NT Workstation 4.0 Limit on IP Connections

07/19/1996 (revised)

Microsoft has backed down:

Hmm, they really haven't backed down:
MS NT Workstation 4.0 Maintaining Limitations

You may have already heard that in Microsoft's upcoming NT Workstation 4.0, functionality will be significantly reduced. If you want to run any Web server -- O'Reilly's, Microsoft's, or others' -- on NT, you'll have to buy NT Server for $999. The implications of Microsoft's actions are serious for the Web community, and I encourage you to help spread the word about it.

First, the facts: NT Workstation 4.0 will limit the number of unique IP addresses which can contact a Web server to 10 or fewer in a 10-minute period. Here is a description from Microsoft (note that HTTP, port 80, is one of the "reserved" ports):

An inbound TCP connection is attempted. The stack first checks to see if the connection is destined for a reserved port (the first 1024 are "reserved" ports). If the target port is NOT one of reserved ports then we immediately grant the connection attempt. If the target is the NetBT port, the connection is granted to the NetBT handler for further processing. This logic allows custom peer to peer distributed applications (ie. Plant automation, trading floors) to work just fine. It also allows for callback operations like those used by Xservers or FTP GET to also function.

For connections targeted to the reserved ports, the stack checks for a previous instance of the connecting IP address in a fixed table of ten entries. If the address was not found and there is a free slot in the table, then a fresh entry is made listing the connecting source and timer (ten minutes) is started on that entry. If the entry previously existed, its timer is reset to ten minutes. If the table is full and the connecting address was not found, the connection is rejected.

Of course, this effectively eliminates NT Workstation as an option for Internet or Intranet development. In contrast, the previous version of NT Workstation 3.51 contains no limits on the number of IP addresses which contact a Web server.

Now, the implications: this development will choke off one of the most important new directions for the Web, its return to its roots as a groupware information sharing system for the desktop. Like email and the PC itself, Web publishing belongs on the desktop. With the likely higher price tag of NT Server, users who have never before put up a web site will be extremely unlikely to do so.

This move by Microsoft will hurt the efforts of Internet service providers, Web developers, and Intranet developers, a great many of whom have been happy to create sites on NT Workstation. Microsoft has been saying that IIS (the Web server they plan to include with NT Server 4.0) is free, and quite clearly, this is now exposed as untrue. Developers will have to stick with the older operating system if they want to use any server other than IIS, or will have to upgrade and pay extra for the server of their choice.

WebSite developer Bob Denny says: "When I first started developing Winhttpd in 1994, nearly all Web serving was done on the Unix platform. Considering that companies such as O'Reilly & Associates, Netscape, Process, and a half dozen more, pushed hard in the fight to legitimize NT vs. Unix as a Web server platform over the last 18 months, Microsoft's actions are pretty extreme."

I've sent email to Bill Gates to let him know of my personal concern about the impact of his plans on Web users and developers. I encourage anyone interested in maintaining the open systems nature of the Web to send email to Microsoft, post this news on their sites and in newsgroups, and write letters to editors, to put pressure on Microsoft to reverse their decision. They've reversed such decisions before.

Tim O'Reilly