openvpn configure notes

openvpn configure notes:

Follow the process on debian wiki: https://wiki.debian.org/OpenVPN
The process is almost OK. Only a few adjustments is required as below:

checking:
$ which openvpn

The default directory after installation is: /etc/openvpn/
All relative path in .conf files points to this path.

Openvpn will start automatically when server reboots.

Openvpn will check each .conf file under /etc/openvpn and use all of them when possible

Be sure to execute the 3 iptables command, in case the response packet couldn't return to VPN server due to improper src address in request packets.

iptables -A FORWARD -i eth0 -o tun0 -m state --state ESTABLISHED,RELATED -j ACCEPT
iptables -A FORWARD -s 10.9.8.0/24 -o eth0 -j ACCEPT
iptables -t nat -A POSTROUTING -s 10.9.8.0/24 -o eth0 -j MASQUERADE

Check the netmask of subnet.

change dev0 to dev in the formal .conf file. Reasons unknown.

Print "y" for any command prompt when execute the following the lines:
# ./build-ca
# ./build-key-server server
./build-dh
./build-key clientname

Change relative paths to absolute paths for the first time. And change back to relative paths when necessary.

Some directives in the .conf file could be changed or removed.

changed directives:
port 1194
proto udp

removed directives:
push "dhcp-option DNS 8.8.8.8"
client-to-client
set CLIENT_CERT 0

Folloing route commands in the client is not necessary:
# ip route add VPNSERVER_IP via LOCALGATEWAY_IP dev eth0  proto static
# ip route change default via 10.9.8.5 dev tun0  proto static   //client tun0 10.9.8.5