I need to do mutual authentication between two httpd servers. The first server will receive connection from outside and proxy pass them to another httpd. So I activated, in the first server's virtual host the SSLProxyCACertificateFile parameter, but when I reloaded, httpd crashed. After some investigations I saw the kernel semaphore amount increasing to the maximum (2048) until the apache crash. Is it a bug or a problem in my configuration.