Situation: You have a computer which you want to connect to your already existing network infrastructure.
Problem: You don’t have any switch or hub available only a network card and an already connected computer.
Solution: Use bridging. Its just two clicks away… ok, not really – I don’t like clicking over ssh ;-)
So what I’ll tell you now is what I’ve learned from: http://www.barmasse.org/linux/praxishilfe/ubuntu/virtualbox.html and http://ubuntuforums.org/showthread.php?t=132515 (post from user „woedend“).
Open the file /etc/network/interfaces as root and add the lines:
iface br0 inet dhcp
bridge_ports eth0 eth1
Then install the package bridge-utils and type as root:
You’re dhcp server must be configured to give the br0 interface an IP address. After that, you can do everything with your external connected computer as if it where connected directly.