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Looking through a Windows 8 installation I noticed that Microsoft changed the half open TCP collection limit to unlimited.

It was previously argued that a limit helps stem the spread of malicious software.

Why was the limit removed? Does Microsoft's own software use a torrent style download protocol or some other wacky reason?

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This begging for opinion, as MS are not generally inclined to comment on these things. The answer is probably that it caused more problems than it solved. – Paul Nov 3 '12 at 12:28
up vote 6 down vote accepted

This is not New to Windows 8, it started back with Vista SP2

Microsoft appears to have a change of heart on the half-open outbound TCP connection attempts limit with the release of Windows Vista SP2 and Windows 7, probably due to the fact that the limit never effective in stopping the spreading of worms and viruses, or Microsoft has grown more confident about security feature of newer operating system.

According to Notable Changes in Windows Server 2008 SP2 and Windows Vista SP2 document published in conjunction with the release of SP2 RTM:

SP2 removes the limit of 10 half open outbound TCP connections. By default, SP2 has no limit on the number of half open outbound TCP connections.

The complete removal of the limit for half-open outbound TCP connections, which is defaulted to 10, was finalized with the release of Windows Server 2008 and Vista SP2 Build 17506. In fact, the half-open outgoing TCP connection limit has been bypassed by default since Windows Vista SP2 RC Build 16670. Previously, the changelog of SP2 showed that Microsoft looks like going to “add a registry key that enables modification of the maximum number of open TCP connections to increase application compatibility”.

Source of Information

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