In this tutorial I will describe how to install and configure MyDNS and MyDNSConfig on CentOS 5.1. MyDNS is a DNS server that uses a MySQL database as backend instead of configuration files like, for example, Bind or djbdns. The advantage is that MyDNS simply reads the records from the database, and it does not have to be restarted/reloaded when DNS records change or zones are created/edited/deleted. A secondary nameserver can be easily set up by installing a second instance of MyDNS that accesses the same database or, to be more redundant, uses the MySQL master / slave replication features to replicate the data to the secondary nameserver.
MyDNSConfig is an easy to use web-based interface to MyDNS. MyDNSConfig can create all types of DNS records that are available in MyDNS and adds features like user management and access privileges.
I do not issue any guarantee that this will work for you!
1 Preliminary Note
In this tutorial I use the hostname server1.example.com with the IP address 192.168.0.100. These settings might differ for you, so you have to replace them where appropriate.
2 Installing The Prerequisites
First we enable the RPMforge repository on our CentOS system as some of the packages that we are going to install in the course of this tutorial are not available in the official CentOS 5.1 repositories:
rpm -Uhv http://apt.sw.be/packages/rpmforge-release/rpmforge-release-0.3.6-1.el5.rf.i386.rpm
MyDNSConfig is a web-based interface to MyDNS written in PHP. This requires a webserver with PHP enabled and the MySQL database server. If you have already Apache, PHP and MySQL installed, you may skip this step. We also install phpMyAdmin here so that you have a web interface to the MySQL database in case you need it:
yum install httpd mysql-server php php-mysql php-mbstring phpmyadmin
chkconfig –levels 235 mysqld on
Then set passwords for the MySQL root account:
mysqladmin -u root password yourrootsqlpassword
mysqladmin -h server1.example.com -u root password yourrootsqlpassword
Now we configure phpMyAdmin. We change the Apache configuration so that phpMyAdmin allows connections not just from localhost (by commenting out the <Directory “/usr/share/phpmyadmin”> stanza):
# # Web application to manage MySQL # #<Directory "/usr/share/phpmyadmin"> # Order Deny,Allow # Deny from all # Allow from 127.0.0.1 #</Directory> Alias /phpmyadmin /usr/share/phpmyadmin Alias /phpMyAdmin /usr/share/phpmyadmin Alias /mysqladmin /usr/share/phpmyadmin
Next we change the authentication in phpMyAdmin from cookie to http:
[...] /* Authentication type */ $cfg['Servers'][$i]['auth_type'] = 'http'; [...]
Then we create the system startup links for Apache and start it:
chkconfig –levels 235 httpd on
Now you can direct your browser to http://server1.example.com/phpmyadmin/ or http://192.168.0.100/phpmyadmin/ and log in with the user name root and your new root MySQL password.
3 Installing MyDNSConfig
Log in to MySQL and create the database:
mysql -u root -p
CREATE DATABASE mydns;
GRANT SELECT, INSERT, UPDATE, DELETE ON mydns.* TO ‘mydns’@’localhost’ IDENTIFIED BY ‘mydnspassword’;
GRANT SELECT, INSERT, UPDATE, DELETE ON mydns.* TO ‘mydns’@’localhost.localdomain’ IDENTIFIED BY ‘mydnspassword’;
Replace the word mydnspassword in the above commands with a password of your choice.
tar xvfz MyDNSConfig-1.1.0.tar.gz
cp -rf interface/* /usr/share/mydnsconfig/
ln -s /usr/share/mydnsconfig/web/ /var/www/html/mydnsconfig
Install the MyDNSConfig MySQL Database:
mysql -u root -p mydns < install/mydnsconfig.sql
The command above asks for a password, please enter the password of the MySQL root user.
Edit the MyDNSConfig configuration; please make sure you fill in the correct database settings:
<?php /* Copyright (c) 2005, Till Brehm, Falko Timme, projektfarm Gmbh All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: * Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. * Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution. * Neither the name of ISPConfig nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission. THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ ini_set('register_globals',0); $conf["app_title"] = "MyDNSConfig"; $conf["app_version"] = "1.1.0"; $conf["rootpath"] = "/usr/share/mydnsconfig"; $conf["fs_div"] = "/"; // File system divider, \\ on windows and / on linux and unix $conf["classpath"] = $conf["rootpath"].$conf["fs_div"]."lib".$conf["fs_div"]."classes"; $conf["temppath"] = $conf["rootpath"].$conf["fs_div"]."temp"; /* Database Settings */ $conf["db_type"] = 'mysql'; $conf["db_host"] = 'localhost'; $conf["db_database"] = 'mydns'; $conf["db_user"] = 'mydns'; $conf["db_password"] = 'mydnspassword'; /* External programs */ $conf["programs"]["wput"] = $conf["rootpath"]."/tools/wput/wput"; /* Themes */ $conf["theme"] = 'grey'; $conf["html_content_encoding"] = 'text/html; charset=iso-8859-1'; $conf["logo"] = 'themes/default/images/mydnsconfig_logo.gif'; /* Default Language */ $conf["language"] = 'en'; /* Auto Load Modules */ $conf["start_db"] = true; $conf["start_session"] = true; /* DNS Settings */ $conf["auto_create_ptr"] = 1; // Automatically create PTR records? $conf["default_ns"] = 'ns1.example.com.'; // must be set if $conf['auto_create_ptr'] is 1. Don't forget the trailing dot! $conf["default_mbox"] = 'admin.example.com.'; // Admin email address. Must be set if $conf['auto_create_ptr'] is 1. Replace "@" with ".". Don't forget the trailing dot! $conf["default_ttl"] = 86400; $conf["default_refresh"] = 28800; $conf["default_retry"] = 7200; $conf["default_expire"] = 604800; $conf["default_minimum_ttl"] = 86400; ?>
Afterwards, remove the MyDNSConfig installer from the /tmp directory:
rm -rf MyDNSConfig-1.1.0/
rm -f MyDNSConfig-1.1.0.tar.gz
4 Installing MyDNS
Next we download the mydns-mysql rpm package from http://mydns.bboy.net/download/ and install it as follows:
rpm -ivh mydns-mysql-1.1.0-1.i386.rpm
Open the MyDNS configuration file /etc/mydns.conf, fill in the correct database details, allow zone transfers by setting allow-axfr to yes, enable TCP (allow-tcp = yes), and specify a recursive resolver (i.e., a valid nameserver, e.g. from your ISP; e.g. recursive = 220.127.116.11) so that MyDNS can answer queries for domains that it isn’t authoritative for:
## ## /etc/mydns.conf ## Wed Jan 18 17:18:48 2006 ## For more information, see mydns.conf(5). ## # DATABASE INFORMATION db-host = localhost # SQL server hostname db-user = mydns # SQL server username db-password = mydnspassword # SQL server password database = mydns # MyDNS database name # GENERAL OPTIONS user = nobody # Run with the permissions of this user group = nobody # Run with the permissions of this group listen = * # Listen on these addresses ('*' for all) no-listen = # Do not listen on these addresses # CACHE OPTIONS zone-cache-size = 1024 # Maximum number of elements stored in the zone cache zone-cache-expire = 60 # Number of seconds after which cached zones expires reply-cache-size = 1024 # Maximum number of elements stored in the reply cache reply-cache-expire = 30 # Number of seconds after which cached replies expire # ESOTERICA log = LOG_DAEMON # Facility to use for program output (LOG_*/stdout/stderr) pidfile = /var/run/mydns.pid # Path to PID file timeout = 120 # Number of seconds after which queries time out multicpu = 1 # Number of CPUs installed on your system recursive = 18.104.22.168 # Location of recursive resolver allow-axfr = yes # Should AXFR be enabled? allow-tcp = yes # Should TCP be enabled? allow-update = no # Should DNS UPDATE be enabled? ignore-minimum = no # Ignore minimum TTL for zone? soa-table = soa # Name of table containing SOA records rr-table = rr # Name of table containing RR data soa-where = # Extra WHERE clause for SOA queries rr-where = # Extra WHERE clause for RR queries
Next, create the system startup links for MyDNS and start MyDNS:
chkconfig –levels 235 mydns on
Finally, we need to fix the system startup links for MyDNS. MyDNS depends on MySQL, so MyDNS must start after MySQL has started, otherwise it will fail. The default startup links for MyDNS make it start before MySQL which is wrong, so we fix this as follows:
mv S52mydns S99mydns
mv S52mydns S99mydns
mv S52mydns S99mydns
MySQL uses the startup links S64mysql, so renaming the MyDNS startup links from S52mydns to S99mydns makes sure that MyDNS starts after MySQL.
The basic installation of MyDNS and MyDNSConfig is now finished. To log in to the MyDNSConfig interface, open a web browser and enter enter the following URL:
Replace <your_ip_address> with the IP address of your server.
The default username and password of MyDNSConfig are:
Don’t forget to change the password after login under System > Users.
5 Using MyDNSConfig
In this chapter I will demonstrate how to use MyDNSConfig by creating an example zone test.com and an A record www.test.com.
First log in:
Click on the Add New Zone button:
The form on the SOA tab is preseeded with default values. Fill in test.com. (please note the final dot!) in the Origin field and make changes to the other fields, if necessary. The Zone Transfers field can be left empty which means that any server can connect to our MyDNS server to initiate a zone transfer; if you fill in an IP address, only that system can connect:
After you’ve clicked on Save, you will find your new zone listed on the Zones (SOA) page. Click on the test.com. link to go to the zone’s properties:
Next, click on the Records tab:
Then click on the Add New Record button to create a record (A/MX/CNAME/…):
To create the A record www.test.com, fill in www in the Name field, select A as the Type, type in www.test.com‘s IP address in the Data field (e.g. 22.214.171.124), and specify the TTL (in seconds). The Preference/Priority field can be left empty for A records; it’s needed for MX records:
After you’ve clicked on Save, you will find www.test.com in the list of records for the zone test.com:
That’s it already – no restarts are required. You can now test if MyDNS can resolve www.test.com:
dig @localhost www.test.com
If all goes well, the output should look something like this:
[root@server1 ~]# dig @localhost www.test.com
; <<>> DiG 9.5.0a6 <<>> @localhost www.test.com
; (1 server found)
;; global options: printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 55393
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0
;; QUESTION SECTION:
;www.test.com. IN A
;; ANSWER SECTION:
www.test.com. 86400 IN A 126.96.36.199
;; Query time: 24 msec
;; SERVER: 127.0.0.1#53(127.0.0.1)
;; WHEN: Mon Dec 3 23:47:14 2007
;; MSG SIZE rcvd: 46
- MyDNS: http://mydns.bboy.net
- MyDNSConfig: http://www.mydnsconfig.org
- CentOS: http://www.centos.org