| 1 | #! /usr/bin/perl
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| 2 | # --------------------------------------------------------------------
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| 3 | # Copyright (C) 2006 Oliver Hitz <oliver@net-track.ch>
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| 4 | #
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| 5 | # $Id: dhcpd-snmp.in,v 1.2 2006/01/25 19:26:00 oli Exp $
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| 6 | #
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| 7 | # This program is free software; you can redistribute it and/or modify
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| 8 | # it under the terms of the GNU General Public License as published by
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| 9 | # the Free Software Foundation; either version 2 of the License, or
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| 10 | # (at your option) any later version.
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| 11 | #
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| 12 | # This program is distributed in the hope that it will be useful, but
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| 13 | # WITHOUT ANY WARRANTY; without even the implied warranty of
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| 14 | # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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| 15 | # General Public License for more details.
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| 16 | #
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| 17 | # You should have received a copy of the GNU General Public License
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| 18 | # along with this program; if not, write to the Free Software
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| 19 | # Foundation, Inc., 59 Temple Place - Suite 330, Boston,
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| 20 | # MA 02111-1307, USA.
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| 21 | # --------------------------------------------------------------------
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| 22 | # dhcpd-snmp
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| 23 | #
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| 24 | # An extension for polling the active and available lease counts of a
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| 25 | # running dhcpd.
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| 26 | #
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| 27 | # Please read the man page dhcpd-snmp(8) for instructions.
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| 28 | # --------------------------------------------------------------------
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| 29 |
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| 30 | use Time::Local;
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| 31 | use strict;
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| 32 |
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| 33 | # The base OID of this extension. Has to match the OID in snmpd.conf:
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| 34 | my $baseoid = ".1.3.6.1.4.1.21695.1.2";
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| 35 |
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| 36 | # Results are cached for some seconds so that an SNMP walk doesn't
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| 37 | # result in dhcpd.leases being parsed multiple times.
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| 38 | my $cache_secs = 60;
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| 39 |
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| 40 | # --------------------------------------------------------------------
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| 41 |
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| 42 | my $mib;
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| 43 | my $mibtime;
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| 44 |
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| 45 | # Load configuration file
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| 46 | my $conf = read_configuration($ARGV[0]);
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| 47 |
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| 48 | # Switch on autoflush
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| 49 | $| = 1;
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| 50 |
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| 51 | # Main loop
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| 52 | while (my $cmd = <STDIN>) {
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| 53 | chomp $cmd;
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| 54 |
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| 55 | if ($cmd eq "PING") {
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| 56 | print "PONG\n";
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| 57 | } elsif ($cmd eq "get") {
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| 58 | my $oid_in = <STDIN>;
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| 59 |
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| 60 | my $oid = get_oid($oid_in);
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| 61 | my $mib = create_dhcp_mib();
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| 62 |
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| 63 | if ($oid != 0 && defined($mib->{$oid})) {
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| 64 | print "$baseoid.$oid\n";
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| 65 | print $mib->{$oid}[0]."\n";
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| 66 | print $mib->{$oid}[1]."\n";
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| 67 | } else {
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| 68 | print "NONE\n";
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| 69 | }
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| 70 | } elsif ($cmd eq "getnext") {
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| 71 | my $oid_in = <STDIN>;
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| 72 |
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| 73 | my $oid = get_oid($oid_in);
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| 74 | my $found = 0;
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| 75 |
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| 76 | my $mib = create_dhcp_mib();
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| 77 | my @s = sort { oidcmp($a, $b) } keys %{ $mib };
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| 78 | for (my $i = 0; $i < @s; $i++) {
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| 79 | if (oidcmp($oid, $s[$i]) == -1) {
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| 80 | print "$baseoid.".$s[$i]."\n";
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| 81 | print $mib->{$s[$i]}[0]."\n";
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| 82 | print $mib->{$s[$i]}[1]."\n";
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| 83 | $found = 1;
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| 84 | last;
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| 85 | }
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| 86 | }
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| 87 | if (!$found) {
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| 88 | print "NONE\n";
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| 89 | }
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| 90 | } else {
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| 91 | # Unknown command
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| 92 | }
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| 93 | }
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| 94 |
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| 95 | exit 0;
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| 96 |
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| 97 | sub get_oid
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| 98 | {
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| 99 |
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| 100 | my ($oid) = @_;
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| 101 | chomp $oid;
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| 102 |
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| 103 | my $base = $baseoid;
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| 104 | $base =~ s/\./\\./g;
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| 105 |
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| 106 | if ($oid !~ /^$base(\.|$)/) {
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| 107 | # Requested oid doesn't match base oid
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| 108 | return 0;
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| 109 | }
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| 110 |
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| 111 | $oid =~ s/^$base\.?//;
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| 112 | return $oid;
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| 113 | }
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| 114 |
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| 115 | sub oidcmp {
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| 116 | my ($x, $y) = @_;
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| 117 |
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| 118 | my @a = split /\./, $x;
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| 119 | my @b = split /\./, $y;
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| 120 |
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| 121 | my $i = 0;
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| 122 |
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| 123 | while (1) {
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| 124 |
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| 125 | if ($i > $#a) {
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| 126 | if ($i > $#b) {
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| 127 | return 0;
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| 128 | } else {
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| 129 | return -1;
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| 130 | }
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| 131 | } elsif ($i > $#b) {
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| 132 | return 1;
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| 133 | }
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| 134 |
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| 135 | if ($a[$i] < $b[$i]) {
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| 136 | return -1;
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| 137 | } elsif ($a[$i] > $b[$i]) {
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| 138 | return 1;
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| 139 | }
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| 140 |
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| 141 | $i++;
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| 142 | }
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| 143 | }
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| 144 |
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| 145 | sub create_dhcp_mib
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| 146 | {
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| 147 | # We cache the results for $cache_secs seconds
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| 148 | if (time - $mibtime < $cache_secs) {
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| 149 | return $mib;
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| 150 | }
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| 151 |
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| 152 | # Read in all leases
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| 153 | read_leases();
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| 154 |
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| 155 | my %dhcp = (
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| 156 | "1" => [ "integer", 0 ], # Number of pools
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| 157 | );
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| 158 |
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| 159 | foreach my $i (keys %{ $conf->{"pools"} }) {
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| 160 | $dhcp{"1"}[1]++;
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| 161 |
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| 162 | my $pool = $conf->{"pools"}->{$i};
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| 163 |
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| 164 | $dhcp{"2.1.".$i} = [ "integer", $i ];
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| 165 | $dhcp{"2.2.".$i} = [ "string", $pool->{"name"} ];
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| 166 | $dhcp{"2.3.".$i} = [ "integer", $pool->{"total"} ];
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| 167 | $dhcp{"2.4.".$i} = [ "integer", $pool->{"active"} ];
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| 168 | $dhcp{"2.5.".$i} = [ "integer", $pool->{"expired"} ];
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| 169 | $dhcp{"2.6.".$i} = [ "integer", $pool->{"total"} - $pool->{"active"} ];
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| 170 | }
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| 171 |
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| 172 | $mib = \%dhcp;
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| 173 | $mibtime = time;
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| 174 | return $mib;
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| 175 | }
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| 176 |
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| 177 | sub ip2int {
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| 178 | my ($ip) = @_;
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| 179 |
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| 180 | if ($ip =~ /^(\d{1,3})\.(\d{1,3})\.(\d{1,3})\.(\d{1,3})$/) {
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| 181 | return 256*(256*(256*$1+$2)+$3)+$4;
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| 182 | } else {
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| 183 | return -1;
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| 184 | }
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| 185 | }
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| 186 |
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| 187 | sub read_leases
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| 188 | {
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| 189 | # Clear leases
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| 190 | foreach my $i (keys %{ $conf->{"pools"} }) {
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| 191 | $conf->{"pools"}->{$i}->{"leases"} = ();
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| 192 | $conf->{"pools"}->{$i}->{"active"} = 0;
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| 193 | $conf->{"pools"}->{$i}->{"expired"} = 0;
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| 194 | }
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| 195 |
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| 196 | # Read leases
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| 197 | if (!open(LEASES, $conf->{"leases"})) {
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| 198 | printf STDERR "Unable to open leases file '%s'!\n", $conf->{leases};
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| 199 | return;
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| 200 | }
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| 201 |
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| 202 | my %l = undef;
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| 203 |
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| 204 | while (my $line = <LEASES>) {
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| 205 | if ($line =~ /^lease (\d+\.\d+\.\d+\.\d+) \{$/) {
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| 206 | my $ip = ip2int($1);
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| 207 | undef %l;
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| 208 |
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| 209 | foreach my $i (keys %{ $conf->{"pools"} }) {
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| 210 | my $pool = $conf->{"pools"}->{$i};
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| 211 | my $found = 0;
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| 212 |
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| 213 | foreach my $r (@{ $pool->{"ranges"} }) {
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| 214 | if (($ip >= $r->{"from"}) && ($ip <= $r->{"to"})) {
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| 215 | %l = ( "pool" => $i, "ip" => $ip );
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| 216 | $found = 1;
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| 217 | last;
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| 218 | }
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| 219 | }
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| 220 | if ($found) {
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| 221 | last;
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| 222 | }
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| 223 | }
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| 224 | } elsif (defined %l && $line =~ /^\s+ends \d (\d+)\/(\d+)\/(\d+) (\d+):(\d+):(\d+);$/) {
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| 225 | $l{"ends"} = timegm($6, $5, $4, $3, $2-1, $1);
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| 226 | } elsif (defined %l && $line =~ /^\s+ends never;$/) {
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| 227 | $l{"ends"} = -1;
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| 228 | } elsif (defined %l && $line =~ /^\}$/) {
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| 229 | $conf->{"pools"}->{$l{"pool"}}->{"leases"}->{$l{"ip"}} = $l{"ends"};
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| 230 | }
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| 231 | }
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| 232 |
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| 233 | close(LEASES);
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| 234 |
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| 235 | # Count active and expired leases
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| 236 | my $now = time();
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| 237 |
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| 238 | foreach my $i (keys %{ $conf->{"pools"} }) {
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| 239 | my $pool = $conf->{"pools"}->{$i};
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| 240 |
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| 241 | foreach my $ip (keys %{ $pool->{"leases"} }) {
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| 242 | my $end = $pool->{"leases"}->{$ip};
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| 243 | if (($end == -1) || ($end >= $now)) {
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| 244 | $pool->{"active"}++;
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| 245 | } else {
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| 246 | $pool->{"expired"}++;
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| 247 | }
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| 248 | }
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| 249 | }
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| 250 | }
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| 251 |
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| 252 | sub read_configuration
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| 253 | {
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| 254 | my ($f) = @_;
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| 255 |
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| 256 | my %conf = ( "leases" => undef,
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| 257 | "pools" => { } );
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| 258 |
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| 259 | open C, "$f";
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| 260 | while (my $l = <C>) {
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| 261 | $l =~ s/#.*//;
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| 262 | $l =~ s/^\s*//;
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| 263 | $l =~ s/\s*$//;
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| 264 |
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| 265 | if ($l eq "") {
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| 266 | next;
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| 267 | }
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| 268 |
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| 269 | if ($l =~ /^leases:\s*(\S+)$/) {
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| 270 |
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| 271 | $conf{"leases"} = $1;
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| 272 |
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| 273 | # Check if file is readable
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| 274 | if (open(LEASES, $conf{"leases"})) {
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| 275 | close(LEASES);
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| 276 | } else {
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| 277 | printf STDERR "Unable to open leases file '%s'!\n", $conf{"leases"};
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| 278 | }
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| 279 |
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| 280 | } elsif ($l =~ /^pool:\s*(\d+)\s*,\s*("[^"]*"|[^"][^,]*)\s*,\s*(.*)$/) {
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| 281 |
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| 282 | # Read the pool definition
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| 283 | my %p = ( "index" => $1,
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| 284 | "name" => $2,
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| 285 | "ranges" => [ ],
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| 286 | "total" => 0,
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| 287 | "leases" => { } );
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| 288 |
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| 289 | my @ranges = split /\s*,\s*/, $3;
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| 290 |
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| 291 | $p{"name"} =~ s/^\"//;
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| 292 | $p{"name"} =~ s/\"$//;
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| 293 |
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| 294 | foreach my $r (@ranges) {
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| 295 | if ($r !~ /^(\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3})-(\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3})$/) {
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| 296 | printf STDERR "Invalid range definition '%s'.\n", $r;
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| 297 | next;
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| 298 | }
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| 299 |
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| 300 | my ($from, $to) = ($1, $2);
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| 301 |
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| 302 | my $fromip = ip2int($from);
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| 303 | my $toip = ip2int($to);
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| 304 |
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| 305 | if ($toip < $fromip) {
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| 306 | my $t = $toip;
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| 307 | $toip = $fromip;
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| 308 | $fromip = $t;
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| 309 | }
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| 310 |
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| 311 | $p{"total"} += $toip-$fromip+1;
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| 312 |
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| 313 | my %range = ( "from" => $fromip,
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| 314 | "to" => $toip );
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| 315 |
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| 316 | push @{ $p{"ranges"} }, \%range;
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| 317 | }
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| 318 |
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| 319 | $conf{"pools"}{$p{"index"}} = \%p;
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| 320 | } else {
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| 321 |
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| 322 | printf STDERR "Invalid line '%s'.\n", $l;
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| 323 |
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| 324 | }
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| 325 | }
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| 326 |
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| 327 | return \%conf;
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| 328 | }
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| 329 |
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| 330 | __END__
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| 331 |
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| 332 | =head1 NAME
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| 333 |
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| 334 | dhcpd-snmp
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| 335 |
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| 336 | =head1 SYNOPSIS
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| 337 |
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| 338 | dhcpd-snmp dhcpd-snmp.conf
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| 339 |
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| 340 | =head1 DESCRIPTION
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| 341 |
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| 342 | B<dhcpd-snmp> is an extension for the Net-SNMP agent and the ISC DHCP
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| 343 | server. It allows you to monitor and track the address usage of your
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| 344 | dynamic IP address pools through SNMP.
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| 345 |
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| 346 | =head1 CONFIGURATION FILE
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| 347 |
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| 348 | The configuration file defines the location of the F<dhcpd.leases>
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| 349 | file as well as the pools of which you want to access the lease
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| 350 | counts.
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| 351 |
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| 352 | The file is in B<key: value> format and allows only two keys:
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| 353 |
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| 354 | =over 8
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| 355 |
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| 356 | =item B<leases>: C</var/lib/dhcp3/dhcpd.leases>
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| 357 |
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| 358 | Location of the F<dhcpd.leases> file. This file needs to be accessible
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| 359 | by the script.
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| 360 |
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| 361 | =item B<pool>: C<index>, C<description>, C<ip1-ip2, ip3-ip4...>
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| 362 |
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| 363 | Defines a pool to monitor. C<index> is a unique numeric index,
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| 364 | C<description> a textual description of this pool, and C<ip1-ip2,
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| 365 | ip3-ip4, ...> defines the ranges of IP addresses belonging to this
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| 366 | pool.
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| 367 |
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| 368 | =back
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| 369 |
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| 370 | Since this extension is a persistent script, changes to the
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| 371 | configuration file require a restart of snmpd.
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| 372 |
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| 373 | =head1 INSTALLATION
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| 374 |
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| 375 | After installing the B<dhcpd-snmp> script and adapting the
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| 376 | configuration file, it is best to test it manually. This can be done
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| 377 | with the following dialog:
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| 378 |
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| 379 | PING
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| 380 |
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| 381 | The script should return "PONG".
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| 382 |
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| 383 | get
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| 384 | .1.3.6.1.4.1.21695.1.2.1
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| 385 |
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| 386 | The script should return three lines: the OID, "integer", and the
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| 387 | number of configured pools.
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| 388 |
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| 389 | get
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| 390 | .1.3.6.1.4.1.21695.1.2.2.2.1
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| 391 |
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| 392 | OID, "string", and the name of your first address pool.
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| 393 |
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| 394 | get
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| 395 | .1.3.6.1.4.1.21695.1.2.2.4.1
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| 396 |
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| 397 | OID, "integer", and the number of active leases.
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| 398 |
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| 399 | Quit the dialog using CTRL-D.
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| 400 |
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| 401 | If everything works, insert the following line into your Net-SNMP's
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| 402 | B<snmpd.conf> configuration file:
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| 403 |
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| 404 | pass_persist .1.3.6.1.4.1.21695.1.2 path/to/dhcpd-snmp path/to/dhcpd-snmp.conf
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| 405 |
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| 406 | Net-SNMP will need to be restarted after this change.
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| 407 |
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| 408 | You should now be able to get the statistics using F<snmpwalk>, for example:
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| 409 |
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| 410 | $ snmpwalk host community .1.3.6.1.4.1.21695.1.2
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| 411 |
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| 412 | This should give you a list of the statistics of your DHCP server.
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| 413 |
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| 414 | =head1 MIB
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| 415 |
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| 416 | The script returns the following variables:
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| 417 |
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| 418 | .1.3.6.1.4.1.21695.1.2.1: number of configured pools
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| 419 | .1.3.6.1.4.1.21695.1.2.2.<pool>: pool description
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| 420 | .1.3.6.1.4.1.21695.1.2.3.<pool>: size of the pool (number of addresses)
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| 421 | .1.3.6.1.4.1.21695.1.2.4.<pool>: active leases
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| 422 | .1.3.6.1.4.1.21695.1.2.5.<pool>: expired leases
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| 423 | .1.3.6.1.4.1.21695.1.2.6.<pool>: available addresses (size - active leases)
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| 424 |
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| 425 | For a complete MIB file see the C<mibs> directory in the source archive.
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| 426 |
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| 427 | =head1 SECURITY
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| 428 |
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| 429 | It is assumed that users of this script know how to properly secure
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| 430 | their snmpd. Please read the corresponding man pages on more
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| 431 | information about this.
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| 432 |
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| 433 | =head1 COPYRIGHT AND LICENSE
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| 434 |
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| 435 | Copyright (C) 2006 Oliver Hitz
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| 436 |
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| 437 | This program is free software; you can redistribute it and/or modify
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| 438 | it under the terms of the GNU General Public License as published by
|
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| 439 | the Free Software Foundation; either version 2 of the License, or (at
|
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| 440 | your option) any later version.
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| 441 |
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| 442 | This program is distributed in the hope that it will be useful, but
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| 443 | WITHOUT ANY WARRANTY; without even the implied warranty of
|
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| 444 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
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| 445 | General Public License for more details.
|
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| 446 |
|
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| 447 | You should have received a copy of the GNU General Public License
|
|---|
| 448 | along with this program; if not, write to the Free Software
|
|---|
| 449 | Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
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| 450 | USA.
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| 451 |
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| 452 | =cut
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