/var/tmp/mongo/contrib/php-ssl.h:33:25: error: openssl/evp.h: No such file or directory

Compilation error : mongo compilation error :
/var/tmp/mongo/contrib/php-ssl.h:33:25: error: openssl/evp.h: No such file or directory

Solution :

You need to install package openssl-devel

Run following command on Centos/Fedora/RHEL

yum install openssl-devel

Now try to compile your package again, you will not get this error.