Open main menu

USB Internet

Revision as of 14:01, 3 March 2020 by Afontain (talk | contribs) (→‎Ubuntu/Arch: change the subtitle to Ubuntu/Arch/Alpine)
(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)

You can enable internet through the USB cable when WiFi doesn't work yet on your device. For this to work you set your host machine as gateway for your phone and let your host machine do network address translation for the phone.

On your phone:

$ sudo route add default gw
$ echo nameserver | sudo tee /etc/resolv.conf
Substitute for your own internal DNS server if you want.

To make the configuration persistent after reboot do:

$ echo 'route add default gw' | sudo tee /etc/local.d/usb_internet.start
$ sudo chmod +x /etc/local.d/usb_internet.start
$ sudo rc-update add local
$ #disable it if you plug the USB cable out and want to use WiFi, because it can interfere with routing (packets would try to use the USB networking, even though it's disconnected)

On the host machine:

$ sudo sysctl net.ipv4.ip_forward=1
$ sudo iptables -P FORWARD ACCEPT
$ sudo iptables -A POSTROUTING -t nat -j MASQUERADE -s

This will enable IPv4 forwarding on your host machine which basically lets it function as a router. The postrouting command will make the kernel on the host translate the packets between the phone network and your normal network on the host machine.

$ sudo sysctl net.ipv4.ip_forward=1
$ sudo firewall-cmd --get-active-zone 
$ sudo nmcli connection modify ethX_other external
$ sudo nmcli connection modify ethX_to_phone internal
$ sudo firewall-cmd --get-active-zone 
$ sudo firewall-cmd --zone=external --add-masquerade
$ sudo firewall-cmd --zone=external --list-all
$ sudo firewall-cmd --zone=internal --list-all

Use the --permanent and --reload options for a persistent configuration.[1]

You can now verify the internet connection on your phone by pinging something. If this does not work it means you need to compile the kernel with USB_ETH setting enabled in menuconfig.