首先下载，并安装
libmcrypt-2.5.8.tar.gz
下载地址: http://sourceforge.net/project/showfiles.php?group_id=87941&package_id=91774&release_id=487459
mhash-0.9.9.tar.gz
下载地址: http://sourceforge.net/project/showfiles.php?group_id=4286&package_id=4300&release_id=645636
mcrypt-2.6.8.tar.gz
下载地址: http://sourceforge.net/project/showfiles.php?group_id=87941&package_id=91948&release_id=642101
安装流程是一样的，加压后，进入解压包
./configure
make && make install
然后开始安装PHP扩展
进入PHP安装包下的ext文件夹，找到mcrypt
cd /home/local/php5.6.25/ext/mcrypt
phpize
./configure --with-php-config=/usr/local/php/bin/php-config
make && make install
cp /usr/local/php/lib/php/extensions/no-debug-zts-20131226/mcrypt.so /usr/local/php/extension/mcrypt.so
php.ini添加，extension = mcrypt.so
/usr/local/apache/bin/apachectl restart
原文：http://www.cnblogs.com/ttiandeng/p/6561184.html