Yes you can surely get into IIT for MSc without doing  you BSc degree there.

For that you need to give an entrance exam named IIT-JAM i.e. Joint Admission test for Msc. This exam is  fully online and conducted once a year. The exam duration is 3 hours.

You should have a Bachelors degree with 55% minimum marks taking consideration of all subjects of undergraduation course.

There is no age limit for this exam. You need to fill the online application form then pay application fees then download admit card then appear for exam on the date on admit card then check results & see if you have qualified.

Six test papers are conducted namely; Mathematics Statistics, Physics, Biotechnology, Chemistry ,Geology,

Hope you like the answer. Thank you