Create Dummy Network Interface Using Network Manager

Sometimes we need a virtual network interface for testing purposes—without requiring physical hardware. A dummy interface can help with tasks like simulating network configurations or testing firewall rules. Having a dummy interface is handy for a variety of network experiments and tests. Here’s how we can easily create one that persists across reboots using NetworkManager’s command-line tool (nmcli).

Run the following command to add a new dummy interface called dummy0:

sudo nmcli connection add type dummy ifname dummy0 con-name dummy0

Set a static IPv4 and IPv6 address to the interface:

sudo nmcli connection modify dummy0 ipv4.addresses 10.10.10.10/24 ipv4.method manual
sudo nmcli connection modify dummy0 ipv6.addresses 2001:db8::10/64 ipv6.method manual

Activate the connection:

sudo nmcli connection up dummy0

After setup, we can confirm that dummy0 is up and configured:

ip a show dummy0

Typical output:

4: dummy0: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN group default qlen 1000
    link/ether 3a:9d:f3:a4:b4:66 brd ff:ff:ff:ff:ff:ff
    inet 10.10.10.10/24 brd 10.10.10.255 scope global noprefixroute dummy0
       valid_lft forever preferred_lft forever
    inet6 2001:db8::10/64 scope global noprefixroute
       valid_lft forever preferred_lft forever
    inet6 fe80::d224:a78b:6aa6:e6b/64 scope link noprefixroute
       valid_lft forever preferred_lft forever