https://github.com/seantywork/gpiosk
GPIO based Linux netdevice kernel module
https://github.com/seantywork/gpiosk
gpio kernel linux networking raspberry-pi
Last synced: 2 months ago
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GPIO based Linux netdevice kernel module
- Host: GitHub
- URL: https://github.com/seantywork/gpiosk
- Owner: seantywork
- License: gpl-2.0
- Created: 2025-06-21T02:28:21.000Z (12 months ago)
- Default Branch: main
- Last Pushed: 2025-11-17T01:12:38.000Z (7 months ago)
- Last Synced: 2025-11-17T01:20:45.299Z (7 months ago)
- Topics: gpio, kernel, linux, networking, raspberry-pi
- Language: C
- Homepage:
- Size: 3.89 MB
- Stars: 3
- Watchers: 0
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
# gpiosk
GPIO based Linux netdevice kernel module
- [what is this?](#what-is-this)
- [specification](#specification)
- [documentation](#documentation)
- [how to](#how-to)
- [xdp feature](#xdp-feature)
# what is this?
This kernel module is no different from a plain old Linux networking interface...\
except it uses GPIO to send and receive data
### interface info
```shell
# on rpi1
# ip a
15: geth0: mtu 1500 qdisc pfifo_fast state UNKNOWN group default qlen 1000
link/ether 47:45:54:48:30:36 brd ff:ff:ff:ff:ff:ff
inet 10.10.0.1/24 scope global geth0
valid_lft forever preferred_lft forever
inet6 fe80::4545:54ff:fe48:3036/64 scope link
valid_lft forever preferred_lft forever
```
```shell
# on rpi2
# ip a
1: geth0: mtu 1500 qdisc pfifo_fast state UNKNOWN group default qlen 1000
link/ether 47:45:54:48:30:33 brd ff:ff:ff:ff:ff:ff
inet 10.10.0.2/24 scope global geth0
valid_lft forever preferred_lft forever
inet6 fe80::4545:54ff:fe48:3033/64 scope link
valid_lft forever preferred_lft forever
```
### example: tcp communication using nc
```shell
# on rpi2
$ nc -l 10.10.0.2 9999
helllo
echo
bye
```
```shell
# on rpi1
$ nc 10.10.0.2 9999
helllo
echo
bye
```
# specification
So far, I only tested it on my raspberry pi 4b with spec below
```shell
# lscpu
Architecture: aarch64
CPU op-mode(s): 32-bit, 64-bit
Byte Order: Little Endian
CPU(s): 4
On-line CPU(s) list: 0-3
Vendor ID: ARM
Model name: Cortex-A72
Model: 3
Thread(s) per core: 1
Core(s) per cluster: 4
Socket(s): -
Cluster(s): 1
Stepping: r0p3
CPU(s) scaling MHz: 33%
CPU max MHz: 1800.0000
CPU min MHz: 600.0000
BogoMIPS: 108.00
Flags: fp asimd evtstrm crc32 cpuid
```
```shell
# uname -a
Linux raspberrypi 6.12.25+rpt-rpi-v8 #1 SMP PREEMPT Debian 1:6.12.25-1+rpt1 (2025-04-30) aarch64 GNU/Linux
```
# documentation
Refer to the following [how to](#how-to) section
~~- [version 1.0](https://medium.com/@seantywork/gpiosk-introducing-my-gpio-based-linux-socket-kernel-module-bba2d114236e)~~
# how to
1. physical wiring
- blueprint
- actual
2. build
```shell
make
```
3. insmod
```shell
# hwid should be an interger ranging from 1 to 9
# and should be set differently for each host
# because `gpiosk` module uses it to set hw addr
sudo insmod gpiosk.ko hwid=$HWID
```
# xdp feature
### install xdp-tools
```shell
cd xdp-prog
./install.sh
```
### build sample xdp programs
```shell
cd xdp-prog
make
```
### example: allowing tcp communication
```shell
# on rpi2
$ cd xdp-prog
$ sudo xdp-loader load -m native -s xdp_prog geth0 "xdp_pass.o"
$ nc -l 10.10.0.2 9999
# on rpi2, terminal 2
sudo dmesg -wH
```
```shell
# on rpi1
$ nc 10.10.0.1 9999
```
```shell
# on rpi2, terminal 2
[ +0.000035] entered xmit
[ +0.000004] entered hw tx
[ +0.000003] eth src: 47:45:54:48:30:33
[ +0.000005] eth dst: 47:45:54:48:30:36
[ +0.000004] src: 0a0a0002:09999
[ +0.000004] dst: 0a0a0001:37512
[ +0.048151] exiting xmit
[ +0.000006] npackets smaller than budget
[ +0.000004] napi complete
[ +0.000003] polling end
[ +0.223525] napi interrupt
[ +0.000010] napi receive
[ +0.000002] napi interrupt end
[ +0.000009] polling
[ +0.000005] geth: XDP_PASS # <------- here you can see the traffic is allowed by the sample program
```
```shell
# unload
$ sudo xdp-loader unload geth0 -a
```
### example: blocking tcp communication
```shell
# on rpi2
$ cd xdp-prog
$ sudo xdp-loader load -m native -s xdp_prog geth0 "xdp_drop.o"
$ nc -l 10.10.0.2 9999
# on rpi2, terminal 2
sudo dmesg -wH
```
```shell
# on rpi1
$ nc 10.10.0.1 9999
```
```shell
# on rpi2, terminal 2
[Sep15 01:48] napi interrupt
[ +0.000013] napi receive
[ +0.000003] napi interrupt end
[ +0.000013] polling
[ +0.000008] geth: XDP_DROP # <---------- here you can see the traffic is blocked by the sample program
```
```shell
# unload
$ sudo xdp-loader unload geth0 -a
```