Since I have some Rasperry PI’s which do not have a WAN connection because they are in an autonomous LAN or just do not have a WLAN module. From time to time I want to do some upgrades. So I need a connection between the LAN containing my PI’s and the WAN.
Same problem when playing around with a new PI without a WLAN configuration or dongle.
The Router
Easiest way to give them connection to WAN is to use my linux workstation/laptop as router. All to do is to run following script on my laptop
#!/bin/bash sudo sysctl -w net.ipv4.ip_forward=1 sudo iptables -A FORWARD -o wlp2s0 -i enx847beb52b12b -m conntrack --ctstate NEW -j ACCEPT sudo iptables -A FORWARD -o wlp2s0 -s 172.16.100.0/24 -m conntrack --ctstate NEW -j ACCEPT sudo iptables -t nat -A POSTROUTING -o wlp2s0 -j MASQUERADE
In this case:
- wlp2s0 is the target interface which has a connection to WAN
- enx847xxx is the LAN which should be routed
- 172.16.100.0/24 is the network on LAN which is allowed to be routed
To be routed
On the client just set default gatway to ip address of the linux station.
If you do something like this there is already a static IP set on the client.
In my case on raspberry I just set static ip in ‘/etc/network/interfaces’
iface eth0 inet static address 172.16.100.21 netmask 255.255.255.0 network 172.16.100.0 broadcast 172.16.100.255 gateway 172.16.100.1
where 172.16.100.1 is the ip of my routing pc.
The original file normally has just one line for eth0 like
iface eth0 inet dhcp
After changing ‘/etc/network/interfaces’ I had to reboot my pi, however ‘sudo systemctl restart networking.service’ did not help.
