Is it ok to distribute an OS with a passwordless ssh root access... ?

[levi]

But there are better debugging interface alternatives more suitable for connecting to your machine (serial/telnet).
Having SSH implies that it's secure somehow, which in this case is not.

Well, it's still secure in that it protects that communications from an outside spy. Unfortunately if the connection is between a cracker and your device, it's securing a bad connection.

I'm not sure serial/telnet are better other than providing developers access though. They could be a better fit but only in weird situations where you have a cabinet full of TTL logic and no PC. Even a windows PC these days can get you into a ssh port and optionally script the test run.

 

[TeDaDeS]

Example: If you develop a driver and put it on your SD-card into a raspberry-pi. you might not see anything work. If you want to debug it's easy to have a serial port connection, as it's pretty basic to setup and check. You can do it with a logic analyzer / oscilloscope or a serial connection to your PC with telnet. Running SSH already requires a lot be working.

Securing a connection to not be monitored wouldn't be relevant as you shouldn't be using passwordless SSH in public, everybody can connect to your box then.
If you are using it at home there wouldn't be need to secure your connection, you probably wouldn't as it's much easier to debug unencrypted connections.
Obviously you would never use these in a public network as it's unsecure, even worse then using no password, but a firewall would probably block these ports anyway unlike SSH.

 

[levi]

That's true. They already have kindof serial out over the debug/charging port which at the time of writing to the best of my knowledge is planned to remain enabled even after release. You can presumably use that to see if the device is up enough to present a login prompt. If you've got that and a half-reliable file system though, you can be largely sure sshd will be running, and you can use sshd to develop further with a more reliable connection (although serial over USB is presuambly a lot more reliable than the old RS232 connections which could be disrupted by the wrong air pressure at times).