Problem Solving

A recent conversation with an Apple consultant reminded me how different solutions to the same problem can be.

We had both encountered the same issue with Safari having difficulty with NTLM authentication. This meant all our Apple based hardware was having trouble authenticating against our proxy server. Both our solutions involved the same software, Firefox but our implementations were very different.

Firefox as standard does not read the proxy information from the OS. My solution was to use a plugin installed for all users that read the system proxy and applied it to safari. This gave me the freedom to change the proxy in the future with a simple networksetup command.

The consultant used an edited plist file that set the proxy for firefox. This was an incredibly simple solution but one I felt didn’t give as much freedom for future changes.

We talked a little more and I mentioned an interesting bug I had recently solved. All our Apple hardware dual boots running Vista and Leopard. However both OS’s authenticate against Active Directory.

On arriving to work after the daylight savings clock correction [thankfully on time] leopard would no longer authenticate. After a little bit of testing we discovered booting into Vista then Leopard broke authentication. For some reason the clock was always an hour fast. This was truely puzzling as if you logged on locally restarted into Leopard it would authenticate and the time would be correct.

This pointed to an issue in Vista causing the time to slip breaking authentication. After some research on MSDN I discovered Vista does not write to the RTC using UTC whereas all other OS’s use the UTC format. So everytime a machine was booted into vista it wrote the wrong time to the RTC. The solution was to add a registry key to change Vista’s behaviour . This change worked and reminded me the majority of authentication problems come down to time or DNS.

Microsoft have since added UTC support in Vista SP2 so this problem should not occur on future installs.

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