Posted on 04-10-2008 under linux

I just registered for No-IP.com, just to see what my server would look like from the web. Brilliantly, the No-IP dynamic update program is available on Debian. A quick

 aptitude install noip2

and I was enjoying the joys of being url accessible.

Not surprisingly my ISP soon hiccuped, causing me to lose my IP address. This was the perfect test for No-IP.

Which went bad. It soon became apparent that no-ip wasn’t doing what it was meant to. After looking through the excellent guide by No-IP, forum posts, and more, I still couldn’t get it to run.

It then occurred to me that the utility could be using a different port, one that would be blocked by my firewall. So I tried a really risky, “disable firewall” test. And what do you know, no-ip worked just fine. So the problem was with the port, but which one? I can’t test all 65,536 ports!

Since I already had the utility’s source code, as I had followed their guide, I looked through the files. Thankfully there was only one C file, and a quick look uncovered this line.

 #define CLIENT_IP_PORT		8245

Bloody ****, if you had only told us there was a port you needed ….

Problem fixed. But I shouldn’t have had to muck about in the code in the first place. No-IP is a business and they could lose customers this way. The guide was written for complete laymen, and such a person just cannot go looking through code. Proper documentation is necessary people.

Then again, if No-IP hadn’t given us the code, I wouldn’t have found that port so easily.

[Update] Please read No-IP continued for updates.