I'm kinda new to PHP.

I've got two different hosts and I want my php page in one of them to show me a directory listing of the other. I know how to work with opendir() on the same host but is it possible to use it to get access to another machine?

Thanks in advance

You could use PHP's FTP Capabilities to remotely connect to the server and get a directory listing:

// set up basic connection
$conn_id = ftp_connect('otherserver.example.com'); 

// login with username and password
$login_result = ftp_login($conn_id, 'username', 'password'); 

// check connection
if ((!$conn_id) || (!$login_result)) { 
    echo "FTP connection has failed!";
    exit; 
}

// upload the file
$upload = ftp_put($conn_id, $destination_file, $source_file, FTP_BINARY); 

// check upload status
if (!$upload) { 
    echo "FTP upload has failed!";
} else {
    echo "Uploaded $source_file to $ftp_server as $destination_file";
}

// Retrieve directory listing
$files = ftp_nlist($conn_id, '/remote_dir');

// close the FTP stream 
ftp_close($conn_id);

Try:

<?php

$dir = opendir('ftp://user:pass@domain.tld/path/to/dir/');

while (($file = readdir($dir)) !== false) {
    if ($file[0] != ".") $str .= "\t<li>$file</li>
";
}

closedir($dir);

echo "<ul>
$str</ul>";

I was unable to get the FTP suggestions to work so I took a more unconventional route, basically it yanks the html from the "Index of" page and extracts the filenames.

Index page:

Index of /files

Extraction code:

    $dir = "http://www.yoursite.com/files/";
    $contents = file_get_contents($dir);
    $lines = explode("
", $contents);
    foreach($lines as $line) {
        if($line[1] == "l") { // matches the <li> tag and skips 'Parent Directory'
            $line = preg_replace('/<[^<]+?>/', '', $line); // removes tags, curtousy of http://stackoverflow.com/users/154877/marcel
            echo trim($line) . "
";
        }
    }