What

These steps will install ddclient on your Ubuntu server and allow it to update any Cloudflare domains you want with your current dynamic IP address. The computer on which you install this script should be one that remains at the same location as the dynamic IP you'd like to link.

Why

Let's say you want to host a VPN server, a website, your files or anything else at home. Unless you have a static IP address, which in some cases you can't get without signing up for a business account, you'll need a way to associate your dynamic IP address with a domain name so your service doesn't get interrupted when your assigned public IP changes.

Which Technologies

This guide focuses on installing ddclient on Ubuntu (I used 16.04 server) and integrating it with Cloudflare. There are many other installation methods, so check out the ddclient repo for a full list.

How

Ssh into your Ubuntu machine and become the root user:

ssh username@ipaddress.of.machine -p port_you_set_default_is_22
sudo su

Next clone/download the ddclient repo from Github. I used the /tmp directory, but you can use whatever you want. Move to that directory:

cd /tmp

Clone the repo into the directory you chose:

git clone https://github.com/ddclient/ddclient.git

Next enter the new ddclient directory and copy ddclient to /usr/sbin:

cd /tmp/ddclient
cp ddclient /usr/sbin/

Make a couple directories that are missing:

mkdir /etc/ddclient
mkdir /var/cache/ddclient

Once those directories are made, copy the default config to use as your starting place:

cp sample-etc_ddclient.conf /etc/ddclient/ddclient.conf

Open that file for editing:

vim /etc/ddclient/ddclient.conf

Once in Vim, you want to hit i to enter insert mode, at which point you'll be able to enter text. The first thing to do is to remove the # at the beginning of this line:

use=web, web=checkip.dyndns.org/, web-skip='IP Address’

Now search for the Cloudflare section by hitting the escape key to exit insert mode and then typing a / and then cloudflare an hitting enter. That should bring you to the section. Once there, set it up by first removing the # from beginning of each line and then changing everything that starts with a $ below to your personal details:

protocol=cloudflare,        \
zone=$domain.tld,            \
login=$your@cloudflare.login,     \
password=$your_api_key             \
ttl=1                       \
$domain.tld,$subdomain1.domain.tld,$subdomain2.domain.tld

A couple notes about the lines above: make sure the password line does not end in a comma. You can update as many domains and subdomains as you'd like by placing them on the last line of the config block but remember they will all be set to the same IP.

Hit escape again to exit insert mode and hit : and type wq then hit enter to save and exit vim.

Now you're ready to test your setup with the following command:

ddclient -daemon=0 -debug -verbose -noquiet

It may (and probably will) fail and that's just fine; there are a variety of errors that I discuss at the bottom of this readme. Each time you correct an error, run the above command to test whether it corrected that specific error.

Once everything is working, perform one final test by changing one of your Cloudflare DNS entries of a domain you want associated with your dynamic IP to something that isn't your dynamic ip, then run the test command above and verify that it did, in fact, change it back. Once you see that you know you're good.

Now you're ready to set ddclient to run at startup and launch it on boot. If you've changed directories, go back to where you initially cloned the ddclient repo, for me that was /tmp/ddclient by entering:

cd /tmp

Copy the Ubuntu launch script to your /etc/init.d folder and enable it on boot:

cp sample-etc_rc.d_init.d_ddclient.ubuntu /etc/init.d/ddclient
update-rc.d ddclient

Finally, start the service manually the first time:

service ddclient start

In order to double check that everything is set up correctly, run ddclient -query and make sure that this line is correct: use=web, web=dnspark address is your.public.ip. In order to access the query mode, press control+c. After the script has run a couple times you'll also want to check the "mail" that the script is creating because there may be one more issue. Open the mail by running:

sudo vim /etc/mail/root

If you see an error that looks like this:

WARNING:  file /var/cache/ddclient/ddclient.cache, line 3: Invalid Value for keyword 'ip' = ''

you may need to update the version of ddclient. The error has been fixed in more recent versions, but this post explains a bit about what's going on.

Possible Errors + Their Solutions

Can't locate Data/Validate/IP.pm in @INC (you may need to install the Data::Validate::IP module)

apt-get install libdata-validate-ip-perl

FATAL: Error loading the Perl module JSON::Any needed for Cloudflare update.

apt-get install libjson-any-perl

Can't exec "sendmail": No such file or directory at /usr/sbin/ddclient line 1584.

apt-get install sendmail

WARNING: local host name (server) is not qualified;

This is an error that sendmail may give you on install. If you want, you can change your hostname to be something like server.domain.com, which would be qualified. This is not necessary, though.

Error loading the Perl module IO::Socket::SSL needed for SSL connect.

apt-get install libio-socket-ssl-perl

Final Thoughts

That's it! Your setup should be complete. Please let me know if you encounter any errors that aren't listed below and submit a pull request if you have any corrections, additions or improvements.

Matt