TUNNEL

TUNNEL

A tunnel is a network communication that integrates another (we then speak of a protocol that "encapsulates" another). This technique is widely used to make networks or machines communicate that otherwise could not speak to each other directly. But for the small world of cybersecurity, we mainly speak of an encrypted tunnel: it is then a question of transmitting information in clear (therefore unprotected) within an end-to-end encrypted communication. A VPN (virtual private network) is such a device. Once an encrypted tunnel is established, all the protocols that use it (http for web browsing, IMAP and SMTP for email, etc.) are routed to the exit point while being invisible to anyone who would be able to intercept the traffic along the way.

For a hacker too, the phrase "seeing the end of the tunnel" is a relief: it means that he has managed to gain a foothold on the remote system.