SynAttackProtect is Enabled in Windows 7 by Default

[KEiGHT]

In red is wrong interpretation in windows 7 of SynAttackProtect

SynAttackProtect

This undocumented for Windows 7 setting provides protection against SYN denial of service (DoS) attacks. When enabled, connections timeout sooner if SYN attack is detected. When set at 1, TCPMaxDataRetransmissions can be lowered further.

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters
SynAttackProtect=1 (DWORD, recommended: 1, not present in registry by default)


Correct Answer

As of Windows Vista and onwards (Vista/2008/Win 7/2008 R2), syn attack protection algorithm has been changed in the following ways:

1) SynAttack protection is enabled by default and cannot be disabled!

2) SynAttack protection dynamically calculates the thresholds (of when it considers an attack has started) based on the number of CPU cores and memory available and hence it doesn’t expose any configurable parameters via registry, netsh etc.

[Philip]

Thanks Keight. You are generally correct (per the documentation), however it is often the case that older settings still work (and newer settings are broken) with MS.

This is not included in the TCP Optimizer for Windows 8/10/2012.