Help with setting up bridging
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  1. #1
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    Help with setting up bridging

    Hi,
    I'm trying to set up a bridge to use with KVM but I'm not having any luck.
    I've followed the guide on server world
    but I cannot get the bridge to work.
    This is what I've done:
    Code:
    nmcli connection add type bridge autoconnect yes con-name br0 ifname br0
    nmcli connection modify br0 ipv4.addresses 192.168.1.88/24 ipv4.method manual
    nmcli connection modify br0 ipv4.gateway 192.168.1.251
    nmcli connection modify br0 ipv4.dns 192.168.1.1,192.168.1.2
    nmcli connection modify br0 ipv4.dns-search domain.local
    nmcli connection add type bridge-slave autoconnect yes con-name enp031f6-bridge-slave ifname enp031f6 master br0
    nmcli con up br0
    which gives me this:
    Code:
    #nmcli con show
    NAME                   UUID                                  TYPE      DEVICE    
    Wired connection 1     84a07438-4ab5-4009-bc34-bed3fb765761  ethernet  enp0s31f6 
    br0                    3b7f7787-b2d7-4405-ae2c-50e7dd89da34  bridge    br0       
    enp031f6-bridge-slave  f74faf38-83e7-464b-b3a4-76c096436e28  ethernet  -- 
    
    #ip a
    1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
        link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
        inet 127.0.0.1/8 scope host lo
           valid_lft forever preferred_lft forever
        inet6 ::1/128 scope host 
           valid_lft forever preferred_lft forever
    2: enp0s31f6: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
        link/ether 30:9c:23:74:e0:e1 brd ff:ff:ff:ff:ff:ff
        inet 192.168.1.88/24 brd 192.168.106.255 scope global noprefixroute enp0s31f6
           valid_lft forever preferred_lft forever
        inet6 fe80::329c:23ff:fe74:e0e1/64 scope link 
           valid_lft forever preferred_lft forever
    3: enp4s0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc fq_codel state DOWN group default qlen 1000
        link/ether 68:05:ca:46:4c:39 brd ff:ff:ff:ff:ff:ff
    4: br0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN group default qlen 1000
        link/ether 00:00:00:00:00:00 brd ff:ff:ff:ff:ff:ff
        inet 192.168.1.88/24 brd 192.168.106.255 scope global noprefixroute br0
           valid_lft forever preferred_lft forever
        inet6 fe80::41b8:d2cf:8054:e2c4/64 scope link noprefixroute 
           valid_lft forever preferred_lft forever
    Somehow I would think that a device would be needed on the enp031f6-bridge-slave
    and also I would think that the IP address should not be on both the en0s31f6 interface and the br0 interface.

    What am I missing !?!?

    I've also tried setup this up via the nm-connection-editor with no luck....

  2. #2
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    Re: Help with setting up bridging

    Dear Arnar75,

    Tried to follow your commands.
    On my system, nmcli con up br0 answers:
    Code:
    Connection successfully activated (master waiting for slaves) (D-Bus active path: /org/freedesktop/NetworkManager/ActiveConnection/8)
    Master waiting for slaves ??? The underlying brctl shows:

    Code:
    /sbin/brctl  show
    bridge name	bridge id		STP enabled	interfaces
    br0		8000.000000000000	yes
    The bridge has no slave yet....

    Code:
    nmcli con up enp2s0-bridge-slave
    adds the slave to the master and brings up the connection.


    Another question: where is the broadcast address 192.168.106.255 coming from? It does not fit the network address. But I do not think this is a problem.

    Good luck
    Last edited by hmmsjan; 20th July 2019 at 04:40 PM.
    H.Janssen
    Alkmaar
    The Netherlands

  3. #3
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    Re: Help with setting up bridging

    Its best to configure the bridge inside KVM itself. Also most tutorials, including redhats official, instruct you to turn off NetworkManager. Youll need to delete the default network in virt-manager, and then add a network interface, here you can select bridge and instruct it to copy your ethernets config. Upon createing a VM you wont need to do much for the network just give it an ip on your net with the right gateway (if youre doing a visual install), or edit the network-scripts/FILE as needed.

    this tutorial got me up and running on Centos 7 (should be the same just use dnf instead of yum), if you run into anything were here to help

    http://www.tuxfixer.com/install-and-...ork-interface/

  4. #4
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    Re: Help with setting up bridging

    Gave up on using NetworkManager for this, turned it off and used good old network.
    Seems strange how difficult it is getting bridging to work with NetworkManager.

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