Virtual Static IPv4 address

This is the forum to post your config. Include diagrams, usage graphs, and all the other goodies to show off your network.
Post Reply
DieterH
OpenVpn Newbie
Posts: 1
Joined: Wed Oct 23, 2019 7:35 am

Virtual Static IPv4 address

Post by DieterH » Wed Oct 23, 2019 8:03 am

Good morning,

I run an OpenVPN server (v2.4) to allow project partners access to our data center. For project partner A I set up a CCD file to ensure a virtual static IPv4 address (topology subnet). Everything works fine.

Project partner B has many VPN clients each of which needs a unique virtual static IPv4 address. As the CCD files are based on Common Names (CN), one solution would be to create a unique user, a unique client CRT file and also a unique client KEY file. This approach is basically that one for project partner A.

Having already pointed out that the name of each CCD file is the CN, I tried the following approach:
1. Creating a "universal" client CRT and client KEY file, thus resulting in a "template CRT file". The CN is set to "ProjB".
2. Defining unique tokens serving as CNs; these tokens are "ProjB_client1" and "ProjB_client2".
3. Copying the CRT file (from step 1) and replacing in the copied files the CN entry "ProjB" by "ProjB_client1" and "ProjB_client2" respectively, leaving all other stuff in the copied files untouched.
4. Creating 2 CCD files "ProjB_client1" and "ProjB_client2".
5. Making project partner B install these modified CRT files (Note: Project partner B can successfully establish a connection to OpenVPN server with the original CRT file).
6. When establishing a connection with the modified CRT files (the original client KEY file is still in use and has not been exchanged), the following error messages show up:
Tue Oct 22 12:11:44 2019 OpenSSL: error:0B080074:x509 certificate routines:X509_check_private_key:key values mismatch
Tue Oct 22 12:11:44 2019 Cannot load private key file /home/xxxx/OpenVPN/config/ProjB.key
Tue Oct 22 12:11:44 2019 Error: private key password verification failed
Tue Oct 22 12:11:44 2019 Exiting due to fatal error

There are several questions now:
1. What is basically wrong with my approach described above? (Only CN in client CRT file was replaced)?
2. Is there a better way of assigning virtual static IPv4 addresses for many VPN clients (my test was for 2 VPN clients only, but B has many VPN clients)?

Appreciating your answers.

Best regards
Dieter

Post Reply