https://github.com/jakubvojvoda/linux-firewall
Simple Linux firewall using Netfiler
https://github.com/jakubvojvoda/linux-firewall
c firewall kernel netfilter netfilter-hook packet-processing
Last synced: 27 days ago
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Simple Linux firewall using Netfiler
- Host: GitHub
- URL: https://github.com/jakubvojvoda/linux-firewall
- Owner: JakubVojvoda
- License: mit
- Created: 2016-05-07T11:13:17.000Z (about 9 years ago)
- Default Branch: master
- Last Pushed: 2016-09-22T13:22:11.000Z (over 8 years ago)
- Last Synced: 2025-05-14T04:35:43.442Z (27 days ago)
- Topics: c, firewall, kernel, netfilter, netfilter-hook, packet-processing
- Language: C
- Homepage:
- Size: 10.7 KB
- Stars: 1
- Watchers: 2
- Forks: 1
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# Linux Firewall
Implementation of a simple Linux Firewall using Netfilter for packet manipulation. The source code is licensed under MIT license (see [LICENSE]) and you should use it (insert builded kernel module) ONLY at your OWN RISK.
### User space application
Command line application that communicates with a given kernel module. The possible command line arguments are following:
* argument `-a RULE`
* add specific rule to the filtering logic
* `RULE`: `NUMBER ACTION PROTOCOL FROM address TO address src dst`, where `address` is `IP` or `ANY`, `src` is optional (`SRCPORT NUMBER`) and `dst` is optional destination port (`DSTPORT NUMBER`).
* argument `-f FILTER-FILE`
* add all rules defined in the file `FILTER-FILE` to the filtering logic
* argument `-d RULE-ID`
* delete rule from the filtering logic
* `RULE-ID` is a rule identificator
* argument `-p`
* print list of rules defined in the module
### Kernel module
Implementation of the kernel modul for Linux in version compatible with kernel version 3.13.
### Provided files
The repository contains files
* `pdsfw.c` - kernel module
* `pdscli.c` - user space application
* `lexer.l` - lexical analyzer ([flex]) input
* `parser.y` - parser ([bison]) input
* `Makefile`
Using the `make` command it is possible to build user space application and kernel module. The kernel module can be loaded using command `insmod pdsfw.ko` (at your own risk !!!) and removed using command `rmmod pdsfw`. In case of unexpected problems (eg. failure due to lack of memory, ...), the state is written in log file which can be displayed using command `dmesg`.
### References
* [How to Write a Linux Firewall]
* [Course: Data Communications, Computer Networks and Protocols]
[How to Write a Linux Firewall]: http://www.roman10.net/a-linux-firewall-using-netfilter-part-1overview/
[Course: Data Communications, Computer Networks and Protocols]: http://www.fit.vutbr.cz/study/course-l.php.en?id=11584
[flex]: http://flex.sourceforge.net/
[bison]: https://www.gnu.org/software/bison/
[LICENSE]: https://github.com/JakubVojvoda/linux-firewall/blob/master/LICENSE