Creating a Bridge Group in Ubuntu ready for GNS3








Commands to set up a bridge group

1. Sets up a tap interface, a tap interface is just a virtual interface inside the systsem.

sudo tunctl -u username -t tap0

-t is the interface name
-u is the unsername

** After entering in the above command a message appears: Set ‘tap0’ persistent and owned by uid 1000
i thought this was an error message the first time i saw it, its not. Its a confirmation from the previous command, you can test to see if the interface was created by issuing:

ifconfig -a 

-a Shows all interfaces even if they are not up.

** You may find tunctl is not installed, if this is the case you need to run the following

sudo apt-get install uml-utilities

2. remove any ip addresses assigned to the interfaces and set them to promiscuous mode (Be careful if you are using eth0 to access your Ubuntu Machine you will disconnect yourself)

sudo ifconfig tap0 promisc up
sudo ifconfig eth0 promisc up

3. Use the bridge control command to setup a new interface

sudo brctl addbr br0

4. Then add our tap0 & eth0 to the bridge interface

sudo brctl addif br0 tap0
sudo brctl addif br0 eth0

5. Bring the bridge interface up and assign it an ip address

sudo ifconfig br0 up
sudo ifconfig br0 (ip address)


sudo btctl show



Your tap0 & eth0 will not have an ip address


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