How to add network bridge with nmcli (NetworkManager) on Linux ====== I am using Debian Linux 9 "stretch" on the desktop. I would like to create network bridge with NetworkManager. But, I am unable to find the option to add br0. How can I create or add network bridge with nmcli for NetworkManager on Linux? A bridge is nothing but a device which joins two local networks into one network. It works at the data link layer, i.e., layer 2 of the OSI model. Network bridge often used with virtualization and other software. Disabling NetworkManager for a simple bridge especially on Linux Laptop/desktop doesn't make any sense. The nmcli tool can create Persistent bridge configuration without editing any files. **This page shows how to create a bridge interface using the Network Manager command line tool called nmcli**. ### How to create/add network bridge with nmcli The procedure to add a bridge interface on Linux is as follows when you want to use Network Manager: 1. Open the Terminal app 2. Get info about the current connection: ``` nmcli con show ``` 3. Add a new bridge: ``` nmcli con add type bridge ifname br0 ``` 4. Create a slave interface: ``` nmcli con add type bridge-slave ifname eno1 master br0 ``` 5. Turn on br0: ``` nmcli con up br0 ``` Let us see how to create a bridge, named br0 in details. ### Get current network config You can view connection from the Network Manager GUI in settings: [![Getting Network Info on Linux][1]][1] Another option is to type the following command: ``` $ nmcli con show $ nmcli connection show --active ``` [![View the connections with nmcli][2]][2] I have a "Wired connection 1" which uses the eno1 Ethernet interface. My system has a VPN interface too. I am going to setup a bridge interface named br0 and add, (or enslave) an interface to eno1. ### How to create a bridge, named br0 ``` $ sudo nmcli con add ifname br0 type bridge con-name br0 $ sudo nmcli con add type bridge-slave ifname eno1 master br0 $ nmcli connection show ``` [![Create bridge interface using nmcli on Linux][3]][3] You can disable STP too: ``` $ sudo nmcli con modify br0 bridge.stp no $ nmcli con show $ nmcli -f bridge con show br0 ``` The last command shows the bridge settings including disabled STP: ``` bridge.mac-address: -- bridge.stp: no bridge.priority: 32768 bridge.forward-delay: 15 bridge.hello-time: 2 bridge.max-age: 20 bridge.ageing-time: 300 bridge.multicast-snooping: yes ``` ### How to turn on bridge interface You must turn off "Wired connection 1" and turn on br0: ``` $ sudo nmcli con down "Wired connection 1" $ sudo nmcli con up br0 $ nmcli con show ``` Use [ip command][4] to view the IP settings: ``` $ ip a s $ ip a s br0 ``` [![Build a network bridge with nmcli on Linux][5]][5] ### Optional: How to use br0 with KVM Now you can connect VMs (virtual machine) created with KVM/VirtualBox/VMware workstation to a network directly without using NAT. Create a file named br0.xml for KVM using vi command or [cat command][6]: `$ cat /tmp/br0.xml` Append the following code: ``` br0 ``` Run virsh command as follows: ``` # virsh net-define /tmp/br0.xml # virsh net-start br0 # virsh net-autostart br0 # virsh net-list --all ``` Sample outputs: ``` Name State Autostart Persistent ---------------------------------------------------------- br0 active yes yes default inactive no yes ``` For more info read the following man page: ``` $ man ip $ man nmcli ``` ### about the author The author is the creator of nixCraft and a seasoned sysadmin and a trainer for the Linux operating system/Unix shell scripting. He has worked with global clients and in various industries, including IT, education, defense and space research, and the nonprofit sector. Follow him on [Twitter][7], [Facebook][8], [Google+][9]. -------------------------------------------------------------------------------- via: https://www.cyberciti.biz/faq/how-to-add-network-bridge-with-nmcli-networkmanager-on-linux/ 作者：[Vivek Gite][a] 译者：[译者ID](https://github.com/译者ID) 校对：[校对者ID](https://github.com/校对者ID) 本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 [a]:https://www.cyberciti.biz [1]:https://www.cyberciti.biz/media/new/faq/2018/01/Getting-Network-Info-on-Linux.jpg [2]:https://www.cyberciti.biz/media/new/faq/2018/01/View-the-connections-with-nmcli.jpg [3]:https://www.cyberciti.biz/media/new/faq/2018/01/Create-bridge-interface-using-nmcli-on-Linux.jpg [4]:https://www.cyberciti.biz/faq/linux-ip-command-examples-usage-syntax/ (See Linux/Unix ip command examples for more info) [5]:https://www.cyberciti.biz/media/new/faq/2018/01/Build-a-network-bridge-with-nmcli-on-Linux.jpg [6]:https://www.cyberciti.biz/faq/linux-unix-appleosx-bsd-cat-command-examples/ (See Linux/Unix cat command examples for more info) [7]:https://twitter.com/nixcraft [8]:https://facebook.com/nixcraft [9]:https://plus.google.com/+CybercitiBiz