Dummy interface on RHEL¶

With NetworkManager

Create /etc/NetworkManager/dispatcher.d/99-virbr10 and make it executable. This script configures the dummy interface when the virtual bridge is brought up. Use the MAC address that you chose earlier for the virtual bridge.

#!/bin/sh
# See the "DISPATCHER SCRIPTS" section of `man NetworkManager`.
# Remember to make this file executable!
[ "$1" != "virbr10" ] && exit 0
case "$2" in
    "up")
        # Create the dummy interface.
        /sbin/ip link add virbr10-dummy address 52:54:00:7e:27:af type dummy
        # Attach the dummy interface to the bridge.
        /usr/sbin/brctl addif virbr10 virbr10-dummy
        ;;
esac

Without NetworkManager

Create /etc/sysconfig/virbr10-dummy. Use the MAC address that you chose earlier for the virtual bridge.

# echo "MACADDR=52:54:00:7e:27:af" > /etc/sysconfig/virbr10-dummy

Create /etc/systemd/system/dummy@.service with these contents:

# '%i' becomes 'virbr10' when running `systemctl start [email protected]`
# Remember to run `systemctl daemon-reload` after creating or editing this file.

[Unit]
Description=Dummy network interface for %i
After=network.target

[Service]
Type=oneshot
RemainAfterExit=yes
EnvironmentFile=/etc/sysconfig/%i-dummy
ExecStartPre=-/sbin/ip link add %i-dummy address ${MACADDR} type dummy
ExecStart=/usr/sbin/brctl addif %i %i-dummy

[Install]
WantedBy=multi-user.target

Enable and start the service.

# systemctl daemon-reload
# systemctl enable [email protected]
# systemctl start [email protected]

Without NetworkManager and without systemd

Warning

This requires loading the dummy kernel module, which creates an interface called dummy0. When following instructions later in this guide, remember that the interface is called dummy0, not virbr10-dummy, and amend the commands accordingly.

Create /etc/sysconfig/network-scripts/ifcfg-dummy0. Use the MAC address that you chose earlier for the virtual bridge.

DEVICE=dummy0
MACADDR=52:54:00:7e:27:af
NM_CONTROLLED=no
ONBOOT=yes
TYPE=Ethernet
BRIDGE=virbr10
IPV6INIT=no

Load the dummy module.

# modprobe dummy numdummies=1
# echo "dummy" > /etc/modules-load.d/dummy.conf
# echo "options dummy numdummies=1" > /etc/modprobe.d/dummy.conf

If using Red Hat Enterprise Linux 6, create an executable file called /etc/sysconfig/modules/dummy.modules with the following contents:

#!/bin/sh
/sbin/modprobe dummy numdummies=1