Log connecting clients' IP, port, user agent, and HTTP referer with a timestamp of the connection. MySQL storage preferred.

connectionlog.php

<?php

// For now file storage requires that the file specified is created already and chmodded to allow writing.

/**
* Connection info logging script created by Xeru
*
* Website: https://xeru.me
* Twitter: https://twitter.com/Xeru_
* GitHub: https://github.com/exec
*
*/
 
// Message user sees. Set to "" if you don't want to display a message, ideal for including in external scripts.
$message = "<h1>404 Not Found</h1>";

// Set variables
$date = new DateTime(); // Date+time variable
$rdate = $date->format('Y-m-d H:i:s'); // Normalizing it
$protocol = $_SERVER['SERVER_PROTOCOL']; // what protocol the client is connecting from
$ip = $_SERVER['REMOTE_ADDR']; // the IP address of the connecting client.
 
// If connecting through Cloudflare, rely on Cloudflare's connecting-IP header to get IP, otherwise check server header.
if(!isset($_SERVER['HTTP_CF_CONNECTING_IP'])) {
  $ip = $_SERVER['REMOTE_ADDR'];
} else {
  $ip = '[cloudflare reports] '.$_SERVER['HTTP_CF_CONNECTING_IP'];
}
 
$port = $_SERVER['REMOTE_PORT']; // connecting port of the client. Not useful usually but can be interesting.
$agent = $_SERVER['HTTP_USER_AGENT']; // Unreliable to find a connecting client's browser, but can be useful sometimes.
$href = $_SERVER['HTTP_REFERER']; // If you're linking this to someone directly, it will usually be nothing.
$hostname = gethostbyaddr($_SERVER['REMOTE_ADDR']); // Attempt to resolve hostname from IP address.

$type = "mysql"; // "file" or "mysql"

// MySQL storage config
$db_host = 'localhost';
$db_username = 'records';
$db_password = 'records';
$db_database = 'records';

// file storage config
$file = "log.txt"; // Should rename this in case someone looks for the log file. Or protect with htaccess.
 
// If you don't know what you're doing leave this alone pls
if(!empty($type) && $type == "file") {
  if(is_writable($file)) {
    $fh = fopen($file, 'a');
    if(filesize($file) < 32) {
      fwrite($fh, " _____________________\n");
      fwrite($fh, "|                     |\n");
      fwrite($fh, "| PHP LOGGER  BY XERU |\n");
      fwrite($fh, "|_____________________|\n\n");
      fwrite($fh, " BEGIN LOGFILE ".$file."\n");
      fwrite($fh, " _____________________\n");
      fwrite($fh, "|\n");
    }
    fwrite($fh, '| Connection from '.$ip.' at '.$date->format('Y-m-d H:i:s')."\n");
    fwrite($fh, '| Hostname: '."".$hostname ."\n");
    fwrite($fh, '| Port: '."".$port ."\n");
    fwrite($fh, '| User Agent: '."".$agent ."\n");
    fwrite($fh, '| HTTP Referer: '."".$href ."\n");
    fwrite($fh, "|_____________________\n");
    fclose($fh);
    echo $message;
  } else {
    chmod($file, 0777); // attempt to chmod the file to make it writable.
    die("<pre>Content could not load. Please try again in a few seconds.\n");
    die("If you are the owner of this site, please adjust file permissions to allow writing to the file specified in config.</pre>");
  }
} elseif(!empty($type) && $type == "mysql") {
  $sqlconn = mysqli_connect($db_host, $db_username, $db_password, $db_database);
  if (mysqli_connect_errno()) {
    printf("Could not connect to MySQL database: %s\n", mysqli_connect_error());
    exit();
  }
  mysqli_query($sqlconn, "CREATE TABLE IF NOT EXISTS records.`logs` (
   IP TEXT( 16 ) NOT NULL,
   DATE TEXT( 30 ) NOT NULL,
   HOSTNAME TEXT( 255 ) NOT NULL,
   PORT INT( 6 ) NOT NULL,
   USERAGENT TEXT( 255 ) NOT NULL,
   HTTPREFERER TEXT( 255 ) NOT NULL
  )");
  mysqli_query($sqlconn, "INSERT INTO records.`logs` VALUES (
    '$ip',
    '$rdate',
    '$hostname',
    '$port',
    '$agent',
    '$href'
  )");
  mysqli_close($sqlconn);
  echo $message;
}