Dynamic DNS

Dynamic DNS, even standard DNS services that offer many configurable options can be expensive. The free ones or the ones that come with domain name registration are typically limiting and most do not support dynamic IPs. I have been using one for a number of years from a co-location and service provider called Hurricane Electric http://he.net/.

I learned about this provider while living in the Bay Area outside San Francisco. They would host a Linux user group and as a matter of fact still do 20 years later! EBLUG http://www.eblug.org/

One of the many great services HE provides is a free DNS service that contains the ability to configure dynamic DNS entries in the event you have a dynamic IP on your internet connection or need an easy way to failover some internet facing service with something a little less expensive than a GSLB. The service has been limited to 50 zones for the free version. Com'on!! For real??? Everyone owns more than 50 domain names... NOT! This is super cool of them to not only offer this service for real but then allow users to host 50 zones!

Getting started is easy. Once you have a domain registered, either new or existing, simply point your root name servers to HE's servers. Let's use the domain vmuglabs.net. I use GoDaddy for my domains so once in DNS management browse over to Nameservers. Once there change the GoDaddy name servers to HE's. They are:

ns1.he.net
ns2.he.net
ns3.he.net
ns4.he.net
ns5.he.net

Now if you don't have an account at HE go over to https://dns.he.net and register for an account.

Once logged in you can add a new zone or domain from the menu on the left

Once created you can edit the zone by selecting the edit icon just to the left of the domain name. Within the zone you will find 6 total records, 1 SOA and 5 NS records. Next is to create an A record and investigate how the ddns option works.

Once created you will need a way to authenticate to dynamically change the IP for the A record. HE uses a DDNS key, not your login account. To generate one select the change symbol.

Generate a key and copy it.

Once you have the key its time to build the bash script to facilitate the ddns change. the code can be located in github.

https://github.com/craigeherring/he-ddns

Run this script and if your IP changes your DNS record will be changed. To test you can manually change the IP within the HE DNS console and observe it changing back when the script is run.