Issue with $_SERVER["REMOTE_ADDR"] when Posting IP's - php

Question

So after a lot of testing, I've finally been able to get $_SERVER["REMOTE_ADDR"] to successfully post the IP into my MySQL Database
EXCEPT that it doesn't actually
post the right IP. It is only gathering the first 4 numbers and it's not putting periods after the sets of numbers. (I'm attempting to log IP's when users register accounts )
What could be the problem and how can I solve it?
Here is my Current Code:
<?php
session_start();
// variable declaration
$username = "";
$email = "";
$errors = array();
$_SESSION['success'] = "";
$ip = $_SERVER["REMOTE_ADDR"];
// connect to database
$db = mysqli_connect('host','user','pass','db')
or die('Error connecting to MySQL server.');
// REGISTER USER
if (isset($_POST['reg_user'])) {
// receive all input values from the form
$username = mysqli_real_escape_string($db, $_POST['username']);
$email = mysqli_real_escape_string($db, $_POST['email']);
$password_1 = mysqli_real_escape_string($db, $_POST['password_1']);
$password_2 = mysqli_real_escape_string($db, $_POST['password_2']);
$ip = mysqli_real_escape_string($db, $_POST = $_SERVER["REMOTE_ADDR"]);
// form validation: ensure that the form is correctly filled
if (empty($username)) { array_push($errors, "Username is required"); }
if (empty($email)) { array_push($errors, "Email is required"); }
if (empty($password_1)) { array_push($errors, "Password is required"); }
if ($password_1 != $password_2) {
array_push($errors, "The two passwords do not match");
}
// register user if there are no errors in the form
if (count($errors) == 0) {
$password = md5($password_1);//encrypt the password before saving in the database
$query = "INSERT INTO users (username, email, password, ip)
VALUES('$username', '$email', '$password', '$ip')";
mysqli_query($db, $query);
$_SESSION['username'] = $username;
$_SESSION['success'] = "You are now logged in";
header('location: index.php');
mysql_error();
}
}
// ...
// LOGIN USER
if (isset($_POST['login_user'])) {
$username = mysqli_real_escape_string($db, $_POST['username']);
$password = mysqli_real_escape_string($db, $_POST['password']);
if (empty($username)) {
array_push($errors, "Username is required");
}
if (empty($password)) {
array_push($errors, "Password is required");
}
if (count($errors) == 0) {
$password = md5($password);
$query = "SELECT * FROM users WHERE username='$username' AND password='$password'";
$results = mysqli_query($db, $query);
if (mysqli_num_rows($results) == 1) {
$_SESSION['username'] = $username;
$_SESSION['success'] = "You are now logged in";
header('location: index.php');
}else {
array_push($errors, "Wrong username/password combination");
}
}
}
?>
The code relating to $_SERVER["REMOTE_ADDR"];
$ip = $_SERVER["REMOTE_ADDR"];
$ip = mysqli_real_escape_string($db, $_POST = $_SERVER["REMOTE_ADDR"]);
$query = "INSERT INTO users (username, email, password, ip)
VALUES('$username', '$email', '$password', '$ip')";

Answer 1

You need to make sure that your database table column IP is (var)char of at least 15 characters, for example VARCHAR(15). (Or more than 15 for ipv6)
Also, why do you write $_POST = $_SERVER["REMOTE_ADDR"], and thus try to overwrite $_POST? Change that into just $_SERVER["REMOTE_ADDR"]!
Lastly, lookup parameterized queries.