What are some potential pitfalls when using IP-based security measures in PHP forms?

One potential pitfall when using IP-based security measures in PHP forms is that IP addresses can be easily spoofed or changed, rendering the security measure ineffective. To address this issue, it is recommended to combine IP-based security with other forms of authentication, such as user credentials or tokens. 

// Example of combining IP-based security with user credentials
$allowed_ips = array('192.168.1.1', '10.0.0.1');
$user_ip = $_SERVER['REMOTE_ADDR'];

if(in_array($user_ip, $allowed_ips) && isset($_POST['username']) && isset($_POST['password'])) {
    // Perform form processing logic
} else {
    // Redirect or display an error message
}

Keywords

IP-based security PHP forms validation filtering whitelist

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