My iPaq, ActiveSync and the Firewall

I’ve been using iPAQs for some time now (though I’ve been switching between models) and I’ve always used ActiveSync to synchronise my device to both my home PC and office PC. I haven’t had any problems with synching until a couple of weeks ago when my office PC refused to connect with my iPAQ PDA.

At first I thought it was the PC that was at fault. I’ve been getting other memory leak type errors from it at about the same time so I suspected the synch problem to be related to it.

I’ve been given with a spiffy new office PC recently but I was surprised to discover the synch problem still present. I then realised that the cause of the problem was something else entirely. After a bit of research on the web, I found out the culprit: our office firewall!

According to Microsoft’s Windows Mobile ActiveSync 4.0/4.1/4.2 USB Connection Troubleshooting Guide:

Most cases of ActiveSync 4.x USB connection problems as listed above are caused by Windows desktop firewall applications or applications that manipulate network traffic. These applications conflict with the TCP traffic between your device and the PC, causing data transfer and connection issues. The list below provides some known applications that may cause problems connecting your device to your PC.

If this was a problem with my home PC, I could fix it very easily. However, this is the office PC I have to deal with here and I don’t have sufficient permission/access rights to modify the settings of the firewall application. I talked to our network administrator about it and he told me what I already suspected. The firewall was set to block almost all network traffic and he was a bit unwilling to modify the settings. So, the only way to synch my PDA to the office PC was to disable the firewall everytime I had to synch. It’s such a pain to do, not to mention risky.

I continued my search for a workaround the problem that didn’t involve modifying firewall settings, basically bypassing it entirely. After following forum threads about the topic, I eventually found a discussion about other Windows Mobile 5.0 PDA devices and issues with ActiveSync.

One of their suggestions was to install a handy little utility called USBSwitch_PPC.cab on your Windows Mobile 5.0 PDA. The application called USB Killer will be installed on your PDA. Run it and change the ActiveSync Mode from RNDIS to Serial. Serial mode is the old way PocketPC PDAs synch with PCs. It may be slower than the current method that uses TCP/IP protocols, but at least the firewall ignores serial connections.

And now, I’m able to synch my PDA to my office PC without having to shutdown the firewall software first.

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Published in: on February 13, 2007 at 1:38 am  Leave a Comment  

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