Thanks janjust for your reply.
I have some questions to your comment to fully understand the problem before I can change the setup.
My OpenVPN server should have the tun0 IP 10.8.0.1
The example client has the tun0 IP 10.8.0.5. To always assign this internal IP to that client, I have created the ccd with the following content on the OpenVPN "Master":
# cat rs05_client
ifconfig-push 10.8.0.5 10.8.0.1
# cat rs06_client
ifconfig-push 10.8.0.6 10.8.0.1
After reading the manual again I get doubts if this correct. My intention is to give the IP 10.8.0.5 to the rs05_client and then specify the internal IP address 10.8.0.1 for the server.
Do I need to change this to the following line for rs05_client:
ifconfig-push 10.8.0.5 10.8.0.6
and for instance to the following line for rs06_client:
ifconfig-push 10.8.0.9 10.8.0.10
Can I then still connect to the master from all clients using 10.8.0.1?
