Assam & Meghalaya you do not need any permit.
Nagaland had done away with permit in 2011:
Sikkim: you would need permit - this can be obtained from Sikkim House in Kolkata near Maidan Metro/Under ground train station
Mizoram you would need to obtain permit - if you are traveling in group of at least 4 person you can obtain it from Kolkata, if you are alone you must obtain it from Ministry of Home Affairs in Delhi:
Arunachal Pradesh: Yes you do need a permit.
Manipur is a disturbed place at the moment.
In my opinion it is better to get the permit from Delhi.