Debian 10 bridge disappear after reboot

bridgedebianlinux-networkingnetworking

I created a bridge in my Debian 10 router like this
# brctl addbr br0 after that I add network interface on my bridge # brctl addif br0 eno1

brctl show
bridge name bridge id       STP enabled interfaces
br0     8000.0030bdb2810d   no      eno1

My /etc/network/interfaces look like this 

# The loopback network interface
auto lo
iface lo inet loopback

# Set up interfaces manually, avoiding conflicts with, e.g., network manager

iface eno1 inet manual

# Bridge setup
auto br0

iface br0 inet dhcp
      bridge_ports eno1

Everything works well, but If I reboot my router, brctl show returns empty result.
In my syslog I have this strange line :
bridge: filtering via arp/ip/ip6tables is no longer available by default. Update your scripts to load br_netfilter if youd nedd this is that normal ?
PS : I disabled ipv6 in sysctl.conf with this line net.ipv6.conf.all.disable_ipv6 = 1

What I need to do to have my bridge when my router reboot?

Best Answer

The Debian wiki mentions what may be the same problem, for Stretch and Buster. If your system has the file /etc/network/interfaces.d/setup (mine does not) you could try removing it.

Otherwise, I like your idea of adding the bridge on startup. You could try in /etc/network/interfaces:

auto br0
iface br0 inet dhcp
  pre-up brctl addbr br0 && brctl addif br0 eno1
  post-down brctl delif br0 eno1 && brctl delbr br0

The post-down line is included for symmetry and to make sure that the pre-up line doesn't fail (which would abort ifup br0) if br0 is ever taken down and back up.

A safer way is probably:

auto br0
iface br0 inet dhcp
  pre-up { brctl addbr br0 && brctl addif br0 eno1; } || true

where the || true prevents the pre-up command from ever failing and aborting ifup br0. Ref: https://manpages.debian.org/buster/ifupdown/interfaces.5.en.html

I don't think you need to worry about the arp/ip/ip6tables filtering warning you're seeing, unless you need such filtering. The warning is unrelated to your current problem.

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