Backtrack 5 VM: Bridged Networking Explained

TL;DR

Bridged networking gives your Backtrack 5 virtual machine (VM) its own IP address on your home network, making it act like a separate computer. This is better than NAT for tasks like penetration testing and sniffing traffic because you can directly interact with other devices on the network without translation issues.

Why Bridged Networking?

Backtrack 5 (and Kali Linux) are often used for cyber security work, including ethical hacking. NAT (Network Address Translation) hides your VM behind your host computer’s IP address. While easy to set up, it creates problems when you need the VM to be directly visible on the network.

Setting Up Bridged Networking

1. Identify Your Host Network Interface: You need to know which network connection your host machine uses to connect to the internet. On Linux:

   ip addr

   Look for an interface like eth0 or wlan0 with an IP address (e.g., 192.168.1.x). On Windows, open Command Prompt and type:

   ipconfig /all

   Find the adapter connected to your network (Ethernet or Wi-Fi) and note its name.

2. VirtualBox Settings: Shut down your Backtrack 5 VM completely. Do not just save the machine state; power it off.
   • Select your VM in VirtualBox Manager.
   • Click ‘Settings’.
   • Go to ‘Network’ tab.
   • Adapter 1: Enable Network Adapter.
   • Attached to: Select ‘Bridged Adapter’.
   • Name: Choose the network interface you identified in step 1 (e.g., eth0, wlan0).
3. Start Your VM: Power on your Backtrack 5 VM.
4. Verify IP Address: Log into your Backtrack 5 VM and check its IP address:

   ifconfig

   The IP address should be in the same range as your host machine’s network, but a different number (e.g., if your host is 192.168.1.10, your VM might be 192.168.1.15).

Why Bridged Networking is Better for Cyber Security

• Direct Access: Your VM has a real IP address on the network, allowing other devices to connect directly to it.
• Penetration Testing: Tools like Metasploit work more reliably when your VM isn’t hidden behind NAT. You can scan and attack targets as if you were a separate computer on the same network.
• Packet Sniffing: Tools like Wireshark can capture all traffic passing through your bridged interface, giving you a complete view of network activity. With NAT, you only see translated traffic.
• No Port Forwarding: You don’t need to configure port forwarding rules on your router, which can be complex and insecure.

Troubleshooting

• Network Conflicts: If the VM doesn’t get an IP address, try restarting the networking service in Backtrack 5:

  sudo /etc/init.d/networking restart

• Firewall Issues: Make sure your host machine’s firewall isn’t blocking traffic to or from the VM.
• Adapter Selection: Double-check that you’ve selected the correct network adapter in VirtualBox settings.