kvm bridge issue

Help with issues regarding installation of Debian
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Author
jhmnieuwenhuis
Posts: 1
Joined: 2021-07-29 15:08

kvm bridge issue

#1 Post by jhmnieuwenhuis »

I installed kvm on my debian laptop. it has a wired ethernet conection.
I created some debian guests using the default ( natted) network. all work fine.
Then i created a bridged network and created a guest using the bridged network.
It gets a ip4 address in the range of my home network so that looks good.
After installation i can connect to the new guest. i can also ping it and ssh into it from other hosts in my network.

The problem is that on the guest i can not ping out so ping google.com does not return anything and stays active...
Looks like dns resolving is not working.
No firewall.

Also apt update des not work, also due to dns issues.

From the host ping google.com works fine.

The host uses the following interfaces file :

auto lo
iface lo inet loopback

# The primary network interface
auto enp0s25

#make sure we don't get addresses on our raw device
iface enp0s25 inet manual
iface enp0s25 inet6 manual

#set up bridge and give it a static ip
auto br0
iface br0 inet static
address 192.168.178.22
netmask 255.255.255.0
network 192.168.178.0
broadcast 192.168.178.255
gateway 192.168.178.1
bridge_ports enp0s25
bridge_stp off
bridge_fd 0
bridge_maxwait 0
dns-nameservers 8.8.8.8

#allow autoconf for ipv6
iface br0 inet6 auto
accept_ra 1

Any ideas what could be the issue here ??
I tried and googled for several days, but can not get it working.

Regards
Hans

jmgibson1981
Posts: 87
Joined: 2015-06-07 14:38

Re: kvm bridge issue

#2 Post by jmgibson1981 »

Eliminate variables. Unless you need all of those settings remove them and start as minimal as possible. Try this.

Code: Select all

auto lo
iface lo inet loopback

auto br0
iface br0 inet static
  address 192.168.178.22
  netmask 255.255.255.0
  gateway 192.168.178.1
  dns-nameservers 8.8.8.8
  bridge_ports enp0s25
This can also work to combine the netmask and address

Code: Select all

address 192.168.178.22/24
And of course make sure the bridge-utils package is installed.

One has to be careful with guides found via random search. They often have options and other things that you may not need. The simpler it is the better. Then if you need certain things you can add them as needed. The less lines and features, the easier to track a problem.

If you don't need a static ip on the host then it gets even simpler.

Code: Select all

auto lo
iface lo inet loopback

auto br0
iface br0 inet dhcp
  bridge_ports enp0s25

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