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

[Ivica Ico Bukvic]

On 10/10/2014 04:01 PM, Joe Hartley wrote:
> 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'
>
Thanks for this but I thought that is what ForceCommand internal-sftp -u 
0222 does (and it does change file permissions except that even if 
permissions are 000 I can still delete the file through sftp.

Subsystem is

Subsystem sftp /usr/lib/openssh/sftp-server

-- 
Ivica Ico Bukvic, D.M.A.
Associate Professor
Computer Music
ICAT Senior Fellow
DISIS, L2Ork
Virginia Tech
School of Performing Arts - 0141
Blacksburg, VA 24061
(540) 231-6139
ico at vt.edu
www.performingarts.vt.edu
disis.music.vt.edu
l2ork.music.vt.edu