1.8. Configuring TLS client certificate authentication

Procedure

1. Edit the /etc/httpd/conf/httpd.conf file and add the following settings to the <VirtualHost> directive for which you want to configure client authentication:

   <Directory "/var/www/html/Example/">
     SSLVerifyClient require
   </Directory>

   The SSLVerifyClient require setting defines that the server must successfully validate the client certificate before the client can access the content in the /var/www/html/Example/ directory.

2. Restart the httpd service:

   # systemctl restart httpd

Verification

1. Use the curl utility to access the https://example.com/Example/ URL without client authentication:

   $ curl https://example.com/Example/
   curl: (56) OpenSSL SSL_read: error:1409445C:SSL routines:ssl3_read_bytes:tlsv13 alert certificate required, errno 0

   The error indicates that the web server requires a client certificate authentication.

2. Pass the client private key and certificate, as well as the CA certificate to curl to access the same URL with client authentication:

   $ curl --cacert ca.crt --key client.key --cert client.crt https://example.com/Example/

   If the request succeeds, curl displays the index.html file stored in the /var/www/html/Example/ directory.