VPNs & Tunnelling

VPNs & Tunnelling

VPNs & Tunnelling


It enables host to access the private network of company via public network or Internet via secure connection.

There are two types of VPN connection.

  • SSL VPNs


In SSL VPN, the upper layer protocol and Transport layer protocols is replaced with another delivery protocols SSL/TLS.

The TLS (Transport Layer Security) and other protocols like Secure Socket Layer are cryptographic protocols based on X.509 digital certificates. It is like client – server process and below is the step of operation.

  • A host starts website requiring SSL Connection.
  • Server will send SSL certificates including server public key
  • Clients verify the certificates and if valid creates the symmetric key which is encrypted with server public key and send back to server.
  • Server decrypts the symmetric session key using private key and send back acknowledgement.
  • All subsequent data is now encrypted with session key.

There are two modes of SSL VPN configuration.

  • Web-only mode
  • Tunnel Mode.

SSL VPN with Web-only Mode:

In web-only mode, user creates the VPN connection via web browser which has built-in SSL encryption and supported Java runtime. Before SSL VPN is created, User must be authorised.

As soon as SSL VPN session is established with fortinet unit, a web portal will be available which list all the supported services like HTTP, HTTPS, and TELNET, SSH etc. just like below screen shot.

SSL VPN with Tunnel Mode:

In this mode VPN tunnel will be created by logging in to Web SSL VPN Portal. In this mode following are the steps.

  • Fortinet unites authenticates host or client via Radius or AD services.
  • The Browser redirects it to portal page
  • A verification of installed VPN client occurs and plugin will be installed if needed.
  • Clients receives VPN address from pool and SSL VPN tunnel is established.


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