php - Update IP button twice a day option? -

i'm trying make secure web-based login tool software, , it, need "one ip login" per account. that, need make user able update it's ip twice day.

<h2><strong>controle</strong> de acesso</h2> <div>     <div class="portlet-body">         <form method="post">             <div class="form-group">                 <label>activated ip</label>                 <input type="text" class="form-control" name="ipsaved" placeholder="" value="<?php echo $userinfo['iplib']; ?>" disabled readonly/>             </div>         </form>         <div class="form-group">             <label>actual ip:</label>             <label><?php echo $_server["remote_addr"]; ?></label>         </div> </div> 

i need know how can make button update activated ip actual ip, can done twice day

how can make button, , make able 2 changes day?

you need store persons ip somewhere such database when tries login , ip doesn't match whats in database wont work. can store date of when ip last stored , update every 12 hours or something.

but method isn't considered secure because easy mimic ip address of else. can setup 2 factor authentication when person tries login sent sms or email 4-6 character verification code , have 20 minute enter able login.