DNS monitor

Had a little incident today, so I ended up writing this.

Uses 'nslookup' because I actually wanted some of the nslookup side-effects;for example, it's difficult to get 'host' to "show it's work" and yetalso producethe same output in the same order each time (so the 'diff' will work correctly). Crude, yet effective.

Hopefully It'll just run quietly for years, never kicking off emails from cron,but at least now I won't be blindsided when somebody decides that simplybecause you can't ping something, it's okay to delete the host from DNS ;)

$ cat  $HOME/bin/dns-validate.pl



#! /usr/bin/perl



#



# No authorship, no copyright, no support.



# KK2005



#



#



$nslookup="/usr/sbin/nslookup";







$dir=$ENV{'HOME'}."/public_html/dns/";







$oldfile=$dir."status.then";



$outfile=$dir."status.now";







@ns= (  "127.0.0.1","207.227.240.1",



      );



#



#



#



die "Missing nslookup $nslookup $!"  unless(-x $nslookup);







chdir($dir)  die $!;



rename($outfile,$oldfile);







system("co -q -l $outfile");



open(OUT,">$outfile")  die $!;







while() {



      next if(m/^#/);



      chomp;



      print OUT "#" x 64, "\n";



      print OUT "#\n# ",$_,"#\n\n";







      foreach $server (sort(@ns)) {



              print OUT "\n # Server $server\n";



              print OUT `nslookup $_ $server`;



              print OUT "\n";



              }



      print OUT "### End $_ $nameserver###\n";



      }



print OUT "\n###\n# End nslookup\n#\n";











print OUT "\n# Contents of /etc/resolv.conf\n",`cat /etc/resolv.conf`,"\n";



print OUT "###EOF###\n";







close(OUT);



chmod(0644,$outfile);







system("ci", "-u", "-q", "-m$0", $outfile);



system("diff", "-w", "-c", "-T", $oldfile, $outfile);



exit($?);











__DATA__



#



#



# Enter your hostnames here, one per line.



# Comment lines must have a '#' as the very first character



#



# Example entries below, I recommend removing these.



#



127.0.0.1



example.com



###EOF###