Web Development

Hi Again.

This came up again today. ::1.

In my /etc/hosts

Code:

## # Host Database 
# # localhost is used to configure the loopback interface 
# when the system is booting. 
Do not change this entry.
 ## 127.0.0.1 localhost 
255.255.255.255  broadcasthost 
::1 localhost

It says DO NOT CHANGE THIS ENTRY.

The code I am running is checking ip addresses and then blocking one.
The problem is that the language construct die(); does Not Kill the page.
The HTML 'welcome' text still shows.
It is again just a learning exercise so I am echoing and killing the page at certain points to see what shows up on the browser. The following code should die() and not show the word 'welcome' coded between HTML tags but it does show up.

Code:

Index.php

<?php 
require 'conf.inc.php';
foreach($ip_blocked as $ip){
    if ($ip==$ip_address){
     die();
}
}
?>
<h1> welcome</h1>

conf.inc.php

<?php 
$ip_address = $_SERVER['REMOTE_ADDR'];
$ip_blocked = array('127.0.0.1', '100.100.100.100');
?>

I added this code - someone suggested this and I was helpful although I do NOT fully understand how to interpret.

Code:

$ip_address = $_SERVER['REMOTE_ADDR']; 
$ip_blocked = array('100.100.100.100'); 
var_dump($ip_blocked); 
var_dump($ip_address);

Output: I typed this in.

Code:

array(2) { [0]=> string(9)  "127.0.0.1" [ 1] => string(15) "100.100.100.100" } string(3) "::1"  "::1"

see that ::1.... i had that question a while back.
when I use this code....

Code:

foreach($ip_blocked as $ip) { 
echo $ip.'<br>';

i get this output:

Code:

127.0.0.1 100.100.100.100

not ::1

I am confused.
Is this why I am running into trouble with my testing ?

Any clarification will be helpful.
Thanks again.

OK, very short introduction to networking basics:

"IP" is the basis for all internet communication (hence the name, "Internet Protocol"). For some aspects of this protocol it is necessary that a host can communicate with itself, just like it would be another host (like you look at yourself in the mirror). For this there is a special address, which does not belong to a certain host at all, but to each host: 127.0.0.1. This is called the "loopback" address every host can use this to connect internally to itself.

So far, so good. Alas, the classical IP (which, in fact, is "IP v4") is getting to its limits in many ways. One of the aspects where IP (v4) is starting to experience problems is the address room: the classical 4-byte address is simply not providing enough numbering space to accomodate for all the devices needing to access the internet (which needs a unique IP address as a prerequisite). Therefore IP v6 (or "IPng - next generation"; don't ask what happened to v5) provides a much bigger address space. In this new address space "::1" is the new loopback address.

I suppose you need to either deactivate IP v6 somewhere and/or activate "IP v4 only" to get rid of the "::1", because most probably PHP, as a network-aware language, automatically translates "127.0.0.1" to "::1" back and forth.

I know this won't help you in finding the problem directly, but at least you should now know what to look for and why.

I hope this helps.

bakunin

Thanks again bakunin !
Very helpful again.
You clarifications are definitely is filling in some of the pieces to this puzzle for me.