Sun 13 Nov 2011
Category : Technology/DNSAgentUpdate.txt
I've updated both the Lion and Snow Leopard versions of DNS Agent, my app for dynamically updating dyndns.com's servers with your Mac's current public IP address.
In April last year, I updated DNS Agent for Snow Leopard to 1.0.1 because I realised that dyndns.com servers have started to ignore pings, by working in stealth mode. I ping the dyndns servers to make sure that they were available before attempting to make my updates. So, since pings don't work, I check instead that the DNS Server is actually listening on the appropriate port (for updates from clients) before trying to update to server.
Then sometime recently, dyndns.com servers have also started to ignore telnet probes on these well-known ports. So since these checks don't work anymore, DNS Agent gets stuck waiting to update the dyndns.com server.
So, with version 1.0.3 of DNS Agent for Snow Leopard (and version 2.0.1 of DNS Agent for Lion), I now stop doing these checks and simply proceed to update the dyndns.com server, trusting that it would be there, as they should be.
This should probably (reasonably) work almost all the time. I log any failure to update the dyndns.com server, but up to now, my log shows that updates do work all the time.
It needs more thought. I'll update the app again when I have a better idea.