I tried to connect 40 clients to a webservice that is on Windows XP and I get no connection.

Are the inbound TCP/IP connections on Windows XP limited to 10 at any one time?

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    The 10-connection hard limit is for SMB connections. – KCotreau Jul 11 '11 at 17:53
  • @Gold - did you really mean "webservice" or did you mean a file share? – James T Snell Jul 11 '11 at 18:01
  • Probably file share. – surfasb Jul 11 '11 at 18:17
  • i mean IIS - Webservice – Gold Jul 11 '11 at 19:03
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    See this duplicate question on server fault serverfault.com/questions/289136/… – Dave M Jul 11 '11 at 19:08

The TCP connection limit is not enforced, but it may be bound by legal agreement to not permit more than 10 clients.

See this from Microsoft: Inbound connections limit in Windows XP

In a command prompt type:

net config server

This shows max allowed logged on users, and max open files per session

  • That is amazing. That sounds like an extremely political decision. Dear Microsoft, I politely invite you to feel shame for that decision. Apologies/explanations are welcome. – James T Snell Jul 11 '11 at 17:46
  • +1 - AFAIK, this only affects incoming SMB sessions. IIS also respects this limit as well. 3rd party TCP services are not affected. – afrazier Jul 11 '11 at 19:01
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    @TheWhitePhoenix In all honesty why should Microsoft allow more connections, XP is a consumer operating system and has limits that are relevant for it, people can do most of the things they like with it, but if they want a server then they should buy a server grade OS... – Mokubai Jul 11 '11 at 19:01
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    If you want a server, get a server - XP is a workstation, it was not designed to be a server and it's not licensed to be a server - to ensure it's not used as such, MS imposed a limit to the number of simultaneous connections it can have. To me, this is perfectly justified. If you want to avoid the limit, try Linux. Otherwise, as I understand it, it's not SMB and it's not IIS - it's built in to the TCP/IP stack. – Multiverse IT Jul 11 '11 at 19:31
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    @Multiverse IT: If it were in the TCP/IP stack itself, BitTorrent or other P2P apps would fail in spectacular fashion. Besides artificial limitations, the network stack in Microsoft's client OSes is exactly the same as the server OSes, code-wise. – afrazier Jul 11 '11 at 20:40

Technically it is sessions. And it has nothing to do with TCP/IP.

This is to prevent the Home and Professional edition Windows from being used as Servers.

I don't blame them. If they supported more concurrent sessions, that would mean they would have to test that limit. Then fix whatever bugs that show up. And then more testing. All for a Home edition. . .

That's less time for features that the rest of us use. BTW, that limit was removed in Vista SP2.


The default connection limit for IIS on Windows XP is 10 connections. This can be increased to 40 connections, but not higher than that.

From http://weblogs.asp.net/cazzu/archive/2003/10/10/31476.aspx:

Find the adsutil.vbs script (should be in c:\inetpub\AdminScripts or similar) and run the following command:

adsutil set w3svc/MaxConnections 40

You can also disable "allow keepalives" in IIS which should allow you to serve connections faster, though it is still limited to the number of concurrent connections above. If it is a simple webservice, you shouldn't really need keepalives anyway.

Besides the obvious answer of purchasing a Server OS, or to use Apache for Windows (if you aren't running ASP.net apps), since it does not have the same limit that IIS has.


is Windows XP only allows 10 inbound TCP/IP connections at any one time ?

No, it definitely allows many more than that. Else how could people do things like run torrents?

Edit: According to Nicu's answer, I'm probably mistaken. I'm amazed by the link he provided. What complete (#profanity#).

i try to connect 40 client to my webservice that on Windows-XP and i get no connection

I'm not entirely sure what you really mean here. Are you running a local web server?

You can use various tools to help you see what's going on with your network. Task Manager gives a very basic view. "perfmon.exe" gives a lot more. And Wireshark gives tons of information. You can also try Event Viewer for hints.

Maybe you have some strange firewall setting that's causing this behavior? Do you have other network interfaces in your machine you can use to see if it's a hardware or interface-specific effect?

More detail about your particular situation may be helpful in providing meaningful answers. Take care


While your question is in regards strictly to inbound connections, I put this here just for a FYI.

Outbound connections are limited by Windows XP to help prevent viruses and malware from rapidly spreading and infecting a network (this was only patched after SP2).

The good news is that you can modify this limit using LvlLord's awesome tool. What this patch basically does is change the concurrent connection limit before event ID 4226 is triggered.

Before SP2, the maximum number of connections was virtually unlimited (technically, the maximum value of a 16-bit integer). LvlLord believes that 50 is a (sane) value that is good enough for most people. You can go higher if you wish, but do note that if you happen to get a virus, you'll also spread it much faster.

As an aside, I also believe nLite can perform this patch before creating an ISO (so you don't have to each time you format).

  • -1: The Event ID 4226 bits are about incomplete outbound connections, not inbound connections like the OP is asking about. – afrazier Jul 11 '11 at 18:59
  • @afrazier, you are correct, answer updated. – Breakthrough Jul 11 '11 at 19:06

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