I recieved this e-mail from my webserver:

################# SSL Certificate Warning ################  Certificate for hostname 'yourservername.com', in file (or by nickname):     /etc/pki/tls/certs/localhost.crt  The certificate needs to be renewed; this can be done  using the 'genkey' program.  Browsers will not be able to correctly connect to this  web site using SSL until the certificate is renewed. ##########################################################                                  Generated by certwatch(1)

So I had to renew this certificate on my CentOS Server.

All you have to do is to enter this command:

openssl req -new -days 3650 -x509 -nodes -newkey rsa:2048 -out /etc/pki/tls/certs/localhost.crt -keyout /etc/pki/tls/private/localhost.key

And then restart the web server, in my case it’s apache:

apachectl restart

After this, you can check with your webbrowser if the new certificate is active. Check the new expire date. With mozilla firefox it’s “Extra” -> “Site information” -> “Security” -> “Show certificate”.