VPN types:
Site-to-site (connects offices, always-on, IPSec),
Remote access (individual users, VPN client, SSL or IPSec),
Clientless SSL VPN (browser-based, no client required, portal access).
SSL VPN = modern, works through firewalls (port 443). IPSec VPN = network layer, requires client and UDP 500/4500. Always-on VPN ensures corporate policy applies even off-network. ZTNA is replacing traditional VPN — application-level access instead of network-level.