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Karl
Asked: 2018-04-10 10:30:03 +0800 CST

Tap interface using netplan?

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How does one set up tun and tap interfaces on systems that use netplan?

Normally you'd use pre-up in /etc/network/interfaces to call ip tuntap for creating the interface, but I haven't found anything in the netplan docs to do this.

linux-networking

2 Answers

  1. I ran into this problem when upgrading to 18.04 broke my tap based OpenVPN server. It is quite annoying when a headless server just stops working because Ubuntu dropped support for defining bridges in /etc/network/interfaces. There are a few examples already but pretty much you need to create a .yaml file in /etc/netplan that looks something like one of the configs below. Note that you will need the bridge-utils package installed.

    Replace eth0 with the name of your ethernet device. You can find this using ifconfig -a.

    Additionally you can set the MAC address of the bridge using the macaddress: xx:xx:xx:xx:xx:xx option where xx:xx:xx:xx:xx:xx is replaced with the address you want to use.

    /etc/netplan/00-bridge.yaml

    For DHCP:

    network:
  version: 2
  renderer: networkd
  ethernets:
    eth0:
     dhcp4: no
     dhcp6: no
  bridges:
    br0:
      interfaces: [eth0]
      dhcp4: true 
      dhcp6: no

    For a static IP:

    network:
  version: 2
  renderer: networkd
  ethernets:
    eth0:
      dhcp4: no
      dhcp6: no
  bridges:
    br0:
      interfaces: [eth0]
      dhcp4: no
      addresses: [10.0.0.5/24]
      gateway4: 10.0.0.1
      nameservers:
        addresses: [8.8.8.8]
      dhcp6: no
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  2. I didn't find a way to do a tap interface from netplan yaml file, I think you will have to read in deep the reference manual from web page. It is possible the tunnel interface with gretap mode should be a solution. Anyway my advice is use the ip command in a boot script in systemd for example, if you wanna to configure it fast.

    /usr/bin/tap.sh

    #!/bin/bash

ip link add name br0 type bridge;
for i in `seq 0 5`; do
    ip tuntap add name tap$i mode tap;
    ip link set up dev tap$i;
    ip link set tap$i master br0;
done;

    /lib/systemd/system/tap.service

    [Unit]
Description=TAP Interfaces
After=network.target

[Service]
Type=oneshot
User=root
ExecStart=/usr/bin/tap.sh

[Install]
WantedBy=multi-user.target


    $ sudo systemctl enable tap.service
Created symlink /etc/systemd/system/multi-user.target.wants/tap.service → /lib/systemd/system/tap.service.

    Netplan docs: https://netplan.io/reference/#properties-for-device-type-tunnels%3A

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