1

I'm trying to get sftp to give me a umask of 002 but it keeps behaving like the umask is 022. How do I get it to do that?

Red Hat 7.4

/etc/ssh/sshd_config has the line:

Subsystem sftp internal-sftp -u 002

I've also tried

Subsystem sftp internal-sftp -u 0002

After each change I make to sshd_config I issue the following command:

sudo systemctl restart sshd.service

Then in a separate window I log into sftp.

Once I've uploaded the file in sftp, then "ls -Fla" in the shell session returns:

drwxrwsr-x. 2 [myID]  [myGroup]         32 Dec 28 17:37 ./
drwxrwxr-x. 4 [siteID] [siteGroup]      50 Dec 26 18:44 ../
-rw-r--r--. 1 [myID]  [myGroup]    9173334 Dec 28 17:37 [myUploadedFile]

(last line having r-- as the group permission)

where I would expect:

drwxrwsr-x. 2 [myID]  [myGroup]         32 Dec 28 17:37 ./
drwxrwxr-x. 4 [siteID] [siteGroup]      50 Dec 26 18:44 ../
-rw-rw-r--. 1 [myID]  [myGroup]    9173334 Dec 28 17:37 [myUploadedFile]

(last line having rw- as the group permission)

I've also tried

Subsystem sftp internal-sftp -u ug=rwx

but that one causes sftp to close the connection. At least it confirms that I'm updating the right configuration file.

  • Are you sure the remote umask is the problem? Your SFTP client may be setting explicit permissions on the remote file. – Kenster Dec 29 '18 at 19:09
2

Notice that umask values only reduce permissions, never adds them.

So if your local file was permission 0644 (-rw-r--r--) then the umask will not add a group write flag. The umask will remove "other write"; so if your local file was 0666 then the remote would be 0664.

If you want to ensure the remote file has group write then you might want the -m 664 flag instead.

0

In your sshd config file, try setting "ForceCommand" on your groups

Match Group {GROUP_NAME}
   ForceCommand internal-sftp -u 0002 

Restart your sshd process for the new settings to take effect

  • Do you have some reason to believe the normal subsystem configuration isn't working here? – Kenster Dec 29 '18 at 19:10

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