So I’m working with a group at our company that is fond of shared Microsoft Exchange Calendars. I’m a pragmatic fellow and while I have run Linux as my day-to-day platform for 10 years now I just realize that the world sometimes sees stuff differently from me. Whatever… I really don’t mind. It’s just a program. Run it.

Let’s just boot Windows in a VMWare virtual machine and run Outlook’s Calendar. Easy as pie. Wrong.

I use OpenSSH to tunnel into our work network. I map a slew of local ports to remote machines over the SSH connection. So what ports need to be mapped to the Exchange server. Answer: All of them.

Exchange is built upon MS-RPC which is a tweaked version of OSF DCE/RPC and all of these protocols seem to just love to dynamically allocate ports to serve individual clients. I saw it in Wireshark myself. Outlook connects to the exchange server over port 153 and the reply points Outlook to another port to continue the conversation.

At this point I am filled with colorful epithets that I’ve disciplined myself not to utter verbally.

I know very little about all of these protocols. Wikipedia this stuff:

• “MSRPC (Microsoft Remote Procedure Call) is a modified version of DCE/RPC.”
• “DCE/RPC stands for “Distributed Computing Environment / Remote Procedure Calls”.
• “Distributed Computing Environment (DCE) is a software system developed in the early 1990s by a consortium…”

Eh… hold it. A consortium? Oh, that explains some of this. Tell me more…

“As part of the formation of OSF, various members contributed many of their ongoing research projects. At the time, network computing was quite popular, and many of the companies involved were working on similar RPC-based systems. By re-building these various utilities on a single “official” RPC mechanism, OSF could offer a major advantage over SVR4, allowing any DCE-supporting system (namely OSF/1) to interoperate in a larger network.”

So MSRPC is based on DCE/RPC which is based on a bunch of corporate R&D cast-offs? (maybe cast-offs is a little harsh)

I’m just dubious about a closed door corporate consortium getting stuff right. There is a huge difference between a community centric development model with corporate participation (like the Eclipse community) and a corporate consortium populated with commercial actors even if the intended output of the consortium is to be licensed under a FLOSS license.

I have no clue if a real community would have reigned in the madness of dynamic ports. Maybe they were de rigueur at that time. I have a hunch it would have been different, though.

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This entry was posted on Wednesday, May 7th, 2008 at 5:00 pm and is filed under community.