Telecommuters, regional salespeople, satellite and branch offices, and business partners are just a few groups who may need remote access to a corporation's resources. Each group needs access, but the requirements are very different.
The communications tunnel allows communications between two computers over public networks securely so that other computers on those networks cannot access the communications between the two machines.
Tunneling involves encrypting all communications between the two computers so that even if another computer were to receive the communications, it would not be able to decipher the contents of the actual message between the machines.
Requiring authentication from users before allowing access, so that only authorized parties can establish tunnels.
Encrypting all data transmitted to and from the user by implementing the actual tunnel using SSL.
The process of establishing an SSL tunnel requires the exchange of different configuration information between the computers on either end of the connection — including the technical details related to communication and encryption protocols and key exchange.
Historically, VPN tunneling was typically performed at the Network Layer or lower. SSL VPNs work differently — establishing connectivity using SSL, which functions at Levels 4–5, encapsulating information at Levels 6–7, and communicating at the highest levels in the OSI model.
Network Layer or lower
Levels 4–5 (Session)
Levels 6–7 (Presentation/Application)
