I'm using dyndns with pfSense and I have a router connected on the WAN line (DHCP configuration). Every few days my ISP changes my IP but pfsense does not update it automatically.
If I open the WebUI and visit the dynamic DNS service it shows my IP in red color because it detects that it's not the current one. If I click "save and update" it correctly updates the IP.
How can I make pfSense automatically update the IP?
It appears that this is a known limitation[1] when pfsense is connected with your modem/router using TCP/IP (either static or dynamic). The workaround is this:
Install the cron package (System > Package Manager > Available Packages, search for cron and click INSTALL). Then go to Services > Cron and click edit(the pencil) on the line about rc.dyndns.update. You need to change the Minute to */5 and Hour to *. This will make pfsense to check for IP changes every 5 minutes.
Notes [1] There is a closed bug report https://redmine.pfsense.org/issues/2148 where the pfsense team suggests this workaround. They note that "the cron package allows editing that easily, don't think it's worthwhile for us to bother"