How to set up a network bridge (br0) on Ubuntu Linux 14.04 and 16.04 LTS

This post will discuss how to set up a network bridge on a server running Ubuntu 14.04 LTS or 16.04 LTS.

A network bridge is nothing more than a simple technical method of connecting to an external network through a physical interface. This is useful when using LXC / KVM / Xen / Containers virtualization and other virtual interfaces. This tutorial will explain how you can configure a Linux bridge using bridge-utils (brctl) to a server with Ubuntu.

Network bridge example:
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In this example, eth0 and eth1 are the physical network interface. eth0 is connected to the LAN and eth1 is connected directly to the provider equipment.

Install bridge-utils

Enter the apt-get command to install bridge-utils:

$ sudo apt-get install bridge-utils 

or

 $ sudo apt install bridge-utils 

Result:

Create a network bridge on a server with Ubuntu

Edit / etc / network / interfaces using a text editor such as nano, vi, or any other editor you like, and enter:

 $ sudo cp /etc/network/interfaces /etc/network/interfaces.bakup-1-july-2016 $ sudo vi /etc/network/interfaces 

Next, install eth1 and mark it as br1, enter:

 # br1   IPv4 ,    -   auto br1 iface br1 inet static address 208.43.222.51 network 255.255.255.248 netmask 255.255.255.0 broadcast 208.43.222.55 gateway 208.43.222.49 bridge_ports eth1 bridge_stp off bridge_fd 0 bridge_maxwait 0 

Set eth0 and mark it as br0, enter:

 auto br0 iface br0 inet static address 10.18.44.26 netmask 255.255.255.192 broadcast 10.18.44.63 dns-nameservers 10.0.80.11 10.0.80.12 # set static route for LAN post-up route add -net 10.0.0.0 netmask 255.0.0.0 gw 10.18.44.1 post-up route add -net 161.26.0.0 netmask 255.255.0.0 gw 10.18.44.1 bridge_ports eth0 bridge_stp off bridge_fd 0 bridge_maxwait 0 

A note about br0 and DHCP

DHCP settings:

 auto br0 iface br0 inet dhcp bridge_ports eth0 bridge_stp off bridge_fd 0 bridge_maxwait 0 

Save and close the file.

Restart server or network service

Now you need to restart the server or enter a command to restart the network service:

 $ sudo systemctl restart networking 

If you are using Ubuntu 14.04 LTS or an older version of the distribution, enter:

 $ sudo /etc/init.d/restart networking 

Command connectivity check

Use the ping / ip command to make sure the LAN and WAN interfaces are available:

 #   br0  br1 ip a show #   ip r #     ping -c 2 8.8.8.8 #     ping -c 2 10.0.80.12 

Result:



You can now configure XEN / KVM / LXC containers to use br0 and br1 and access the Internet or an internal LAN directly. Thus, there is no need to install a special routing table or create iptables, SNAT rules.

Source: www.cyberciti.biz/faq/how-to-create-bridge-interface-ubuntu-linux