VPN Tunneling
VPN tunneling wraps one protocol inside another, allowing packets to traverse networks that would otherwise block or be unaware of the inner protocol. The original packet becomes the payload of an outer packet. At the far end, the outer headers are stripped and the original packet is delivered - enabling VPNs, data center overlays, and protocol bridging.
Packet Structure
Tunnel Protocols
GRE (Generic Routing Encapsulation) - IP proto 47
IPSec (ESP) - encrypted tunnel, IP proto 50
VXLAN - L2 over L3, UDP port 4789
Event Log