Category Archives: DNS

IPv4 DDNS on Cisco for dns.he.net

As dyndns.com has reduced the capabilities of their free service, I looked around for other free providers of Dynamic DNS service.

After testing several, I decided to move my DNS hosting to Hurricane Electric as they include Dynamic DNS service with their free service (for up to 50 domains), and it removes the requirement to use CNAMEs as with the dyndns.com free service.

The configuration as below is for IPv4 dynamic addressing as provided by most Internet Service Providers on xDSL or Cable (broadband) connections when using the free DNS and DDNS service as provided by dns.he.net

The below has been tested on a Cisco 1812 running c181x-advipservicesk9-mz.151-4.M4.bin on a BT FTTC connection which uses PPPoE over VDSL where the PPPoE interface has a dynamic address. It has also been tested on a Cisco 877 running c870-advipservicesk9-mz.151-4.M4.bin on several other UK ADSL and ADSL2+ connections

It does not cover changing the IPv4 termination address for a he.net IPv6 Tunnel.

In Global mode

ip ddns update method 
HTTP
 add http://<f.q.d.n>:<password>@ipv4.dyn.dns.he.net/nic/update?hostname=<h>&myip=<a>

Then on the dynamic addressed interface (usually Dialer 1)

 ip ddns update hostname <f.q.d.n>
 ip ddns update <method-name> host ipv4.dyn.dns.he.net

<method-name> This is the name that you want to give the DDNS update, I usually use dyn.he.net
<f.q.d.n> This is fully qualified domain name that is configured for Dynamic DNS on the dns.he.net control panel<password> This is the password for the fully qualified domain name that is configured for Dynamic DNS on the dns.he.net control panel
<h> This is an internal Cisco IOS variable for the hostname that it gets from the configuration on the interface
<a> This is an internal Cisco IOS variable for the dynamic address on the interface

Presuming that the method name is dyn.he.net, the dynamic hostname being used is router.domain.com and the password is SuperSecretPassword the completed configuration commands should look something like this

In Global mode

ip ddns update method dyn.he.net
HTTP
add http://router.domain.com:SuperSecretPassword@ipv4.dyn.dns.he.net/nic/update?hostname=<h>&amp;myip=</h>

Then on the dynamic addressed interface (usually Dialer 1)

ip ddns update hostname router.domain.com
ip ddns update dyn.he.net host ipv4.dyn.dns.he.net

It is not possible to copy and paste all of the config directly into a console session as the line that begins with “add” contains a question mark.

To enter a question mark ? in IOS, press and hold ctrl, press v, release both keys, then press ?