Librecmc can operate as an OpenVPN server. OpenVPN technology connects two networks via an encrypted tunnel. With proper server, network, and client configuration, OpenVPN allows a client outside of your LAN to see the LAN as though it were physically connected to the LAN.
OpenVPN can run in layer 2 or layer 3 mode. In layer 3 mode, the remote client sees your LAN as though it is on the other side of an IP router. In layer 2 mode, the remote client sees your LAN as though they are both on the same Data Link segment (e.g., the same Ethernet link). Layer 3 mode is easier to set up, but layer 2 mode is sometimes desired to give clients a more direct exposure to services on the LAN.
This information is provided for educational purposes only and is not meant to be a guide to best network security practices. Readers are advised to study all relevant OpenVPN and network security documentation.
In LuCi, select
Interfaces and then
Add New Interface.
Name of the new interfaceto
myvpnor anything else you would like.
Protocol of the new interfaceto unmanaged.
Cover the following interfaceto
Custom Interface: vpn0.
firewall-zonefor the interface is set to
lan, but I don't think that really matters in this case.
In my working configuration, I added tap0 into the LAN bridge interface, and deleted the WAN interface. However, my vpn server is a separate unit on my network, intended to operate in "bridge mode", where if you server is your gateway router, a different configuration might be necessary.
cd /etc/easy-rsa source vars clean-all build-ca build-dh build-key-server myvpn openvpn --genkey --secret /etc/easy-rsa/keys/ta.key mkdir -m 700 /etc/openvpn/keys mv ca.crt myvpn.crt myvpn.key dh2018.pem /etc/openvpn/keys
N.B.: Using easy-rsa is a straightforward approach, but it may be possible to produce more secure certificates using openssl directly.
server bridge option: The first two parameters are the ip
and netmask of the gateway on the bridged subnet. The next two
parameters indicate the pool-start-IP and pool-end-IP, which is the
part of your IP address pool that you have reserved just for VPN
clients. You must to make sure that the DHCP server for your LAN is
not leasing out those IP addresses to local (non-vpn) clients.
config openvpn 'myvpn' option enabled '1' option dev 'tap0' option port '1194' option proto 'udp' option keepalive '10 120' option persist_key '1' option persist_tun '1' option user 'nobody' option group 'nogroup' option ca '/etc/openvpn/keys/ca.crt' option cert '/etc/openvpn/keys/myvpn.crt' option key '/etc/openvpn/keys/myvpn.key' option dh '/etc/openvpn/keys/dh2048.pem' option tls_server '1' option tls_auth '/etc/openvpn/keys/ta.key 0' option server_bridge '10.0.0.1 255.255.255.0 10.0.0.201 10.0.0.220' option client_to_client '1' list push 'persist-key' list push 'persist-tun' list push 'redirect-gateway def1' list push 'route 10.0.0.0 255.255.255.0' list push 'dhcp-option DNS 10.0.0.1' option mute '15' option verb '3'