Programming :: PHP - Connection To Remote Server To Edit File?

I have a webGUI in php where users can make certain settings. How can I edit a file on a remote server from my php webserver? Currently I use my FTP client, vsFTPd and a chrooted user in a specific directory where the file resides. I think this is pretty save as long a nobody else uses my FTPclient. How can I make changes to this file on the remote server from within my php-code on my webserver ?? (so that not I need to make the changes but my users can do it from a html-form) I found this but the credentials for the FTP-connection are plain :

<?php
$file = fopen ("ftp://loginasswd@server", "w");
if (!$file) {
echo "<p>Unable to open remote file for writing.
";

[code].....

I use https for the webGUI, but I guess this does not mean the connection to the remote server will be encrypted also ? Can I use my FTP-user (has no shell) from within php to edit the file ?