TechFindings

I am posting my working OpenVPN server configuration, and client configuration for Linux, Android and iOS. First a little background.

I have an OpenWRT (14.07) router running OpenVPN server. This router has a public IP address and thanks to dyn.com/dns it can be resolved using a domain name (ROUTER.PUBLIC in all configuration examples below).

My router LAN address is 192.168.8.1, the LAN network is 192.168.8.*, and the OpenVPN network is 192.168.9.* (in this range OpenVPN-clients will be given an address to their vpn/dun-device). I run OpenVPN on TCP 1143.

What I want to achieve is
1) to access local services (like ownCloud and ssh) of computers on the LAN
2) to access internet as if I were at home, when I have an internet access that is somehow restricted

The Server
Essentially, this OpenWRT OpenVPN Setup Guide is very good. Follow it. I am not going to repeat everything, just post my working configurations.

root@breidablick:/etc/config# cat openvpn 

config openvpn 'myvpn'
	option enabled '1'
	option dev 'tun'
	option proto 'tcp'
	option status '/tmp/openvpn.clients'
	option log '/tmp/openvpn.log'
	option verb '3'
	option ca '/etc/openvpn/ca.crt'
	option cert '/etc/openvpn/my-server.crt'
	option key '/etc/openvpn/my-server.key'
	option server '192.168.9.0 255.255.255.0'
	option port '1143'
	option keepalive '10 120'
	option dh '/etc/openvpn/dh2048.pem'
	option push 'redirect-gateway def1'
	option push 'dhcp-option DNS 192.168.8.1'
	option push 'route 192.168.8.0 255.255.255.0'

It is a little unclear if the last three options really work for all clients. I also have:

root@breidablick:/etc/config# cat network 
.
.
.
config interface 'vpn0'
	option ifname 'tun0'
	option proto 'none'

and

root@breidablick:/etc/config# cat firewall 
.
.
.
config zone
	option name 'vpn'
	option input 'ACCEPT'
	option forward 'ACCEPT'
	option output 'ACCEPT'
	list network 'vpn0'
.
.
.
config forwarding
	option src 'lan'
	option dest 'vpn'

config forwarding
	option src 'vpn'
	option dest 'wan'
.
.
.
# may not be needed depending on your lan policys (2 next)
config rule
	option name 'Allow-lan-vpn'
	option src 'lan'
	option dest 'vpn'
	option target ACCEPT
	option family 'ipv4'

config rule
	option name 'Allow-vpn-lan'
	option src 'vpn'
	option dest 'lan'
	option target ACCEPT
	option family 'ipv4'
.
.
.
# may not be needed depending on your wan policy
config rule
	option name 'Allow-OpenVPN-from-Internet'
	option src 'wan'
	option proto 'tcp'
	option dest_port '1143'
	option target 'ACCEPT'
	option family 'ipv4'

iOS client
You need to install OpenVPN client for iOS from the app store. The client configuration is prepared on your computer, and synced with iOS using iTunes (brilliant or braindead?). This is my working configuration:

client
dev tun
ca ca.crt
cert iphone.crt
key iphone.key
remote ROUTER.PUBLIC 1143 tcp-client
route 0.0.0.0 0.0.0.0 vpn_gateway
dhcp-option DNS 192.168.8.1
redirect-gateway def1

This route and redirect-gateway configuration makes all traffic go via VPN. Omit those lines if you want direct internet access.

Android client
For Android, you also need to install the OpenVPN client from the Store. My client is the “OpenVPN for Android” by Arne Schwabe. This client has a GUI that allows you to configure everything (but you need to get the certificate files to your Android device somehow). You can watch the entire Generated Config in the GUI and mine looks like this (omitting GUI and Android-specific stuff, and the certificates):

ifconfig-nowarn
client
verb 4
connect-retry-max 5
connect-retry 5
resolv-retry 60
dev tun
remote ROUTER.PUBLIC 1143 tcp-client
route 0.0.0.0 0.0.0.0 vpn_gateway
dhcp-option DNS 192.168.8.1
remote-cert-tls server
management-query-proxy

Linux client
I also connect linux computers occationally. The configuration is:

client
remote ROUTER.PUBLIC 1194
ca ca.crt
cert linux.crt
key linux.key
dev tun
proto tcp
nobind
auth-nocache
script-security 2
persist-key
persist-tun
user nobody
group nogroup
verb 5
# redirect-gateway local def1
log log.txt

Here the redirect-gateway is commented away, so internet traffic is not going via VPN.

Certificates
The easy-rsa package and instructions in the OpenWRT guide above are excellent. You should have different certificates for different clients. One certificate can only be used for one connection at a time.

Better configuration?
I dont say this is the optimal or best way to configure OpenVPN – but it works for me. You may prefer UDP over TCP, and may reasons for running TCP are perhaps not valid for you. You may want different encryption or data compressions options, different logging options and so on.