Greetings:

   This problem may occur with older versions of Solaris, but I noticed it
under Solaris 10.  It appears that unless a user has a shell that allows
interactive logins, he cannot connect to a machine using sftp.  We have a
Solaris host that we normally assign a login shell of /bin/date so that the
user cannot log in interactively.  But when that user tries to use sftp from
another host, he gets this message: "Couldn't read packet: Bad file number".
If I assign him a shell that can log in interactively, it works.  Can someone
suggest a workaround?  I would like for students to be able to use sftp, but
I do not want to allow interactive logins.  Thanks...

Jim McCullars

On 13 Apr 2006 15:59:56 -0500 in <e1me4c$qf8$1@info2.uah.edu>,
Jim McCullars said something similar to:
>     This problem may occur with older versions of Solaris, but I noticed it
>  under Solaris 10.  It appears that unless a user has a shell that allows
>  interactive logins, he cannot connect to a machine using sftp.  We have a
>  Solaris host that we normally assign a login shell of /bin/date so that the
>  user cannot log in interactively.  But when that user tries to use sftp from
>  another host, he gets this message: "Couldn't read packet: Bad file number".
>  If I assign him a shell that can log in interactively, it works.  Can someone
>  suggest a workaround?  I would like for students to be able to use sftp, but
>  I do not want to allow interactive logins.  Thanks...

The ssh server is invoking the sftp-server program through the user's shell,
e.g.:  '/bin/sh -c /usr/lib/ssh/sftp-server' for a user with /bin/sh as his
login shell.  So in order to restrict the account to sftp only, you need
to set the user's shell to a program which will handle -c /path/to/sftp-server
properly, but simply exit if invoked with any other arguments or no arguments
at all.

Mike Delaney (mdelan@computer.org) wrote:

: The ssh server is invoking the sftp-server program through the user's shell,
: e.g.:  '/bin/sh -c /usr/lib/ssh/sftp-server' for a user with /bin/sh as his

   Ah, didn't realize that's how sftp works.  Thanks for the heads-up.

Jim McCullars