[scponly] failed: /usr/libexec/openssh/sftp-server with error No such file or directory(2)

[Peter Weil]

I've done about a half dozen scponly installs, but not for over a  
year. I'm getting this error when I try to connect for my test user  
(this is from the secure log):

Mar 10 15:52:27 ruby scponly[29117]: failed: /usr/libexec/openssh/sftp- 
server with error No such file or directory(2) (username:  
kahewson(509), IP/port: 144.92.105.153 49501 22)

sftp-server does exist in the chroot directory (and the path is  
correct), and I think all of the permissions are correct. I pretty  
much copied what I have from a previous install, and can't find any  
differences. I also added /dev/null to the chrott directory.

I also did an strace, which, while largely unreadable, did mention  
some missing files, such as /etc/localhost. I found this odd, as my  
previous installs (which work) don't have these files. I copied them  
over the the chroot directory any, but it didn't help. I still suspect  
that has something to do with the sftp-server file, or a typo  
somewhere, but I'm running out of ideas.

The only difference I can see between installs is that the new one  
(both are on Fedora) installed scponlyc in /usr/local/sbin instead of / 
usr/sbin -- I don't know why this was the case, but I don't see why it  
would make much difference as long as I point to the correct path in / 
etc/shells and in /etc/passwd.

Does anyone else have any suggestions? I suspect that this is not an  
uncommon problem, but I haven't been able to find the right answers yet.

Thanks, Peter

------------------------------

Here is the complete secure log entry for a failed login:

Mar 10 15:52:27 ruby sshd[29114]: Accepted password for kahewson from  
144.92.105.153 port 49501 ssh2
Mar 10 15:52:27 ruby sshd[29114]: pam_unix(sshd:session): session  
opened for user kahewson by (uid=0)
Mar 10 15:52:27 ruby sshd[29116]: subsystem request for sftp
Mar 10 15:52:27 ruby scponly[29117]: chrooted binary in place, will  
chroot()
Mar 10 15:52:27 ruby scponly[29117]: 3 arguments in total.
Mar 10 15:52:27 ruby scponly[29117]: 	arg 0 is scponlyc
Mar 10 15:52:27 ruby scponly[29117]: 	arg 1 is -c
Mar 10 15:52:27 ruby scponly[29117]: 	arg 2 is /usr/libexec/openssh/ 
sftp-server
Mar 10 15:52:27 ruby scponly[29117]: opened log at LOG_AUTHPRIV, opts  
0x00000029
Mar 10 15:52:27 ruby scponly[29117]: determined USER is "kahewson"  
from environment
Mar 10 15:52:27 ruby scponly[29117]: retrieved home directory of "/ 
altroot//home/kahewson" for user "kahewson"
Mar 10 15:52:27 ruby scponly[29117]: Setting homedir to /home/kahewson
Mar 10 15:52:27 ruby scponly[29117]: chrooting to dir: "/altroot"
Mar 10 15:52:27 ruby scponly[29117]: chdiring to dir: "/home/kahewson"
Mar 10 15:52:27 ruby scponly[29117]: setting uid to 509
Mar 10 15:52:27 ruby scponly[29117]: processing request: "/usr/libexec/ 
openssh/sftp-server"
Mar 10 15:52:27 ruby scponly[29117]: Using getopt processing for cmd / 
usr/libexec/openssh/sftp-server  (username: kahewson(509), IP/port:  
144.92.105.153 49501 22)
Mar 10 15:52:27 ruby scponly[29117]: running: /usr/libexec/openssh/ 
sftp-server (username: kahewson(509), IP/port: 144.92.105.153 49501 22)
Mar 10 15:52:27 ruby scponly[29117]: about to exec "/usr/libexec/ 
openssh/sftp-server" (username: kahewson(509), IP/port: 144.92.105.153  
49501 22)
Mar 10 15:52:27 ruby scponly[29117]: failed: /usr/libexec/openssh/sftp- 
server with error No such file or directory(2) (username:  
kahewson(509), IP/port: 144.92.105.153 49501 22)
Mar 10 15:52:27 ruby sshd[29114]: pam_unix(sshd:session): session  
closed for user kahewson


--
Peter Weil, Web Developer
University Communications
University of Wisconsin-Madison
Phone: 608-262-6538
Email: plweil at wisc.edu