poor man's dyndns

As many, I committed a low cost dyndns ; 

hourly, I call a server's url. if the server notices a change, it updates a DNS zone : 

root@clic12:/etc/cron.hourly# cat wgk

#!/bin/sh

IP=`ifconfig -a|grep 192|head -n 1|sed -e 's/  */|/g'|cut -d\| -f3`

URL="http://www.yoursite.net/zone.php"

wget -o /dev/null -O /dev/null "$URL" 2>&1 >/dev/null

wget -o /dev/null -O /dev/null "$URL?n=guy&ip=$IP" 2>&1 >/dev/null

and the php side (can manage many dyndnses): 

//print_r($_SERVER);

$n=preg_replace("/[^a-z]/","",$_REQUEST["n"]);

if ($n)

 foreach(explode("\n",file_get_contents("zone.txt")) as $l)

   if (preg_match("/ $n /",$l)) $m=preg_replace("/^.* $n /","",$l);

if ($_REQUEST["a"]) die(file_get_contents("zone.txt"));

if ($_REQUEST["d"])

        die("ok".file_put_contents("zone.txt",strftime("%D %T reset
\n")));

if (!$n) die("list,reset");

$q=strftime("%D %T $n ".$_REQUEST["ip"]." ".$_SERVER["REMOTE_ADDR"]."
");

file_put_contents("zone.txt",$q."\n",FILE_APPEND);

$q=preg_replace("/^.* $n /","",$q);

if ($q == $m) die("ok same ip");

file_put_contents("zone.txt","***********NEWIP*******\n".$q."\n",FILE_APPEND);

if ($n=="guy")

        passthru("sudo /root/scripts/named_dyndns.sh yoursite.net adsl ".$_SERVER["REMOTE_ADDR"]);

?>.

and named_dyndns.sh + domain + subdomain + ip

#!/bin/sh

domain=$1

key=$2

ip=$3

if [ "$ip" = "" ];then echo "$0 domain key ip";exit;fi

dmx=/var/named/chroot//etc/named.xtra

sed -i $dmx -e "s/^$domain:$key IN A .*$/$domain:$key IN A $ip/"

/root/bin/named_make_domxtra2zon.pl $domain

after, this is your own domain/named/zone system, 

that recreates a zonefile and reload named