farewell

internetShare.md

Magical Linux internet sharing: The Tutorial

The following tutorial assumes that you want to provide the interwebs to a PC connected via eth0 to your host, and that your host is connected to the world via wlan0.

1. Set up the local IP address

# ifconfig eth0 192.168.250.1

or, if you're using ip:

# ip a a 192.168.250.1/24 dev eth0

2. Enable IPv4 forwarding

# sysctl -w net.ipv4.ip_forward=1

3. Forward packets via iptables

# iptables -A FORWARD --in-interface eth0 -j ACCEPT
# iptables --table nat -A POSTROUTING --out-interface wlan0 -j MASQUERADE

4. Launch dnsmasq

# dnsmasq -F 192.168.250.2,192.168.250.10,12h -i eth0 -d

4.1 If dnsmasq is not available, set up IP on the second machine by hand

# ifconfig eth0 192.168.250.2
# route add default gw 192.168.250.1

...or, without ifconfig/route...

# ip a a 192.168.250.2/24 dev eth0
# ip r a default via 192.168.250.1

5. ???
6. Profit!

usbShare.sh

#!/bin/bash
# Working example script that shares internet from your Android phone via USB tethering through your PC to Ethernet.
# Tested on Void linux and quirky network card (note that we need to bring the iface down before bringing it up!)

ifconfig eth0 down
ifconfig eth0 0.0.0.0
sysctl -w net.ipv4.ip_forward=1
iptables -A FORWARD --in-interface eth0 -j ACCEPT
iptables --table nat -A POSTROUTING --out-interface usb0 -j MASQUERADE
ifconfig eth0 192.168.250.1
ifconfig eth0 up
dnsmasq -F 192.168.250.2,192.168.250.10,12h -i eth0 -d

Hey, casual onlooker that's maintaining their own network as a hobby over here.

What would be the best way to do that automatically, in your opinion? (as in; not using a systemd service to run this bash script)

Hey, casual onlooker that's maintaining their own network as a hobby over here.

What would be the best way to do that automatically, in your opinion? (as in; not using a systemd service to run this bash script)

1. Invoke iptables-save (and you may need to redirect the output to /etc/iptables/rules.v4 depending on your OS).

2. Replace your /etc/dnsmasq.conf with the following:

port=53

except-interface=wlan0
dhcp-range=interface:eth0,192.168.250.10,192.168.250.254,24h

3. Add net.ipv4.ip_forward=1 to your /etc/sysctl.conf.

4. And for the last step, you need to somehow bring up eth0 on boot and set the static IP. I'd go with either /etc/rc.local and adding a few ifconfig commands in there, or using /etc/network/interfaces and configuring it over there - but you may go as far as to create a static IP NetworkManager config if you so desire.

Thanks a lot, really needed a run-down like this because I kept doing all of these steps alongside other "contradictory" steps that just broke the entire thing.