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Barracuda SSL VPN

What is an SSL Tunnel and how do I configure one on my Barracuda SSL VPN?

  • Type: Knowledgebase
  • Date changed: 2 years ago
Solution #00003719

This solution applies to Barracuda SSL VPNs, all firmware versions.

Tunneling is a method of transmission over networks based on differing protocols. In tunneling, a packet based on one protocol is wrapped, or encapsulated, in a second packet based on whatever differing protocol is needed in order for it to travel over an intermediary network. In effect, the second wrapper insulates the original packet and creates the illusion of a tunnel through which the wrapped packet travels across the intermediary network. For example, TCP can be wrapped in an SSL Tunnel.

Practically speaking, tunneling is comparable to encapsulating an item (the original packet) in a box (the secondary wrapper) for delivery through the postal system. When a tunnel is activated on your Barracuda SSL VPN, a tunnel is created between the source port on your system and port 443 through the Barracuda SSL VPN, from there the Barracuda SSL VPN connects to the destination port on the target IP address inside the LAN.

An SSL tunnel will simply use the Barracuda SSL VPN Agent to open up a tunnel from a port on the client machine to a port on the destination machine, which will direct traffic from the client through the tunnel to the destination machine. The tunnel can thereby enable direct communication between the client machine and the destination machine, which can then be used by a client-side application. The flexibility and "on-demand" nature of tunnels over the Barracuda SSL VPN make them more desirable and secure than permanently opening ports on an external firewall, or granting a client machine unrestricted network access via a traditional VPN.

To create an SSL Tunnel on your Barracuda SSL VPN, take the following steps:
  1. Login to your Barracuda SSL VPN using your administrator login credentials, and navigate to Resources > SSL Tunnels.
  2. Enter a unique Name. Optionally you may add the tunnel to your favorites, or set it to start automatically on login.
  3. Enter a Source Interface, a Source Port, a Destination Host, and a Destination Port.
  4. Select the appropriate policy or policies to which you will attach the tunnel by selecting the name and clicking on the Add button.
  5. Review the settings, and if everything is correct click Add.
Additional Notes:
For an explanation of tunneling, including information on local and remote forwarding, please refer to the following link:

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