Category:	Networking Code
Author/Contact Info	ybiC
Description:	One of my boxen is dial-connected nailed up using /etc/ppp/ppp_on_boot plus persist and holdoff parameters in /etc/ppp/peers/provider.   Whenever the connection is (re)established, this ditty sends the new ppp0 IP address to my dynamic DNS provider. Not much of a Perlish exercise, but was fun to make practical use of new (to me anyways) IO::Interface. Start dynamic DNS update: Check ppp0 status: ACTIVE Query host for ppp0 address: PASS Post ppp0 IP address to DynDNS service: PASS Check DNS propagation via name lookup: PASS Compare resolved address to local: PASS nnn.nnn.nnn.nnn <= my.host.com nnn.nnn.nnn.nnn <= ppp0 Finished dynamic DNS update
#!/usr/bin/perl -w # ddns.pl # pod at tail $|++; use strict; use IO::Socket; use IO::Interface; use HTTP::Request::Common qw(POST); use LWP::UserAgent; my $id = ''; my $pass = ''; my $site = ''; my $fqdn = ''; my $if = 'ppp0'; print "\n"; print "Start dynamic DNS update for $fqdn:\n"; print "\n"; my $s = IO::Socket::INET->new(Proto => 'udp'); my @interfaces = $s->if_list; print "Check $if status: "; my $ifup = 0; for(@interfaces){ $ifup++ if( $_ =~/$if/ ); } if($ifup == 0){ print "INACTIVE - ABORT\n\n"; exit 0; } print "ACTIVE\n"; print "Query host for $if address: "; my $addr; if($addr = $s->if_addr($if)) { print "PASS\n"; } else { print "FAIL:\n$!"; } print "Post $if IP address to DynDNS service: "; my $ua = LWP::UserAgent->new(); $ua->credentials($id, $pass); my $request = POST "$site", [ip => $addr, action => 'update']; $request->authorization_basic($id, $pass); my $response = $ua->request($request); if ($response->is_success) { print "PASS\n"; } else { print "FAIL:\n", $response-> message, "\n"; exit 0; } print "Check DNS propagation via name lookup: "; my $packed_address = gethostbyname($fqdn); unless ($packed_address) { print "FAIL:\n $!"; exit 0; } print "PASS\n"; print "Compare resolved address to local: "; my $dotted_quad = inet_ntoa($packed_address); if($dotted_quad eq $addr){ print "PASS\n"; } else { print "FAIL:\n$!"; exit 0; } print " $dotted_quad <= $fqdn\n"; print " $addr <= $if\n"; print "\n"; print "Finished dynamic DNS update for $fqdn:\n\n"; exit 1; ###################################################################### +##### =head1 NAME ddns.pl =head1 DESCRIPTION Update dynamicDNS service for computer on dial-up connection. =head1 USAGE Accepts no arguments. Create symlink in /etc/ppp/ip-up.d/ so will be called whenever dial-up connection is (re)establised: ln -isv /path/to/ddns.pl /etc/ip-up.d/ddns Works well in conjuntion with /etc/ppp/peers/provider 'persist' and 'holdoff' parameters plus /etc/ppp/ppp_on_boot for nailed-up connecti +on. =head1 REQUIREMENTS perl 5 libwww-perl IO::Interface make to install modules gcc " " " libc6-dev " " /etc/nsswitch => hosts: dns files so name confirm is from DNS not /etc/hosts. =head1 UPDATE November 27, 2001 20:20 CST Compare local interface IP address with DNS lookup address. Check for interface active before proceeding. Confirm DNS updated correct IP address with gethostbyname(). Use IO::Socket+Interface to determine local ppp0 IP address instead of ifconfig with backticks. Eliminate (unecessary) subroutines. October 27, 1999 Initial working code. =head1 CREDITS jwest for nsswitch, libc6-dev tips vroom for PerlMonks =head1 AUTHOR ybiC =cut