In this article I will share step by step guide to configure bridged network in virt-manager (Virtual Machine Manager).

How to configure bridged network in virt-manager (CentOS / RHEL 7)

 

Virtual Machine Manager provides a graphical tool for administering virtual machines for KVM, Xen, and LXC. Start, stop, add or remove virtual devices, connect to a graphical or serial console. You can also see resource usage statistics for existing VMs on local or remote machines. Uses libvirt as the backend management API.

 

What is Bridged Networking?

Bridged networking (also known as network bridging or virtual network switching) will place virtual machine network interfaces on the same network as the physical interface. Bridges require minimal configuration and make a virtual machine appear on an existing network, which reduces management overhead and network complexity. As bridges contain few components and configuration variables, they provide a transparent setup which is straightforward to understand and troubleshoot, if required.

 

Steps to configure bridged network in virt-manager

To configure bridged network in virt-manager for your virtual machine you must have a network bridge active on your host machine so make sure your host have an active working bridge network interface configured on your host machine.

Next install virt-manager on your host machine

Create a new virtual machine by adding all the resources like CPU, Storage, Memory etc.

Next Add NIC card (if not already added) as shown below by clicking on Add Hardware

configure bridged network in virt-manager

 

Look out for the bridge interface from the drop down menu. If the bridge available on your host is shown then you can directly select that bridge but if it is not visible in the drop down menu then select Specify shared device name as shown in the image.

configure bridged network in virt-manager

 

Lastly provide the bridge name from your host machine as shown in the image. The virt-manager will try to connect to the provided bridge interface once you apply the changes.

configure bridged network in virt-manager

 

Now I already have a bridge network interface nm-bridge1, on my host machine

nm-bridge1: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 10.43.138.12  netmask 255.255.255.255  broadcast 10.43.138.12
        inet6 fe80::9edc:71ff:fe77:ef59  prefixlen 64  scopeid 0x20
        ether 9c:dc:71:77:ef:59  txqueuelen 1000  (Ethernet)
        RX packets 46  bytes 2324 (2.2 KiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 37  bytes 5336 (5.2 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

So I will use this interface to configure bridged network in virt-manager.

Click on Apply and power on the VM.

IMPORTANT NOTE:
Ensure that the virtual machine is in powered off state before applying the changes.

Once your virtual machine is UP you can continue with the network configuration using the same network subnet as your physical host’s bridge interface or if you have a DHCP server then you can leave the default configuration and the interface should be able to get the IP address automatically.

Now my vm is also running on the same subnet as the bridge interface from the host Linux node.

# ifconfig
ens3: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 10.43.138.27  netmask 255.255.255.224  broadcast 10.43.138.31
        inet6 fe80::5054:ff:fea2:5a8  prefixlen 64  scopeid 0x20
        ether 52:54:00:7f:7b:ef  txqueuelen 1000  (Ethernet)
        RX packets 132006  bytes 71553811 (68.2 MiB)
        RX errors 0  dropped 248  overruns 0  frame 0
        TX packets 25193  bytes 13135239 (12.5 MiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

 

I hope this article to configure bridged network in virt-manager was useful. Let me know your suggestions and feedback using the comment section.

 

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