Copying File Between Servers with PHP or Shell Commands
 

I have a DMZ set up with a web server (Ubuntu 11.04) and an application server (Ubuntu 11.10). I can call php files on one server from the other using LAMP. I have set things up so a user can upload files. The files are uploaded to a folder /var/www/dropbox on the web server. I would like to be able to add php code to copy the files from the web server to the application server. What would be the best way to do this in the PHP code? I could use a shell command and use something like

but do not know what shell command would be best to use.

Any assistance would be greatly appreciated,
Peter.

I would not suggest doing this at all due to the security issues that stem from running arbitrary commands on demand. I would recommend looking at a cron job or something equivalent to push files to their destination asynchronously.

It seems that Cron is for scheduling tasks. I would want the clients files to be copied pretty well immediately so that they can start processing them with the software I have written. Would there be security issues in my copying using a bash file that anyone can execute but noone had read persmission for? The files would be automatically checked before and after the copy.

Thanks,
Peter.

If you've got method for auto-checking a shell file for exploits that actually works, I'd very surprised .. I believe the general case is unsolvable.

In any case, a shell file requires read+execute permissions to run directly (eg ./my.sh). You could use
which only requires that the sh file be readable.

Currently the files that are uploaded must be one of two formats. If neither of those formats, the files is rejected.

If I did not want to use a file with read permissions, could I write an executable in C++ and make a system call? If so, what would be the best system call to use?

Thanks,
Peter.

Depends on exactly what you want it to do.
A binary executable generated from C code only requires 'x' perm to run.

A script file eg bash, perl etc either requires 'rx' if run directly, or at least 'r' if run by another exe eg '/bin/bash my.sh' or '/usr/bin/perl my.pl'.
IE, the calling exe needs to be able to read the content in order to action it.

To copy files between systems I recommend scp or sftp using ssh-auth-keys for automatic processes.

I'm going to assume that you trust the file contents, obviously...

HTH
:)

Hi,

I know I'm jumping into this thread a bit late, but I've something to add.
It looks like what you want is actually "incron", which is similar to cron but it performs actions based on filesystem events instead of time(s).

HTH,

Evo2.

I tried

and got

When I enter


on 192.168.1.10, I get, among other things,
I am trying to copy from 192.168.1.5

LOL. Not entirely although they should be from registered users. I plan to have several layers of checks for what is uploaded.

Thanks,
Peter.

Thank you for the reply. would that be better than rcp?

Thanks,
Peter.

No, you would use it to automatically run a script to copy the files that appear on disk.
The script which does the copying should probably use scp or rsync with ssh. Authentication should be done using rsa public/private keys. rcp is insecure.

Evo2.

Sorry. I meant to say scp, not rcp.

Thanks,
Peter.