Dynamic DNS support for WHM using ddclient

benny — Wed, 20 Jan 2010 23:11:01 +0000

The server which I use to use to host my websites is now primarily used as my DNS and also a backup ftp space for this server to store backups (that way I don't have to buy some sort of tape backup thing). This is great except for the fact that my IP changes a couple of times a year. Up until now I was pushing requests from the webhost's DNS to dyndns and then to my home server running ddclient to update dyndns. Of course I could have paid around $30 a year per domain but I'm cheap.

So I modified ddclient so that it would update my host's DNS server. My host uses cpanel/WHM which luckily has a JSON API!

Here's how you can make the same modifications:

Install ddclient on your server - this is easy

yum install ddclient

You're also going to need some perl mods:

cpan

note: don't just copy and paste these 4 lines at once, some of the installs may have you type "yes" at some point. In the case of WWW::Mechanize, it forced me to type "yes" at least 4 times.

install JSON
install JSON::XS
install WWW::Mechanize
exit

Now, make sure you have version 3.7.3 of ddclient and then patch it with this ddclient 3.7.3 patch file

cd /tmp
wget http://blog.bennyland.com/wp-content/uploads/2010/01/ddclient.tar.gz
tar -zxvf ddclient.tar.gz
cd ddclient patch -p0 /usr/sbin/ddclient < ddclient.patch

Alternatively you can follow these directions:

vim /usr/sbin/ddclient

replace this:

require 5.004;
use strict;
use Getopt::Long;
use Sys::Hostname;
use IO::Socket;

with:

require 5.004;
use strict;
use Getopt::Long;
use Sys::Hostname;
use IO::Socket;
use WWW::Mechanize;
use JSON -support_by_pp;

replace this:

    'sitelutions' => {
        'updateable' => undef,
        'update'     => \&nic_sitelutions_update,
        'examples'   => \&nic_sitelutions_examples,
        'variables'  => merge(
                          { 'server'       => setv(T_FQDNP,  1, 0, 1, 'www.sitelutions.com',   undef)    },
                          { 'min-interval' => setv(T_DELAY,  0, 0, 1, 0, interval('5m')),},
                          $variables{'service-common-defaults'},
                        ),
    },

with:

    'sitelutions' => {
        'updateable' => undef,
        'update'     => \&nic_sitelutions_update,
        'examples'   => \&nic_sitelutions_examples,
        'variables'  => merge(
                          { 'server'       => setv(T_FQDNP,  1, 0, 1, 'www.sitelutions.com',   undef)    },
                          { 'min-interval' => setv(T_DELAY,  0, 0, 1, 0, interval('5m')),},
                          $variables{'service-common-defaults'},
                        ),
    },
    'whm' => {
        'updateable' => undef,
        'update'     => \&nic_whm_update,
        'examples'   => \&nic_whm_examples,
        'variables'  => merge(
                          { 'min-interval' => setv(T_DELAY,  0, 0, 1, interval('5m'), 0),},
                          $variables{'service-common-defaults'},
                        ),
    },

replace this:

sub split_by_comma {
    my $string = shift;

    return split /\s*[, ]\s*/, $string if defined $string;
    return ();
}

with:

sub split_by_comma {
    my $string = shift;

    return split /\s*[, ]\s*/, $string if defined $string;
    return ();
}
sub split_by_semi {
    my $string = shift;

    return split /\s*[; ]\s*/, $string if defined $string;
    return ();
}

and at the very bottom of the file replace this:

######################################################################
# vim: ai ts=4 sw=4 tw=78 :

with:

######################################################################

######################################################################
## nic_whm_examples
######################################################################
sub nic_whm_examples {
    return <" . $record{name};
                        $url_lookup     = "http://$config{$h}{'server'}/json-api/editzonerecord";
                        $url_lookup .= "?domain=$host_to_update";
                        $url_lookup .= "&Line=$record{Line}";
                        $url_lookup .= "&address=$ip";
                        my $api_update_output = json_whm_fetch($config{$h}{'login'},$config{$h}{'password'},$url_lookup);

                        if (json_whm_status($api_update_output) != 1)
                        {
                                failed("updating '%s' - '%s': %s %s", $host_to_update, $record{name}, json_whm_status_msg($api_update_output), $url_lookup);
                                $has_failed = 1;
                                $config{$h}{'status'} = 'failed';
                        } else {
                                success("updating '%s' - '%s': good: IP address set to %s", $host_to_update, $record{name}, $ip);
                        }
                     }
                } else {
                        # warning("name '%s' not found for host '%s'", $record{name}, $host_to_update);
                }
        }

        if ($has_failed == 0)
        {
          $config{$h}{'ip'}     = $ip;
          $config{$h}{'mtime'}  = $now;
          $config{$h}{'status'} = 'good';
        }
    }
}
sub json_whm_a_records
{
        my(%json) = %{(shift)};
        my(@records) = @{($json{result}[0]{record})};
        my(@a_records);
        foreach (@records)
        {
                my(%record) = %{($_)};
                if ($record{type} eq "A")
                {
                        push(@a_records, \%record);
                }
        }
        return \@a_records;
}
sub json_whm_status
{
        my(%json) = %{(shift)};
        my $status = $json{result}[0]{status};
        return $status;
}
sub json_whm_status_msg
{
        my(%json) = %{(shift)};
        my $status = $json{result}[0]{statusmsg};
        return $status;
}
sub json_whm_fetch
{
        my ($whm_api_login) = $_[0];
        my ($whm_api_key) = $_[1];
        my ($json_url) = $_[2];
        my $browser = WWW::Mechanize->new();
        my @args = (
                Authorization => "WHM " . $whm_api_login . ":" . $whm_api_key
        );
        my $json_text = "";
        eval{
                # download the json page:
                # print "Getting json $json_url\n";
                $browser->get( $json_url, @args );
                my $content = $browser->content();
                my $json = new JSON;

                # these are some nice json options to relax restrictions a bit:
                $json_text = $json->allow_nonref->utf8->relaxed->escape_slash->loose->allow_singlequote->allow_barekey->decode($content);
        };
        # catch crashes:
        if($@){
                print STDERR "[[JSON ERROR]] JSON parser crashed! $@\n";
                return "";
        } else {
                return $json_text;
        }
}

######################################################################
# vim: ai ts=4 sw=4 tw=78 :

Save and close ddclient

:wq

Now, edit ddclient.conf.

vim /etc/ddclient/ddclient.conf

Here's a simple version (note: you need to log into WHM and get your API key or none of this is going to work. You'll be entering your API key as one line - in WHM it is copied as several lines, just remove the carriage returns and enter it in one huge line as your password). Notice how my domain looks, it's my domain name, followed by a colon, followed by colon seperated hostnames to update - they all have periods after them!

daemon=300                              # check every 300 seconds
syslog=yes                              # log update msgs to syslog
mail=root                               # mail all msgs to root
mail-failure=root                       # mail failed update msgs to root
pid=/var/run/ddclient.pid               # record PID in file.
ssl=yes                                 # use ssl-support.  Works with
                                        # ssl-library
## To obtain an IP address from Web status page (using the proxy if defined)
use=web, web=checkip.dyndns.org/, web-skip='IP Address' # found after IP Address

##
## WHM
##
server=host.or.ip.of.your.whm.maybe.with.port,       \
protocol=whm,                   \
login=your-whm-username,                 \
password=crazy-long-api-key-as-one-long-line               \
hostname.com;hostname.com.;subdomain.hostname.com.

Save and close ddclient.conf

:wq

And finally run it and tell it to run every time the server reboots:

/sbin/chkconfig ddclient on
/sbin/service ddclient start

Bennyland » whm

Dynamic DNS support for WHM using ddclient