[LAU] OT: seeking help with uploading files via sftp and preventing their subsequent deletion

[Joe Hartley]

On Fri, 10 Oct 2014 15:51:29 -0400
Ivica Ico Bukvic <ico at vt.edu> wrote:
> So, what I did so far is change /etc/ssh/sshd_config so that sftp 
> chroots said user's home dir, and prevents access via ssh. I also 
> created a sftponly group and added the user to it. I adjusted home dir 
> permissions and created a subfolder "submissions" where users can submit 
> their projects. Finally, I added umask to strip permissions from 
> uploaded files.
> 
> So, the /etc/ssh/sshd_config has the following entry
> 
> Match Group sftponly
> ChrootDirectory /home/%u
> ForceCommand internal-sftp -u 0222
> X11Forwarding no
> AllowTcpForwarding no

What's your subsystem line look like?  You can force the umask there with
the -u directive.  Example:
Subsystem sftp /usr/libexec/openssh/sftp-server -u 0002

If your sftp-server does not support -u then you can get the same effect
with this:
Subsystem sftp /bin/sh -c 'umask 0002; /usr/lib/openssh/sftp-server'

-- 
======================================================================
       Joe Hartley - UNIX/network Consultant - jh at brainiac.com
 Without deviation from the norm, "progress" is not possible. - FZappa