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Registry tweaks, tricks & hacks to optimize, enhance and secure Microsoft Windows.

Disables DHCP Router Discovery (All Windows)
Category: Home > Security > Network

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The ICMP Router Discovery Protocol (IRDP) comes enabled by default for Windows clients using DHCP. This can be a security issue because by spoofing IRDP Router Advertisements, an attacker can remotely add default route entries on a remote system.

Open your registry and find the key below for your operating system.

Windows 95, 98 and Me
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Class\NetTrans\####]

Where #### is the protocol binding for TCP/IP. More than one TCP/IP binding may exist.

Windows NT, 2000 and XP [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters]

Create a new DWORD value called "PerformRouterDiscovery" and set the value to equal "0" to disable router discovery.

Restart Windows for the change to take effect.

Note: It is recommended that you disable this value as it is a possible security flaw in the DHCP service.

Registry Editor Example
|NameTypeData|
|(Default)REG_SZ(value not set)|
|PerformRouterDiscoveryREG_DWORD0x00000000 (0)|
-
|HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters|
-

Settings:
System Key: [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters]
Name: PerformRouterDiscovery
Type: REG_DWORD (DWORD Value)
Value: (0 = disabled, 1 = enabled)

Disclaimer: Modifying the registry can cause serious problems that may require you to reinstall your operating system. We cannot guarantee that problems resulting from modifications to the registry can be solved. Use the information provided at your own risk.

Last Modified: December 19, 2002

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