[Nh-pm] Zoneedit autoupdate

[Ben Boulanger]

Howdy,
	After finding zoneedit's dynamic updating, I decided to write a 
perl script to auto update the records I host there whenever my IP address 
changes.  The problem I had is that I use a linksys router to do NAT and 
give me wireless.  So, after some noodling on it, I came up with this 
script to scrape the public IP address out of the linksys's Status page.  
I know that I'd heard of some folks using zoneedit on these lists, so I'm 
sending it around.  Feel free to improve/comment.  No warranty is given!

Ben



-- 

There are only 10 types of people in this world...
those who understand binary, and those who don't.

-------------- next part --------------
#!/usr/bin/perl -w
use strict;
use IO::Socket;

# Define the hostnames to update at zoneedit
my @hostnames = ( "mydomain.com",
		"mail.mydomain.com",
		"myotherdomain.com",
		"mail.myotherdomain.com",
		"www.myotherdomain.com",
		);
# zoneedit username
my $username = "Username1";
# zoneedit password for above username
my $password = "p455w0rd";
# location of the wget binary
my $wget = "/usr/bin/wget";
# location of the file you would like to store the router's public IP address in
my $router_ip_config = "/etc/router_pub_ip";

# password for the linksys, to do a screenscrape and grab the
# current IP.  Set linksys_in_use to 0 if you don't have one.
my $linksys_in_use = 1;
my $linksys_pw = "p455w0rd";
# we assume that the default GW is the linksys.
# if this is incorrect, set it here:
my $linksys_ip = "";

# get the linksys's current external IP address.
my $router_cur_ip;
if ($linksys_in_use) {
	$router_cur_ip = &linksys_scrape($linksys_pw, $linksys_ip);
} else { 
	# If you're not using a linksys, write your own function
	# here to retrieve the IP address of your external connection
	$router_cur_ip = 0; 
}	

# compare the linksys's current public IP with what we wrote down
# last time.
if ( -f $router_ip_config) {
	require $router_ip_config;
}

# if they're different, update the file containing the router's
# public IP and then update zoneedit.
if ($router_cur_ip ne $Config::router_pub_ip) { 
	&update_router_pub_ip($router_cur_ip);
	&update_zoneedit(\@hostnames);
}

# Linksys scrape sub.  This pulls the linksys's public IP address out of 
# the status page.  This may need some tuning for firmware versions other
# than 1.42.7
# Call this with linksys_scrape(linksys_pw, linksys_ip).  If your default
# gw is the linksys, no need for linksys_ip.
sub linksys_scrape {
	my $linksys_pw = shift;
	my $linksys_ip = shift;
	($linksys_ip = &get_default_gw) unless $linksys_ip;
	my $data = `$wget -O - --http-user=x --http-passwd=$linksys_pw 'http://$linksys_ip/Status.htm' 2>/dev/null`;
	$data =~ s/.*IP Address:<\/td><td><font face=verdana size=2>//;
	$data =~ s/<.*//;
	return $data;
}

# sub to get the default gateway.  relies on netstat.
sub get_default_gw {
	# get the output of netstat
	my @route_info_lines = split(/\n/, `netstat -rn`);
	# grab the last line (where the default gw hangs out)
	my $lastline = $route_info_lines[(scalar(@route_info_lines) - 1)];
	# split the line into fields and take the second field.
	my $defgw = (split(/\s+/, $lastline))[1];
	# return the default gw
	return $defgw;
}

# sub to update the config file that we store the default router IP
# address in.
sub update_router_pub_ip {
	my $new_ip = shift;
	# open (and clobber the old) file for writing
	open (RTRPUB, "+>$router_ip_config");
	print RTRPUB "# This file contains your router (linksys, linux, whatever)'s\n",
			"# public IP Address.  This is used by the dynamic updating program\n",
			"# you use to update zoneedit.  Please do not edit this file unless\n",
			"# you're sure that you know what you're doing.\n",
			"package Config;\n",
			"\$router_pub_ip = \"$new_ip\";\n",
			"# Old Router pub IP: $Config::router_pub_ip\n",
			"1;";
	close RTRPUB;
}

sub update_zoneedit {
	my $hostsref = shift;
	my @hosts = @$hostsref;
	# iterate over the hosts we defined at the top, updating each
	# with zoneedit's dynamic updating page.  As we update each, 
	# print a message saying so.  This will allow cron to mail
	# the results of changes to root.
	foreach my $host (@hosts) {
		system("$wget -O /dev/null --http-user=$username --http-passwd=$password 'http://dynamic.zoneedit.com/auth/dynamic.html?host=$host' 2>/dev/null");
		print "$host updated to new IP: $router_cur_ip\n";
	}
}