If you want to know more about portal-ext.properties

 1-portal-ext.properties

http://docs.oracle.com/cd/E19957-01/820-6878/giata/index.html

https://www.google.co.in/url?sa=t&rct=j&q=&esrc=s&source=web&cd=9&cad=rja&uact=8&ved=0CFQQFjAIahUKEwi0lZvU_4TIAhVITY4KHfVFDMo&url=http%3A%2F%2Fdocs.oracle.com%2Fcd%2FE19957-01%2F820-6878%2Fgiata%2Findex.html&usg=AFQjCNECinWN4s8mSE6i3nwWsk29bHZEvA&bvm=bv.103073922,d.c2E