certificate management under Debian/Ubuntu

Add

1. Copy your CA to dir /usr/local/share/ca-certificates/
   
2. Update the CA store:
   sudo update-ca-certificates
   

Remove

1. Remove your CA.
   
2. Update the CA store:
   sudo update-ca-certificates --fresh

I could not find Gui interfaces, only this technique

Please note that the certificate filenames have to end in .crt, otherwise the update-ca-certificates script won't pick up on them.

To see the certificates on a server :
openssl s_client -showcerts -connect <myserver>:<ssl_port>