ip_forward (EN)

Definition

IP-Forwarding is a kernel feature that enables a system to forward IP packets between different network interfaces. In VPN contexts, IP-Forwarding is essential for the VPN server to forward traffic between the VPN tunnel and the local network. Without activated IP-Forwarding, VPN clients can establish a connection to the server but cannot access resources in the internal network. Activation is typically done with the command 'sysctl net.ipv4.ip_forward=1' and should be permanently anchored in the system configuration.

Data Flow

flowchart LR   A[VPN-Client] -->|VPN-Tunnel| B[VPN-Server]   B -->|IP-Forwarding| C[Internal Network]   C -->|Response| B   B -->|VPN-Tunnel| A 

In Context

• Typically used together with NAT, firewalls, and routing tables
• Related to: Routing, VPN, Network bridge, sysctl
• Example use cases: Gateway servers, VPN servers, Docker container networks