Proxy ARP

In this recipe, we will use the proxy-arp feature of the Linux kernel to make the VPN clients appear as part of the server-side LAN. This eliminates the need to use bridging, which is desirable in most cases.

Getting ready

This recipe uses the PKI files created in the first recipe of this chapter. For this recipe, the server computer was running CentOS 6 Linux and OpenVPN 2.3.9. The client was running Windows 7 64 bit and OpenVPN 2.3.10. For the server, keep the server configuration file, basic-udp-server.conf, from the Server-side routing recipe at hand. For the Windows client, keep the corresponding client configuration file, basic-udp-client.ovpn, from the Using an ifconfig-pool block recipe at hand.

We use the following network layout:

How to do it...

1. Create the server config file by adding the following lines to the basic-udp-server.conf file:

           script-security 2 
           client-connect    /etc/openvpn/cookbook/proxyarp-connect.sh 
           client-disconnect /etc/openvpn/cookbook...