XP SP2: TCP/IP has reached the security limit

Windows XP Service Pack 2 limits the number of simultaneous incomplete outbound TCP connection attempts, after the limit has been reached, subsequent connection attempts are put in a queue, it can limit the speed at which malicious programs, such as viruses and worms, spread to uninfected computers but also certain security tools, such as port scanners run more slowly or some P2P apps may fall foul of this, too.

Under normal operation, when applications are connecting to available hosts at valid IP addresses, no connection rate-limiting will occur. When it does occur, an event ID 4226 appears in the system's event log, more details could be find here.

The "TcpNumConnections" (MS KB 314053) registry entry doesn't seems to affect the limit on half open connections.

There is also an hacked dll on http://www.lvllord.de that workaround this limit even if I haven't tried it.
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Vittorio Pavesi

1 comments

  1. Anonymous
    10:41 PM

    On 22th of September Patcher Version 2.12 released!

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