185 lines
3.8 KiB
Perl
Executable File
185 lines
3.8 KiB
Perl
Executable File
#!/usr/bin/perl -w
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=head1 NAME
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dnsresponse - Plugin to monitor DNS resolution times.
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"Poor man's smokeping" :)
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=head1 APPLICABLE SYSTEMS
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Any unix system.
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=head1 CONFIGURATION
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The following shows the default configuration.
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[dnsresponse_*]
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env.site www.google.com
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env.times 20
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=head1 INTERPRETATION
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The plugin shows the average and median times taken to resolve a site.
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=head1 MAGIC MARKERS
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#%# family=auto
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#%# capabilities=autoconf,suggest
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=head1 BUGS
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None known.
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=head1 VERSION
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$Id: dnsresponse_ 61 2009-04-14 09:11:00Z stsimb $
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=head1 AUTHOR
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Copyright (c) 2009 by Sotiris Tsimbonis.
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=head1 LICENSE
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GPLv2
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=cut
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#%# family=auto
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#%# capabilities=autoconf suggest
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use strict;
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use warnings;
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my $DEBUG=0;
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my $site = exists $ENV{'site'} ? $ENV{'site'} : "www.google.com";
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my $times = exists $ENV{'times'} ? $ENV{'times'} : "20";
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my $resconf="/etc/resolv.conf";
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use File::Basename;
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my $basename=basename($0);
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my $scriptname;
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my $dnsip;
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($scriptname, $dnsip) = split("_", $basename);
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print "DBG: target dns ip $dnsip\n" if ($DEBUG>0);
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if ( defined $ARGV[0] and $ARGV[0] eq "config" ) {
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print "graph_title $dnsip DNS response time\n";
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print "graph_vlabel milliseconds\n";
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print "graph_scale no\n";
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print "graph_category dns\n";
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print "graph_info Time taken by $dnsip to resolve $site $times times.\n";
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#my @val = ("min", "avg", "median", "max");
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my @val = ("avg", "median", "stddev");
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my $value;
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foreach $value ( @val ) {
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if ($value eq "stddev") {
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print "$value.info Standard deviation (variance).\n";
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} else {
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print "$value.info $value time taken by $dnsip to resolve $site $times times.\n";
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}
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print "$value.label $value\n";
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# print "$value.type DERIVE\n";
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# print "$value.min 0\n";
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# print "$value.warning 100\n";
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# print "$value.critical 600\n";
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}
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exit 0;
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}
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if ( defined $ARGV[0] and $ARGV[0] eq "autoconf" ) {
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my $ret;
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if (! eval "require Net::DNS;") { $ret .= "Net::DNS not found. "; }
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if (! eval "require Time::HiRes;") { $ret .= "Time::HiRes not found. "; }
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if (! -s $resconf) { $ret .= "$resconf not found. "; }
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if ($ret) {
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print "no ($ret)\n";
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} else {
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print "yes\n";
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}
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exit 0;
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}
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if ( defined $ARGV[0] and $ARGV[0] eq "suggest" ) {
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if (-s $resconf) {
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open (FILE, "< $resconf") || die "Could not open $resconf: $!\n";
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my $line;
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while ($line = <FILE>) {
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if ($line =~ /^nameserver/) {
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my $ns; my $ip;
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($ns, $ip) = split(" ", $line);
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print "$ip\n";
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}
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}
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exit 0;
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} else {
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print "ERROR reading $resconf\n";
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exit 1;
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}
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}
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use Time::HiRes qw ( gettimeofday tv_interval );
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use Net::DNS;
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my $res = Net::DNS::Resolver->new(
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nameservers => [$dnsip],
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recurse => 1,
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debug => $DEBUG,
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);
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my $i;
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my @restimes;
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for ($i=1; $i<=$times; $i++) {
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my $t0 = [gettimeofday];
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my $answer = $res->send($site);
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my $elapsed = tv_interval ($t0);
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push(@restimes, $elapsed);
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print "DBG: count $i elapsed $elapsed\n" if ($DEBUG>0);
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}
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@restimes=sort(@restimes);
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#my $min=$restimes[0]*1000;
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my $average=mean(@restimes)*1000;
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my $median=median(@restimes)*1000;
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my $stddev=std_dev_ref_sum(@restimes)*1000;
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#my $max=$restimes[$times-1]*1000;
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#print "min.value $min\n";
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print "avg.value $average\n";
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print "median.value $median\n";
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print "stddev.value $stddev\n";
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#print "max.value $max\n";
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sub mean {
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my $result;
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foreach (@_) { $result += $_ }
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return $result / @_;
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}
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sub median {
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my @ar = @_;
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my $elements = scalar(@ar);
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return $ar[(int($elements-1)/2)];
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# if ($elements % 2) {
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# return $ar[($elements-1)/2];
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# } else {
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# return ($ar[($elements-1)/2-0.5]+$ar[($elements-1)/2+0.5])/2;
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# }
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}
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# Standard Deviance function from http://www.linuxjournal.com/article/6540
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sub std_dev_ref_sum {
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my @ar = @_;
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my $elements = scalar @ar;
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my $sum = 0;
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my $sumsq = 0;
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foreach (@ar) {
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$sum += $_;
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$sumsq += ($_ **2);
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}
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return sqrt( $sumsq/$elements - (($sum/$elements) ** 2));
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}
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