The default installation of virutalmin doesn’t come with additional PHP extensions which some php scripts may need, you have to manually install each php extension compare with easyapache from cPanel which you can install all at once.
Add centOS repo
For CentOS 5
rpm -Uvh http://download.fedoraproject.org/pub/epel/5/i386/epel-release-5-4.noarch.rpm
For CentOS 6
rpm -Uvh http://download.fedoraproject.org/pub/epel/6/i386/epel-release-6-7.noarch.rpm
yum install php-mcrypt
Check php.ini location ( /etc/php.ini is the default virtualmin php.ini location )
php -i | grep php.ini
nano /etc/php.ini
add extension to php.ini
extension =mcrypt.so
Retart Apache Server
/etc/init.d/httpd restart
After adding centOS Repositories, you could install php extension from virtualmin GUI
Webmin > System Software Packages > Choose Package from YUM > Click Browse YUM, type the php extension name in the search box and click find packing matching button, and then click the package name install.
Add php extension to php.ini from virtualmin GUI
Webmin > Others > PHP Configuration > Edit Manually
Don’t forget to restart apache server.
Most popular PHP extension you may need:
Format: extension = [extension name].so
•bcmath •curl •dba •dom •fileinfo •gd •imap •imagick •json •ldap •mailparse •mbstring •mcrypt •mysql •mysqli •ncurses •odbc •pdo •pdo_mysql (requires pdo) •pdo_odbc (requires pdo) •pdo_pgsql (requires pdo) •pdo_sqlite (requires pdo) •pgsql •rrdtool •snmp •soap •tidy •xmlreader •xmlrpc •xmlwriter •xsl •zip