A Virtual Private Network (VPN) creates an encrypted tunnel over public networks, enabling secure communication between endpoints. Remote workers use VPN to connect securely to corporate resources over the internet. Organizations use site-to-site VPNs to link office locations over public infrastructure as if they were on the same private network.
VPN protocols include IPsec (network layer, often used for site-to-site), SSL/TLS VPN (application layer, common for remote access), and WireGuard (modern, lightweight protocol). Each offers different tradeoffs in security, performance, and ease of deployment.
CISSP Relevance
Domain 4 (Communication and Network Security) covers VPN architectures, protocols, and implementation. Understand tunnel versus transport mode IPsec, split versus full tunneling, and authentication methods. Know how VPN protects confidentiality and integrity of data in transit across untrusted networks.
NIST covers VPN implementation in SP 800-77 Guide to IPsec VPNs.
Related terms: Encryption, Zero Trust