Unpaid internships and indentured servitude

So, recently I started looking for my first software job. The first offer I received was from a company looking for an intern. The internship had the following conditions: 1) the first 3 months of it are unpaid 2) you have to sign a contract after the 1st month of it that obligates you to stay at the company 2 years after the internship is ended. I rejected it because I felt like you never know what that company may turn out to be. For example, it may try to exploit you and pay you the bare minimum for the job you're doing preventing your career growth and your only option may be to wait for that contract to expire and then start looking for a higher position at another company. I'd like to ask your opinion about:

• unpaid internships
• internships that obligate you to stay at the company for 1 or 2 years once the internship is ended
• companies that follow both of these practices