CONTRIBUTION: bridge interface for kvm or virt-manager

[Member techore]

A default bridge, virbr0, is created by virt-manager and the user after its initial launch or using virsh. This “default” bridge is fine for most use cases but a bridge bound to physical interface may be wanted or needed for other use cases.

This solution is but one of half-dozen solution to create a bridge, but I prefer to manage the bridge directly in /etc/network/interfaces.

1. Install package bridge-utils
2. Identify physical interface (port), eth0
3. Determine bridge name, bridge0
4. If using connman, update /etc/connman/main.conf blacklist to include eth0 and bridge0
5. Update /etc/network/interfaces to define eth0 and bridge0
6. Reboot

After reboot, virtual machines may be configured to use bridge0.

I have an install script that you may find useful as a reference. Recommend checking the git repo for updates.

git repo: https://gitlab.com/techore/antix-dwm/-/blob/main/install/inst-bridge.sh

#!/usr/bin/env bash
# Location: /usr/local/src/antix-dwm/install/inst-bridge.sh
# Dependency: bridge-utils
# Description: update /etc/network/interfaces to create bridge
#   sourced by inst-virtmanager.sh
# Usage: sudo inst-bridge.sh

if test $EUID -gt 0; then
    printf "\n    Must be root or using sudo!\n\n"
    exit 1
fi

# Bridge
# Using bridge instead of virbr to distinguish from virsh created bridges.
read -p "Enter bridge name [bridge0]: " BRIDGE
BRIDGE=${BRIDGE:-bridge0}
printf "\n=========>  Assign $BRIDGE as bridge name.\n\n"
read -p "ENTER to continue or CTRL+c to exit."
printf "\n"

# Bridge port
read -p "Enter bridge port name [eth0]: " BPORT
BPORT=${BPORT:-eth0}
printf "\n=========>  Assign $BPORT as bridge port.\n\n"
read -p "ENTER to continue or CTRL+c to exit."
printf "\n"

# Install dependency
printf "\n========>  Install bridge-utils for bridge support.\n\n"
apt -y install bridge-utils

# Backup files
# Backup main.conf
printf "\n========>  Backup /etc/connman/main.conf.\n\n"
cp /etc/connman/main.conf "/etc/connman/main.conf.$(date '+%Y%m%d%H%M').bak"
ls -l /etc/connman/*.bak

# Backup interfaces
printf "\n========>  Backup /etc/network/interfaces.\n\n"
cp /etc/network/interfaces "/etc/network/interface.$(date '+%Y%m%d%H%M').bak"
ls -l /etc/network/*.bak

# Update /etc/connman/main.conf to blacklist bridge and bridge port
printf "\n  Add $BRIDGE and $BPORT to connman blacklist\n\n"
# Blacklist bridge
sed -i 's/^# NetworkInterfaceBlacklist/NetworkInterfaceBlacklist/' /etc/connman/main.conf
if ! grep -q "^NetworkInterfaceBlacklist.*$BRIDGE" /etc/connman/main.conf; then
	sed -i "s/^NetworkInterfaceBlacklist = /NetworkInterfaceBlacklist = $BRIDGE,/" /etc/connman/main.conf
fi
# Blacklist bridge port
if ! grep -q "^NetworkInterfaceBlacklist.*$BPORT" /etc/connman/main.conf; then
	sed -i "s/^NetworkInterfaceBlacklist = /NetworkInterfaceBlacklist = $BPORT,/" /etc/connman/main.conf
fi
grep NetworkInterfaceBlacklist /etc/connman/main.conf

# Update /etc/network/interface
printf "\n  Configure $BRIDGE and $BPORT in /etc/network/interfaces\n\n"
# $BPORT
if ! grep -q "$BPORT" /etc/network/interfaces; then
	printf "\nauto $BPORT\niface $BPORT inet manual\n" >> /etc/network/interfaces
else
	printf "\n=========>  $BPORT found in /etc/network/interfaces!"
	printf "\n=========>  Manual update for $BPORT may be needed.\n\n" 
fi
# $BRIDGE
if ! grep -q "$BRIDGE" /etc/network/interfaces; then
	printf "\nauto $BRIDGE\niface $BRIDGE inet dhcp\n    bridge_ports $BPORT\n    bridge_stp off\n    bridge_fd 0\n    bridge_maxwait 0\n " >> /etc/network/interfaces
else
	printf "\n=========>  $BRIDGE found in /etc/network/interfaces!"
	printf "\n=========>  Manual update for $BRIDGE may be needed.\n\n" 
fi
cat /etc/network/interfaces

printf "\n\n=========>  Done!\n\n"

@olsztyn, hope this helps.

• This topic was modified 2 weeks ago by techore.
• This topic was modified 1 week, 6 days ago by techore.
• This topic was modified 1 week, 6 days ago by techore.

[Member olsztyn]

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techore wrote:

@olsztyn, hope this helps.

Thank you @techore for developing this process. Greatly appreciate.
Hopefully I will find some time before my travel to Europe to implement following your guide.

Live antiX Boot Options (Previously posted by Xecure):
https://antixlinuxfan.miraheze.org/wiki/Table_of_antiX_Boot_Parameters

[Member techore]

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and, I meant to provide the resulting /etc/network/interfaces file.

$ cat /etc/network/interfaces
#------------------------------------------------------------------------------
# /etc/network/interfaces
#
# interfaces(5) file used by ifup(8) and ifdown(8)
# Used by ceni but not by connman
#------------------------------------------------------------------------------

auto lo
iface lo inet loopback

auto eth0
iface eth0 inet manual

auto bridge0
iface bridge0 inet dhcp
    bridge_ports eth0
    bridge_stp off
    bridge_fd 0
    bridge_maxwait 0

[Member techore]

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I wish that I could edit my original post..

Step 4 is updated to blacklist virtual machine nic (vnet) from connman.

4. If using connman, update /etc/connman/main.conf blacklist to include vnet, eth0, and bridge0

Shell script inst-bridge.sh updated on gitlab.com

If you do not blacklist the virtual machine network interfaces, connman will attempt to manage them and creates additional default and 0.0.0.0 gateways resulting with the virtual machines working but host routing breaks.

Testing continues. I am confident there will further issues.. 😀

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