PortICA Time Zone Support

This post is really about trying to catch up with what has been going on with PortICA Time Zone Support. For those of you that haven’t read about Citrix Time Zone Support, please look at my previous post. The idea is to preserve the user’s local time zone while working on a potentially very distant machine. Time is very important to the user and even though a server might be in London, the user in Sydney can’t accept the time difference from their sense of time.

Personally, even though I live in Australia, I still have trouble adjusting to remembering time differences between locations especially with daylight savings in effect in opposite directions. The point is that I don’t want to see a different time zone in effect on systems I would use remotely.

With PortICA, we use the same framework as Presentation Server for changing the time. However, there is a key difference. PortICA changes the time zone for real versus Presentation Server which virtualizes it per user. This means that when a user connects, PortICA will automatically re-adjust the time zone based on the client’s time zone. When the user logs off or disconnects, PortICA will automatically restore the time zone.

This implementation is much simpler than a virtual method. It also gives you full compatibility with all applications. There is a catch however. Now that PortICA really changes the time zone, the user must have the privilege to change the time (in XP). By default, only administrators and power users have the rights to change the time. It is possible to give other users the rights to change the time, but it requires two different categories of changes.

First, you must have the privilege to change the time on that system. This can be changed with GPOs (policies) or the local policies (if not in the domain). This privilege isn’t necessarily a light weight thing to be giving out but it is necessary to allow the time zone support to work with users in PortICA.

Secondly, you must change the registry rights for the time zone information on the machine to allow the user to change the time zone. This isn’t known as well. There is a Microsoft support knowledge base article about this.

Earlier in PortICA development we had a service that would do the work of changing the time zone for the users that didn’t have the rights to do so. This avoided the need to set policies or change registry security rights but was not considered a secure enough solution. The idea is that the administrators need to be responsible for privilege allocation. It’s the classic balance between usability versus security.

In a way this post is a heads up to the potential complexity of supporting time zone support on PortICA for XP. The good news from this story is that Vista doesn’t have this problem due to users given the rights to change the time zone isolated from changing the actual time. From this move, it appears Microsoft has considered the decision to connect changing the time and changing the time zone incorrect. I would agree. Changing the time zone does not change the core time and therefore is much less sensitive to security threats.

My bit of advice for this is to setup a group that has rights to the privilege and registry areas. Then it is just a matter of adding users into that group (which might be a different group like remote users) to get them access to changing the time zone for PortICA.

Overall PortICA is progressing very well and should be talked about a fair amount at the upcoming iForum in Las Vegas. It has been great to see this project reach critical mass and reach wider audiences.


Live near Brisbane, Australia. Software developer currently focused on iOS and Android. Avid Google Local Guide

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Posted in PortICA, Time Zone Support
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