What are some common pitfalls to avoid when working with remote file access in PHP?

Common pitfalls to avoid when working with remote file access in PHP include not properly sanitizing user input before using it in file paths, not verifying the existence and permissions of remote files before accessing them, and not using secure methods of file transfer such as SFTP or HTTPS. 

// Example of properly sanitizing user input before using it in file paths
$filename = filter_var($_GET['filename'], FILTER_SANITIZE_STRING);
$path = '/path/to/files/' . $filename;

// Example of verifying the existence and permissions of a remote file before accessing it
if (file_exists($path) && is_readable($path)) {
    $file_contents = file_get_contents($path);
    // Process file contents here
} else {
    echo 'File does not exist or is not readable.';
}

// Example of using secure methods of file transfer such as SFTP
$connection = ssh2_connect('example.com', 22);
ssh2_auth_password($connection, 'username', 'password');
$sftp = ssh2_sftp($connection);
$remote_file = 'sftp://'.intval($sftp).'/path/to/remote/file';
$contents = file_get_contents($remote_file);
// Process file contents here

Keywords

file_get_contents fopen allow_url_fopen security remote file inclusion

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