How to get into such companies ? They only hire from IIT/NITs right
Well, many of these companies do visit top campuses and offer high pay packets there, but its not the end of the line for the rest as these companies also recruit experienced people in off campus drives where your college, degree, company that you work for don't matter as much as your knowledge/skills.
Let me just tell you that out of the 60+ people I interviewed for a job at my company over the last 6 months, only two people landed with offers and neither of them were from IIT's and one of them didn't even have an Engg degree. Among those rejected, there were at least 8 people who had a B.Tech/M.Tech from an IIT. So yeah, companies don't always blindly look for an IIT stamp of approval on your resume when hiring.