k210-sdk-stuff/linux/README.md
Wladimir J. van der Laan d9750dcf73 Add k210 linux utilities
2020-02-21 15:42:04 +00:00

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esptun
======
A tool to tunnel IP packets over UDP over WIFI through an UART connected to a ESP8285 with the
standard AT firmware.
Usage
-----
esptun <ifname> <uart> <ssid> <passwd> <host> <port>
This will create tun interface `ifname`. Then, with the with the ESP WIFI
device on `uart` it connects to the AP `ssid` with password `passwd`.
It creates a UDP over IP tunnel with the other endpoint `host:port`.
The new tun device will not be configured, use the `ip` utility to assign an
IP address and switch the interface on.
For example:
/root/esptun tun0 /dev/ttyS1 "accesspointname" "secretpassword" 192.168.122.21 23232
/sbin/ip addr add 10.0.1.2/24 dev tun0
/sbin/ip link set tun0 up
/sbin/ip route add default via 10.0.1.1 dev tun0
Host side
---------
On the other endpoint the tunnel is expected to be a host running `socat` or similar to unwrap
the tunnel. For example:
sudo socat UDP:192.168.2.127:23232,bind=192.168.122.21:23232 \
TUN:10.0.1.1/24,tun-name=tundudp,iff-no-pi,tun-type=tun,su=$USER,iff-up
Optionally, enable forwarding and masquerading:
sudo iptables -t nat -F
sudo iptables -t nat -A POSTROUTING -o ens3 -j MASQUERADE
echo 1 | sudo tee /proc/sys/net/ipv4/ip_forward
Linux kernel
------------
Until there is a proper solution, you can use the following kernel branch
to get the UART working on Kendryte K210 under Linux:
https://github.com/laanwj/linux/tree/kendryte-5.6-rc1-wifi
This is a hack that configures the FPIOA and GPIOHS manually, and configures UART1
from the device tree.
To enable TUN/TAP, enable the following kernel settings:
```
CONFIG_NET=y
CONFIG_INET=y
CONFIG_TUN=y
```
While building the root filesystem, make sure you enable at least `ip` and `ping`
(and possibly other network tools) for busybox.
Author
------
Copyright (c) 2020 W.J. van der Laan
Distributed under the MIT software license,