dev tun
port 1194
proto udp
ca /etc/openvpn/ca.crt
cert /etc/openvpn/server.crt
key /etc/openvpn/server.key
dh /etc/openvpn/dh1024.pem
persist-key
persist-tun
server 10.8.0.0 255.255.255.0
keepalive 10 30
client-to-client
comp-lzo
ifconfig-pool-persist ipp.txt
status /etc/openvpn/openvpn-status.log
verb 3
push "redirect-gateway"

and the openvpn client config is below:

dev tun
client
proto udp
persist-tun
persist-key
resolv-retry infinite
mute-replay-warnings
remote REMOTE.HOST 1194
ca /etc/openvpn/ca.crt
cert /etc/openvpn/client1.crt
key /etc/openvpn/client1.key
comp-lzo
verb 3

The problem:
Using the above config files I continuously got errors like this on the server syslog:

May 1 00:00:00 hostname ovpn-openvpn[22563]: client1/X.Y.Z.W:1194 MULTI: bad source address from client [10.10.1.11], packet dropped

where X.Y.Z.W is my public IP and 10.10.1.11 is the Lan IP of the machine that makes the connection to the openvpn server.

The solution:
finally, here’s the solution for all that problematic configuration:

open your .conf file and edit it! Please add two lines on the bottom below:

dev tun
port 1194
proto udp
ca /etc/openvpn/ca.crt
cert /etc/openvpn/server.crt
key /etc/openvpn/server.key
dh /etc/openvpn/dh1024.pem
persist-key
persist-tun
server 10.8.0.0 255.255.255.0
keepalive 10 30
client-to-client
comp-lzo
ifconfig-pool-persist ipp.txt
status /etc/openvpn/openvpn-status.log
verb 3
push "redirect-gateway"
client-config-dir ccd
route 10.10.1.0 255.255.255.0

once again, remember to add the two lines:

client-config-dir ccd
route 10.10.1.0 255.255.255.0

Then I created the /etc/openvpn/ccd/ dir and put inside a file named client1 with the following contents:

# cat /etc/openvpn/ccd/client1
iroute 10.10.1.0 255.255.255.0

Client configuration stays the same.

All should be fine now and in your server logs you will now see entries like this:

May 1 00:00:00 hostname ovpn-openvpn[27096]: client1/X.Y.Z.W:1194 MULTI: Learn: 10.10.1.11 -> client1/X.Y.Z.W:1194

Remember to load you NAT again!
credit to VOID