SSHFS files from one server to another

Question

I am trying to find the most secure way to transfer files from one server to another.

I have the following architecture:

Currently I am using the main user salamis in order to mount the directories.

The files in the original directory are created through a PHP file manager elfinder.

Unfortunately, I am not able to move, rename or delete any file from the mounted directory through PHP. I get permission denied.

1) Is it because I mounted the filesystem using salamis instead of www-data?

2) Is it secure to mount the filesystem on Server 2 as www-data ? If yes, how can I achieve that? www-data does not have a password and I cannot login using su -m www-data. I get authentication failure.

3) Can you think of a better architecture?

Answer 1

Like you suspected, it's probably an issue of uid/gid mapping. First you'll want to find the uid of www-data:

$ id www-data
uid=33(www-data) gid=33(www-data) groups=33(www-data)

Then you can ask sshfs to map like:

$ sshfs -o uid=33,gid=33 <remote> <local>

That may solve it.

As far as design goes, just beware that if your ssh connection drops, so goes the mounted file system. I'm not aware of an easy way to detect it (other than maybe a cron job that detects it). NFS might be more robust if it's an option. I do find sshfs quite handy, though.