I've recently installed a Ubiquiti network at home and im identifying every device on my network. My home assistant server is getting hit daily with brute force attempts so im keeping a close eye on my network clients. I plan to deal with this issue in a few weeks after the network build is finished, i still have some more cables to run. Everything on my network is identified on my USG-Pro4 except after a server reboot yesterday my Unraid server's shim-br0 MAC address changed.

Is this standard for this MAC address to change on reboot (asking because i did add some more hardware to the server in the form of another HDD & a 3rd GPU so my VFIO moved about after the hardware installs, not sure if that could have triggered a change)

If the shim-br0 MAC address changing is normal after a server reboot is there any way to make that MAC static so i can easily identify it on the network without doing an "ifconfig" on the server to try hunt down the network after every reboot.

BUMP - Still looking for a solution if anyone has any suggestions 🙃

Edited May 12, 20224 yr by AceRimmer

The shim-br0 interface is derived from the main br0 interface and has the same MAC address as the interface br0.

 

This interface is created when the setting "Host access to custom network" is enabled and is used to circumvent the default protection of Docker.

If you don't have containers which need access to the host, you can disable the setting (default).

 

1 hour ago, bonienl said:

The shim-br0 interface is derived from the main br0 interface and has the same MAC address as the interface br0.

 

This interface is created when the setting "Host access to custom network" is enabled and is used to circumvent the default protection of Docker.

If you don't have containers which need access to the host, you can disable the setting (default).

 

Cool, I'll give disabling it a go and see how I fair out 

I can confirm the mac still changes on every boot with 6.11.   (for shim-br0, which is what the router sees as the main)

is there a way to make the address fixed for the br0 network?

I keep getting a bunch of random mac addresses in my Unifi UDMP and I'd rather label them accurately.

1 minute ago, Ahmad said:

is there a way to make the address fixed for the br0 network?

I keep getting a bunch of random mac addresses in my Unifi UDMP and I'd rather label them accurately.

 

I also have an issue with my Unifi Controller flagging multiple devices are using the same IP because the shim is using the same IP as my Unraid server IP. 

Same here with my UDM Pro. I would like to make it static as well, but I did not find a solution for now. eth0 and br0 have the same physical MAC, but shim-br0 keeps changing on every reboot.

I have the same issue, every reboot MAC changes for my Plex Docker. New devices are not allowed on my network until I manually allow them so No Plex until; I log into router and allow the new MAC. I was not experiencing this (guessing on time frame here) but like pre Sept 2022.

I have the same issue. Looking for a solution. 

Any update on this? Having the same issue with unraid / shim-br0 / udmp

Experiencing the same issue here. I'm facing an issue where my wireguard server (plugin) is not working, and I guess that the "two devices with the same IP" may be the cause. If anyone finds a solution, please share.

8 minutes ago, John Savage said:

Experiencing the same issue here. I'm facing an issue where my wireguard server (plugin) is not working, and I guess that the "two devices with the same IP" may be the cause. If anyone finds a solution, please share.

 

Are you using the VPN manager in settings? I thought the wireguard plugin got depreciated a long time ago. I'm running WG without issues. If you are using the sam check your config against mine. Also assuming you've done your port forwarding on your router as well? 

@AceRimmer thank you for your attention already. I've restarted the router and now the shim-br0 mac address is not showing up in the router's topology screen - which seems like a good thing, I guess.

 

Quote

Are you using the VPN manager in settings? I thought the wireguard plugin got depreciated a long time ago.

Indeed I am. Sorry for the confusion.

 

I have docker containers and VMs I want to access remotely. I'm considering using a wg server in a RPi instead - even though I wouldn't like to maintain a second device.

 

@AceRimmer I contacted the network provider and found out they had migrated me to a CGNAT infrastructure.

He was kind enough to put me back to my old setup - and that was it!

 

Sorry for the trouble, and again, thank you very much for taking the time. God bless you.

Hello, I noticed the same issue on my UNRAIS: shim-br0 has the same IP as eth0.

 

I have activated host access to custom networks because I need it.

 

Any workaround? Is this a bug?

With respect to the original issue regarding the MAC address (data link layer address) of shim-br0 changing on reboot, I suspect the code responsible for assigning the MAC address to shim-br0 can be found in rc.docker here:

     # hack to let containers talk to host
      if [[ $TYPE == br ]]; then
        SHIM=shim-$NETWORK
        if [[ $DOCKER_ALLOW_ACCESS == yes && -n $IPV4 ]]; then
          # create shim interface
          if [[ ! -e $SYSTEM/$SHIM ]]; then
            run ip link add link $NETWORK name $SHIM type $ATTACH mode $MODE   # <-***--THIS LINE CREATES shim-br0
            run ip link set $SHIM up
          fi
          ...
        fi
      else
        ...
      fi
    fi
  done

Based on the ip-link docs, it looks like the ip link add command takes an address argument which can be used to specify the MAC address of the new interface. If the address argument is not used it seems like the kernel may choose a MAC address randomly by following a procedure similar to the one outlined in this stackoverflow post. It may be possible to assign a static MAC address to shim-br0 by supplying one to the ip-link command via the address argument. However, it would need to be generated programmatically using a procedure similar to the kernel to avoid conflicts but deterministically instead of randomly.

@pants Have you tried setting the address argument?