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How To Setup Bridge (br0) Network on Ubuntu Linux 14.04 and 16.04 LTS
am a new Ubuntu Linux 16.04 LTS user. How do I setup a network bridge on the host server powered by Ubuntu 14.04 LTS or 16.04 LTS operating system?
A Bridged networking is nothing but a simple technique to connect to the outside network through the physical interface. It is useful for LXC/KVM/Xen/Containers virtualization and other virtual interfaces. The virtual interfaces appear as regular hosts to the rest of the network. In this tutorial I will explain how to configure a Linux bridge with bridge-utils (brctl) command line utility on Ubuntu server.
Our sample bridged networking
Fig.01: Sample Ubuntu Bridged Networking Setup For Kvm/Xen/LXC Containers (br0)
In this example eth0 and eth1 is the physical network interface. eth0 connected to the LAN and eth1 is attached to the upstream ISP router/Internet.
Install bridge-utils
Type the following [apt-get command][1] to install the bridge-utils:
$ sudo apt-get install bridge-utils
OR
$ sudo apt install bridge-utils
```
Sample outputs:
>Fig.02: Ubuntu Linux install bridge-utils package
### Creating a network bridge on the Ubuntu server
Edit `/etc/network/interfaces` using a text editor such as nano or vi, enter:
```
$ sudo cp /etc/network/interfaces /etc/network/interfaces.bakup-1-july-2016
$ sudo vi /etc/network/interfaces
```
Let us setup eth1 and map it to br1, enter (delete or comment out all eth1 entries):
```
# br1 setup with static wan IPv4 with ISP router as gateway
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
```
To setup eth0 and map it to br0, enter (delete or comment out all eth1 entries):
```
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 config options:
```
auto br0
iface br0 inet dhcp
bridge_ports eth0
bridge_stp off
bridge_fd 0
bridge_maxwait 0
```
Save and close the file.
### Restart the server or networking service
You need to reboot the server or type the following command to restart the networking service (this may not work on SSH based session):
```
$ sudo systemctl restart networking
```
If you are using Ubuntu 14.04 LTS or older not systemd based system, enter:
```
$ sudo /etc/init.d/restart networking
```
### Verify connectivity
Use the ping/ip commands to verify that both LAN and WAN interfaces are reachable:
```
# See br0 and br1
ip a show
# See routing info
ip r
# ping public site
ping -c 2 cyberciti.biz
# ping lan server
ping -c 2 10.0.80.12
```
Sample outputs:
>Fig.03: Verify Bridging Ethernet Connections
Now, you can configure XEN/KVM/LXC containers to use br0 and br1 to reach directly to the internet or private lan. No need to setup special routing or iptables SNAT rules.
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作者：[VIVEK GITE][a]
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[1]: http://www.cyberciti.biz/tips/linux-debian-package-management-cheat-sheet.html