# How do I enable IP forwarding?

If you are using a routing-based VPN (**dev tun**) and you would like to configure your OpenVPN server or client to act as a VPN gateway for a LAN, you should enable IP forwarding. Also make sure that your network interface is in promiscuous mode.

On Windows, see [this TechNet article](https://technet.microsoft.com/en-us/library/cc962461.aspx).

On Linux, use the command:
```
echo 1 > /proc/sys/net/ipv4/ip_forward
```

On OS X:
```
sudo sysctl -w net.inet.ip.forwarding=1
```