Firstly property name you are using in hibernate config is incorrect it should be hibernate.cache.
use_second_level_cache instead of
user_second_level_cacheCode:
<property name="hibernate.cache.use_second_level_cache">true</property>
Second you need to check which version of hibernate you are using
For Hibernate 3.3 and higher
Code:
<property name="hibernate.cache.region.factory_class">
net.sf.ehcache.hibernate.EhCacheRegionFactory</property>
And for Hibernate 3.0 - 3.2
Code:
<property name="hibernate.cache.provider_class">
net.sf.ehcache.hibernate.EhCacheProvider</property>