Motivation for VPNs:
Traditional corporate networks used leased lines from a telephone company. The cost of these was dependent on distance and time of usage. Remote users would incur long distance charges by dialing in.
The solution for this, was setting up tunnels through the internet.
Corporations saw an 80% reduction in cost.
A VPN connects the resources and components of one network to another over a public infrastructure, via the use of a dedicated link.
How does a VPN work?
- A VPN establishes tunnels through the internet to send packets.
- What is a tunnel?
→ just a logical stream of packets in which each packet is encapsulated with an additional header as it travels through the public network
→ with the extra header, you can encrypt the content of the packet, authenticate or certify.
→ putting firewalls at either end of the tunnel ensures access control and availabiltiy.
What do we need to set up a VPN tunnel?
A VPN tunneling protocol.
PPTP, L2F, L2TP...
but the most popular is IPSec
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