How to setup a bridge with network-manager?

Question

I'm in a situation where I (think to) know how to setup a bridge and WiFi in system configuration files, but want to figure out how to use network-manager (because it's more comfortable regarding switches between WiFi networks, VPN provfiles, etc.) and because it apparently supports creation of bridges (based on its configuration GUI controls).

The thing is that creating a bridge and a slave doesn't have any effect on the list of available network connection, so my question is what is supposed to happen after creating a bridge br0 which enslaves the ethernet interface eth0 which is managed by network-manager and is configured through DHCP. Obviously something has to change which I don't see or the bridge creation function wouldn't make sense.

Mixing system configuration and network-manager seems no option because network-manager can't control interfaces which are controlled by/listed in the system configuration.

I'm using Ubuntu 16.10.

Answer 1

After searching and experimenting, I also can't find a way to use the network-manager UI to activate bridges that are set up using the network-manager UI (tested on 16.04 LTS).

However, after you set up the bridge interface in network-manager, you can use the nmcli command line tool to switch it on like so:

$ nmcli connection show
NAME                              UUID                                  TYPE             DEVICE 
New bridge                        fcaca251-7425-4a09-af4b-9cdf022d1c8c  bridge           br0    
Ethernet (br0 slave)              2deb668a-dce4-4295-af7b-529f34993aac  802-3-ethernet   --   
Auto Ethernet                     e02fd57f-e0ef-4391-94c4-c886975d71e6  802-3-ethernet   --     

$ nmcli connection up fcaca251-7425-4a09-af4b-9cdf022d1c8c
Connection successfully activated (master waiting for slaves) (D-Bus active path: /org/freedesktop/NetworkManager/ActiveConnection/11)
Connection successfully activated (master waiting for slaves) (D-Bus active path: /org/freedesktop/NetworkManager/ActiveConnection/11)

$ nmcli connection up 2deb668a-dce4-4295-af7b-529f34993aac
Connection successfully activated (D-Bus active path: /org/freedesktop/NetworkManager/ActiveConnection/12)

I can't directly answer your question of, "What is supposed to happen?", but this avoids having to manually use brctl or edit /etc/network/interfaces, because you're doing everything through Network Manager (even if it's not all through the UI).