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#
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# control-services.pl -- Monitor a listed set of services to be sure
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# they are running. If not running, modify the DNS system
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# to remove them from the lookup for that service
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#
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# '$RCSfile$'
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# Copyright: 2005 Regents of the University of California
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#
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# '$Author: jones $'
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# '$Date: 2005-10-13 15:43:22 -0700 (Thu, 13 Oct 2005) $'
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# '$Revision: 2674 $'
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#
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 2 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program; if not, write to the Free Software
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# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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#
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Welcome to the control-services.pl program.
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This program is designed to run as a script under the Hobbit system monitoring
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program (http://hobbitmon.sourceforge.net/). When Hobbit is configured
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properly, this script will be called to make changes to the DNS services that
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are registered in your DNS server. The changes are accomplished using
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Dynamic DNS (DDNS). The system is intended to help manage a set of services
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that are running on several hosts in round-robin DNS fashion and to remove
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inaccessible hosts when they are detected as failed, and restore them when
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they recover.
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Configuration consists of:
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1) Install and configure Hobbit (see http://hobbitmon.sourceforge.net)
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2) Install and configure BIND for DDNS (see below)
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3) Install this script (see below)
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3) Setting up BIND for DDNS
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-----------------------------
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You need to configure BIND to accept signed dynamic updates for your zone.
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a) Create a key using dnssec-keygen.
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% dnssec-keygen -b 256 -n HOST -a HMAC-MD5 example
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This will create 2 key files in different formats
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b) Add the key to your named.conf file in a block (copy it from either
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of the two generated key files):
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key "examplekey" {
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algorithm hmac-md5;
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secret "0QI/OEYtZA5aI6rpMTwrodfMpg1xxCaDHdR/tvI9Lgc=";
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};
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c) For each zone that you want to enable updates, add this key to
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your 'allow-update' and 'allow-transfer' blocks:
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zone "example.com" {
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type master;
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file "/var/named/example.com.zone"
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allow-update ( key examplekey; };
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allow-transfer { key examplekey; };
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}
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d) Reload named to reload your configuration (killall -HUP named).
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3) Install the control-services.pl script
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-----------------------------------------
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Prerequisites:
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The following Perl Modules are required:
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Net::DNS
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LWP::UserAgent
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HTTP::Request
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HTTP::Response
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URI::URL
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These modules are available through CPAN, and are most easily gotten using
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the CPAN shell (as root, "perl -MCPAN -e shell").
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Installation:
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1) copy the file to a commonly accessible location (typically /usr/local/bin)
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2) change ownership to the web-server user
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3) copy the configuration file to /etc and customize for your situation
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-- set the key name and value from your DDNS server
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-- set domain and other parameters properly
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4) change ownership of the config file to the web-server user
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5) restrict access to the config file to only the web server user
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6) Create the log file directory, writable by the hobbit user
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7) Place alert rules in the hobbit/server/etc/hobbit-alerts.cfg file that
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use the script. See the hobbit-alerts.cfg man page for details. An
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example rule might be:
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HOST=ldap.example.com SERVICE=ldap RECOVERED
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SCRIPT /usr/local/bin/control-services.pl ldap FORMAT=SCRIPT REPEAT=1
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IMPORTANT NOTE
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----------------
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Make sure that the configuration file is only readable by the webserver user
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and writable by root. The config file contains the key to allow updates
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to your DNS server, so be sure the config file is secure.
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Enjoy!
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