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I've done a bit of searching on the internet trying to find out whether there is an INBOUND TCP connection limit on Windows 7.

We're writing a server product which processes data from a number of embedded nodes. These nodes connect over TCP to the server.

We're wondering whether we can get away with Windows 7 to run the server application rather than having to pay for Server 2008.

We're not using any of the Microsoft protocols however we may use IIS on the server for client applications to connect to view data from the embedded nodes.

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Check the comment by snakefoot at the bottom of this article..smallvoid.com/article/winnt-tcpip-max-limit.html... As far as I can read there is no difference between W7 and 2008 and the tcpip stack configuration –  Moab Mar 4 '11 at 14:15
    
See this also...microsoft.com/downloads/en/… –  Moab Mar 4 '11 at 14:16
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5 Answers

Running 'net config server' at the command-line suggests that Windows 7 can support up to 20 inbound / 20 outbound incomplete connections.

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I don't suppose you're able to provide the output? I'm not seeing an entry for this when I run the command. –  Nick Mar 4 '11 at 12:07
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//net config server //Server Name \\MYPCNAME //Server Comment //Software version Windows 7 Enterprise //Server is active on // NetbiosSmb (MYPCNAME) // NetBT_Tcpip_{GUID here} (MYPCNAME) // NetBT_Tcpip_{GUID here} (MYPCNAME) // NetBT_Tcpip_{GUID here} (MYPCNAME) //Server hidden No //**Maximum Logged On Users 20** //Maximum open files per session 16384 //Idle session time (min) 15 //The command completed successfully. –  nimizen Mar 4 '11 at 13:02
    
@Nick You'll have to right click on command prompt and select 'run as administrator' or the command will just result in 'access denied'. –  Kara Marfia Mar 4 '11 at 13:03
    
Ah ok, so I'm actually looking for the maximum TCP connections rather than the number of login sessions. –  Nick Mar 4 '11 at 13:09
    
-1 These connections are not the same as TCP connections. –  Kevin Panko Nov 8 '13 at 18:18
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up vote 1 down vote accepted

This response on ServerFault answers the question:

A Windows Socket is basically the same concept as Berkley Sockets. Those have absolutely nothing to do with the 10 Connection limit you're looking at. The 10 Connection limit is an unenforced application session limit. Basically this is to prevent people from abuse XP as a public web server platform, file server, or something similar.

http://serverfault.com/questions/234131/do-tcp-udp-connections-add-to-the-windows-incoming-connection-limit

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I have experienced maximum connection limit problems in Windows XP and Windows Vista, and now I do all my server development on NetBSD Unix. I've not tried Windows 7, but I've heard that it's got the same limit.

The problem I ran into was that once we had 10 connection open, additional connection attempts would fail but in a strange way -- no error message but eventually it timed out. This limit was a maximum of 10 per TCP port number used, so you might be able to get around this if you're using different TCP port numbers.

There are a few hacking tools on the internet that will modify this limit in your TCPIP.SYS file, but these are not supported by Microsoft, and if you modify the wrong version of TCPIP.SYS then you'll be at risk of having a corrupt TCP/IP stack on your system. In addition to that, some of those tools were actually SpyWare, so you need to be very careful with this.

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Thanks Randolf. Were you just making plain-old TCP connections? Or were these windows-login connections? –  Nick Mar 7 '11 at 9:30
    
These were TCP connections (I'm writing an SMTP/POP3/IMAP4/<and-something-new> server in Java). Since each Windows login connection also uses a socket, these are effected in the same way. –  Randolf Richardson Mar 8 '11 at 16:59
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There doesn't seem to be any TCP connection limit on Windows 7. The last time I ran a P2P software and the TCP Connections was 500+, according to Resource Monitor.

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I would suggest that 65535 would be the maximum number of TCP connections permitted for an IPV4 Windows machine.

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Why do you think so? Can you provide a reference? –  Kevin Panko Nov 8 '13 at 18:19
    
Also which versions have this limit? –  pabouk Nov 8 '13 at 18:25
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