Summary VPN - Virtual Private Network

VPN – Virtual Private Network

Tunneling - network communications process that protects the contents of
the protocol packets by encapsulating them in packets of another protocol -
encapsulation creates a logical illusion of communications tunnel over an
untrusted network

How VPN's work

Establish over any other network - LAN cable connection or LAN wireless or
remote dial up or WAN link

Can connect 2 individual systems or entire networks

Remote access servers or firewalls at the border act as starting points

Common VPN protocols

 PPTP - operated at the data link layer or layer 2

o Not encrypted often replaced by L2TP

 L2F - operated at the data link layer or layer 2

 L2TP - operated at the data link layer or layer 2

 IPSec - requires Internet networks - most common - includes security
elements for IPv6

o AH - Authentication Header for authentication, integrity and
nonrepudiation

o ESP - Encapsulating Security Payload - encryption to protect the
confidentiality of transmitted data - performs limited
authentication - operates at the Session layer or Layer 3

o Transport or tunnel mode

 PPTP- requires Internet networks

VPN Native Native Protocols Dial-up # of
Protocol Authentication Data Supported Links Simultaneous
Protection Encryption Supported Connections

PPTP Yes No PPP Yes Single point
to point



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