Configuring a dynamic IP address bridge

If your network configuration is controlled by a DHCP server, perform this task to configure a dynamic IP address bridge.

To display the available network interfaces, enter cat /etc/network/interfaces.

user @ubuntu:~$ cat /etc/network/interfaces

# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).

source /etc/network/interfaces.d/*

# The loopback network interface
auto lo
iface lo inet loopback

# The primary network interface
auto ens3
iface ens3 inet dhcp

Enter ifconfig -a to verify that the Ethernet interface is up.
```
user@ubuntu:~$ ifconfig -a
```
Enter the ping command—specifying a known URL—to verify that you have internet connectivity.
```
user@ubuntu:~$ ping example.com
```

Install bridge-utils, using the following commands:

user@ubuntu:~$ sudo apt-get update
user@ubuntu:~$ sudo apt-get install bridge-utils

Enter sudo vi /etc/network/interface to modify the interfaces file.
```
user@ubuntu:~$ sudo vi /etc/network/interface
```

Define the br0 bridge and enslave the primary network interface (ens in the following example) under br0.

# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).

source /etc/network/interfaces.d/*

# The loopback network interface
auto lo
iface lo inet loopback

# The primary network interface
# We commented out the following two lines:
#auto ens3
#iface ens3 inet dhcp

# We added the following definition of br0:
auto br0
iface br0 inet dhcp
        bridge_ports ens3
        bridge_stp off
        bridge_fd 0
        bridge_maxwait 0

Save and close the file.
Reboot the server.
```
user@ubuntu:~$ sudo reboot
```

After logging back in, enter ifconfig -a to verify that the IP address is now assigned to br0.

user@ubuntu:~$ ifconfig -a
br0       Link encap:Ethernet  HWaddr 52:55:00:d1:55:01  
          inet addr:10.0.0.110  Bcast:10.0.0.255  Mask:255.255.255.0
          inet6 addr: 2601:644:8780:2e56:e99d:2411:3c93:b7e6/64 Scope:Global
          inet6 addr: 2601:644:8780:2e56:5055:ff:fed1:5501/64 Scope:Global
          inet6 addr: fe80::5055:ff:fed1:5501/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:142 errors:0 dropped:0 overruns:0 frame:0
          TX packets:93 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:18815 (18.8 KB)  TX bytes:13887 (13.8 KB)

ens3      Link encap:Ethernet  HWaddr 52:55:00:d1:55:01  
          inet6 addr: fe80::5055:ff:fed1:5501/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:142 errors:0 dropped:0 overruns:0 frame:0
          TX packets:103 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:20803 (20.8 KB)  TX bytes:14793 (14.7 KB)

lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:65536  Metric:1
          RX packets:80 errors:0 dropped:0 overruns:0 frame:0
          TX packets:80 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1 
          RX bytes:5920 (5.9 KB)  TX bytes:5920 (5.9 KB)