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FIREWALL.CX OSI MODEL

Examples of 
Windows 2000 & XP Registry Settings1

the Regentry.chm file, included in the Windows 2000 and Windows XP resource Kits
is the ultimate resource for Registry information.
 

ArpCacheLife Registry Setting (Windows 2K & XP default to 120 seconds):

Registry Information Details
Location HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters
Data type REG_DWORD
Valid range 0-0xFFFFFFFF
Default value 120
Present by Default No

 

ArpUseEtherSNAP Registry Setting  Must be set to 1 to enable use of the Ethernet 802.2 SNAP frame format for
IP and ART traffic over Ethernet.

Registry Information Details
Location HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters
Data type REG_DWORD
Valid Range 0-1 (0=false or off; 1=true or on)
Default Value 0
Present by default No

 

DefaultTTL Registry Setting    You can set the default TTL for a host using the DefaultTTL Registry setting.  You can
set the default TTL for a host using the DefaultTOS Registry setting. The entry is set in decimal for the entire TOS field

Registry Information Details
Location HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters
Data type REG_DWORD
Valid Range 1-255
Default Value 128
Present by default No

 

DefaultTOS Registry Setting the Registry  You can set the default TTL for a host using the DefaultTOS Registry setting.
The entry is set in decimal for the entire TOS field.

Registry Information Details
Location HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters
Data type REG_DWORD
Valid Range 0-255
Default Value 0
Present by default No

 

EnablePMTUDiscovery Registry Setting disable PMTUDiscovery by setting to 0

Registry Information Details
Location HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters
Data type REG_DWORD
Valid Range 0 or 1
Default Value 1
Present by default No

 

EnablePMTUBHDetect Registry Setting Defines whether the host should detect black hole routers.  A black hole router silently discards
packets without indicating the cause, thereby thwarting any auto-recovery or auto-reconfiguration attempts. Many administrators
disable ICMP responding for security reasons.

Registry Information Details
Location HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters
Data type REG_DWORD
Valid Range 0 or 1
Default Value 0
Present by default No

 

PerformRouterDiscovery Registry Setting   Setting to 0 disables the ICMP Router Discovery Process..

Registry Information Details
Location HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\Interfaces\<interface>
Data type REG_DWORD
Valid Range 0-1 (0=false or off; 1=true or on)
Default Value 0
Present by default No

 

PerformRouterDiscovery Registry Setting   Setting to 0 disables the ICMP Router Discovery Process..

Registry Information Details
Location HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\Interfaces\<interface>
Data type REG_DWORD
Valid Range 0-1 (0=false or off; 1=true or on)
Default Value 0
Present by default No

 

MaxUser Port Registry Setting   You can increase the supported maximum user port number by adding MaxUserPort
Registry entry.

Registry Information Details
Location HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters
Data type REG_DWORD
Valid Range 5000-65534
Default Value 5000 ports
Present by default No

 

TcpMaxConnectionRetransmissions Registry Setting   Defines the number of SYN retries sent when attempting (p229)
to establish a TCP connection.

Registry Information Details
Location HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters
Data type REG_DWORD
Valid Range 0-255
Default Value 2 retransmissions
Present by default No

 

TcpNumCorrections Registry Settings   Defines the number of TCP connections that can be open at one time (p229)

Registry Information Details
Location HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters
Data type REG_DWORD
Valid Range 0-0xFFFFFE
Default Value 0xFFFFFE (16,777,214) connections
Present by default No

 

KeepAliveTime Registry Settings  Defines how long to wait before sending the first TCP keep-alive packet. (p231)

Registry Information Details
Location HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters
Data type REG_DWORD
Valid Range 0-0xFFFFFE
Default Value 0x6DDD00 (7,200,000) milliseconds
Present by default No

 

KeepAliveInterval Registry Setting   Defines the delay between keep-alive retransmissions when no acknowledgments are recieved (p232)

Registry Information Details
Location HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters
Data type REG_DWORD
Valid Range 0-0xFFFFFFFF
Default Value 0x3E8 (1000) milliseconds
Present by default No

 

TcpTimedWaitDelay Registry Setting   You can control the Time Wait delay by changing this setting (p234)

Registry Information Details
Location HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters
Data type REG_DWORD
Valid Range 30-300
Default Value 0xF0 (240) seconds
Present by default No

 

TcpMaxDataRetransmissions Registry Setting (p236)

Registry Information Details
Location HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters
Data type REG_DWORD
Valid Range 0-0xFFFFFFFF
Default Value 5 retransmissions
Present by default No

 

TcpInitialRTT Registry Setting  Defines the initial retransmission timeout (RTO). (p237)

Registry Information Details
Location HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters
Data type REG_DWORD
Valid Range 0-0xFFFF (seconds)
Default Value 3 seconds
Present by default No

 

GlobalMaxTcpWindowSize Registry Setting  (see, TcpWindowSize Setting) (p239)

Registry Information Details
Location HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters
Data type REG_DWORD
Valid Range 0-0x3FFFFFFF (bytes)
Default Value 0x4000 (16,384 bytes)
Present by default No

 

TcpWindowSize Registry Setting  This setting, if existent, overrides the GlobalMaxTcpWindowSize Registry setting for the interface
on which it is configured. (p240) Used  to determine the amount of unacknowledged data that can go out on the wire from any sender.

Registry Information Details
Location HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\Interface\interfacename
Data type REG_DWORD
Valid Range 0-0x3FFFFFFF (bytes)
Default Value 0xFFFF (the lesser of 17,520 for Ethernet, 65,535 bytes for other networks, or GlobalMaxTcpWindowSize; see regentry.chm file for other exceptions)
Present by default No

 

TcpUseRFC1122UrgentPointer Registry Setting  Can be configured to interpret the Urgent Pointer field according to RFC1122 p244)
This setting is relevant only if  the URG pointer is set.  If the URG pointer is set, the receiver must examine this filed to see where to
 look/read first in the packet. Win 2K and XP are default configured to use the Urgent Pointer filed interpretation defined in RFC 793.
This Registry setting will change the Win2K and XP default of RFC 793 to RFC1122 settings.  (0=false or off; 1=true or on)

Registry Information Details
Location HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters
Data type REG_DWORD
Valid Range 0-1
Default Value 0
Present by default No

 

EnableProxy Registry Setting  Entry must be  set to 1 to configure any Win 2K or XP workstation or server to be a WINS proxy.

Registry Information Details
Location HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\NetBT\Parameters
Data type REG_DWORD
Valid Range 0-1 (0=false or off; 1=true or on)
Default Value 0
Present by default No


1. Guide to TCP/IP, second edition, Laura A Chappell, Ed. Tittel, Thompson Course Technology, 2004
 

Uniques by CatheyMc