A Virtual Private Network (VPN) is a mechanism that is used to establish a secure connection over an insecure network, such as the Internet. Various technologies and methodologies can be used to create such an entity which ensures that traffic exchanged between its endpoints remains private and separate from any other traffic that may be traversing the same network.

VPNs provide the following features:

  • Confidentiality: preventing anyone from reading your data. This is implemented with encryption.
  • Authentication: verifying that the router/firewall or remote user that is sending VPN traffic is a legitimate device or router.
  • Integrity: verifying that the VPN packet wasn’t changed somehow during transit.
  • Anti-replay: preventing someone from capturing traffic and resending it, trying to appear as a legitimate device/user.

VPNs are used in a variety of contexts including:

VPNs can be established as site-to-site, where remote LANs are interconnected over a WAN, or can be established as client-to-site, where individual devices connect securely to a remote network.



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