[quesera]

Agree that ssh was modeled after rsh. But rsh was a different kind of security problem, which wasn't really relevant on the wider Internet.

ssh solved the "pass credentials in cleartext over untrusted networks" problem. Consequently it replaced telnet and ftp. It also duplicated the functionality of rsh and rcp, so those protocols became irrelevant. But that was not the important goal.

> Kerberos solved authentication for free,

This made me laugh. Kerberos didn't do anything for free. :)

Even in Athena, Kerberos had reliability problems. In the wider world, it was very hard to find a well-managed Kerberos implementation. Things are different now!