rssh frequently asked questions

Q: What is rssh?

A: See the rssh homepage.

Q: Why did you write this software?

A: Mainly, because the question of how to restrict access to scp or sftp only kept coming up on a few different mailing lists I was on at the time... Several people made some suggestions (like using a shell script as the user's shell) which sort of work, but aren't terribly secure or reliable. The commercial SSH product has a program to do this, but OpenSSH does not. Joe Boyle has a similar program called scponly, which at the time I looked at it had some security problems, though they have since been fixed... It does currently have some functionality that rssh does not (namely it works with WinSCP; see below), and some that it never will have (more on that in a moment). Obviously I prefer the way I've implemented my program, or else I wouldn't have written it.   =8^)

I did not write this program for my own use; I do not use it today, nor have I ever (though obviously I would if the occasion arose). At the time, I was bored, and I thought this project would be amusing and educational, as well as fill a gap. Please keep this in mind when asking for support. Odds are I'll give it pretty quickly if I've got a free minute, but what you get is what you get, and I won't loose sleep over slow response time. You've been warned.

Q: Will you send me e-mail when you release an update?

A: Are you serious? I do have a life, you know... If you want to be notified of new releases of rssh, visit its freshmeat page, where you can subscribe to new releases. Whenever I release a new version, I update freshmeat, so you'll be notified if you subscribe.

Q: Is support for running rssh in a chroot jail planned?

A: Yes. With the 2.0 release, chroot jail support was included. In 2.1 it is configurable on a per-user basis.

Q: I'm not compiling with GCC and rssh won't compile?

A: Upgrade to the latest 2.1.x release, and try again. Let me know if you still have problems.

Q: Why can't I compile on Irix?

A: Upgrade to the latest 2.1.x release, and try again. Let me know if you still have problems.

Q: Why does rssh keep dumping core on me?

A: If you built rssh for Solaris, and are not using rssh with a version of OpenSSH >= 3.5, then by default the configure script will try to build statically linked binaries. This is next to impossible on Solaris, due to brain damage in Sun's C libraries. Upgrade to OpenSSH 3.5 to fix the problem securely. Or, if that's not an option, you can run the configure script with --disable-static, but this opens a security hole.

If you are already using OpenSSH 3.5 or later, and/or you are not building on Solaris, then you probably installed rssh incorrectly. You are also probably using it with chroot jails. Be sure to read the man page and the INSTALL file, and also the CHROOT file if you are using rssh with chroot jails. If you don't have your jail set up properly, you will definitely see lots of broken behavior, including core dumps.

Q: I set up rssh and it's great! But, can't you also add the ability to run command x?

A: Well, no. Or, actually yeah I could, but I don't want to. There are several reasons for this, and I think they're good ones. The purpose of rssh is to allow system administrators to allow users access to a server via either scp or sftp, or both. This design is simple and clean, and very easy to keep secure.

Aside from the fact that if I added the ability to run all of the x's in people's requests, what you'd end up with would essentially be bash, once you start adding additional commands, or the ability to run arbitrary commands, it becomes much harder, which is to say nearly impossible to keep secure. Too many possible variables. Also, rssh has the ability to chroot. This requires that the binary (or at least a helper program) is SUID root. This only compounds the problem; one little mistake would mean a root compromise.

So sorry, but no. As far as I'm concerned, it defeats the purpose of having the thing in the first place, and also utterly destroys the simplicity of the code. Maybe what you need is some other form of secure shell. Or, feel free to take the code for rssh and modify it any way you like. But please stop asking for this feature, 'cuz it ain't gonna happen.

Oh, another reason is because I'm lazy... Get over it!   =8^)

Q: I support Windows users who can't/won't learn how to use SSH command-line tools. Can't you make rssh work with WinSCP?

A: Absolutely not. It's not because I think Windows is a crappy operating system that should never be used whenever alternatives exist (though that's basically true)... This ties in with the previous question. WinSCP is a bit of a hack (though a good one -- no offense meant to the author) which provides a GUI front end to command-line ssh tools. It requires that the user be able to run commands through ssh to manipulate the file system. There's already a way to do this... with sftp. In order to make rssh work with WinSCP, I'd have to modify rssh to be able to run a number of other commands. This is, IMO, the wrong approach.

If you want a GUI front end that works with rssh, that I can provide. Or at least tell you where to get it. Check out FileZilla, which is freeware, or SecureFX, which is commercial. Thanks to Paul C. Bryan for providing me with this information. There are also a number of commercial FTP clients that now also support sftp. WS-FTP Pro is one. There are others. Google is your friend.