Limiting file size with sftp?

MrUmunhum · 03-24-2009, 04:34 PM

Hi group,

I need to limit the size of files transferred using sftp. Any pointers? Can't use ulimit, that limits total disk usage.

anomie · 03-24-2009, 04:45 PM

Are you sure you can't use ulimit..? From manpages for bash_builtins(1):

Quote:

ulimit
...
-f The maximum size of files written by the shell and its
children

Example:

Code:

$ ulimit -f
unlimited

$ ulimit -S -f 10

$ cat /dev/zero > foo
File size limit exceeded

$ du -h foo 
16K     foo

----------

Edit: Or are you trying to say you want the restrictions to only apply for sftp (and not for a regular shell session)?

unSpawn · 03-24-2009, 05:00 PM

Similar to HTTP POST uploads, as far as I know, there is nothing in the protocol itself that precedes the stream saying "look, here comes a 4GB file".

MrUmunhum · 03-25-2009, 12:49 PM

Quote:

Originally Posted by anomie

Are you sure you can't use ulimit..? From manpages for bash_builtins(1):

Example:

Code:

$ ulimit -f
unlimited

$ ulimit -S -f 10

$ cat /dev/zero > foo
File size limit exceeded

$ du -h foo 
16K     foo

----------

Edit: Or are you trying to say you want the restrictions to only apply for sftp (and not for a regular shell session)?

Yes, I want to apply the rule to each file transfer of a continuosly running sshd for a special scp-only daemon on a server.

An overview of my set up.

A. multiple clients that use sftp to transfer files to Hub
B. Hub runs scp-only daemon that accepts files from clients and then retransmit them to other clients.
C. other clients that accept files from Hub

I want to limit the size of the files that the Hub (B) will accept.

I will test your suggestion of usings ulimit.

MrUmunhum · 03-30-2009, 04:18 PM

Quote:

Originally Posted by anomie

Are you sure you can't use ulimit..? From manpages for bash_builtins(1):

Example:

Code:

$ ulimit -f
unlimited

$ ulimit -S -f 10

$ cat /dev/zero > foo
File size limit exceeded

$ du -h foo 
16K     foo

----------

Edit: Or are you trying to say you want the restrictions to only apply for sftp (and not for a regular shell session)?

I tried using ulimit but it did not work for sftp/scp file transfers. It does work for local command like 'cp', 'cat', etc.

anomie · 03-30-2009, 04:35 PM

Hmm. And this doesn't seem like a candidate for quotas. I am not sure what else to suggest.