implemented as a Loadable Kernel Module (LKM)

Topics

Resources

License

Stars

Watchers

Forks

Releases

No releases published

Packages

No packages published