Become aware of automatic routes update

[Stefan Mayr]

Hello,

in our office we have one windows 2000 server (sp4) which autoupdates
its routing tables. It adds and deletes routes so specific client
IP-addresses.

Server: 192.168.0.4/24 Gateway: 192.168.0.1
Client: 192.168.1.23/24 Gateway: 192.168.1.1

After some connections the server would add and delete the following
route:

192.168.1.23 Mask 255.255.255.255 Gateway 192.168.0.1
although the default route 0.0.0.0 mask 0.0.0.0 gw 192.168.0.1 is set
correctly

any ideas where to disable this "feature"? The problem is, that
sometimes the server seems to loose the routes for 0.0.0.0 and
192.168.0.0.

 

[Marc Reynolds [MSFT]]

Probably due to ICMP redirects. You can stop Windows 2000 from creating host
routes based on ICMP redirects as noted below, but you should also
investigate why the router is sending a ICMP redirect in the first place.


Windows 2000 can disable ICMP redirects by changing the value of the
EnableICMPRedirect value in the following registry key:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters

The default value of 1 enables ICMP redirects, and 0 disables ICMP
redirects. Modifying this registry value to 0 should prevent the creation of
host routes when an ICMP redirect packet is received. However, changes to
the value of this key have no effect on ICMP redirects.


--

Thanks,
Marc Reynolds
Microsoft Technical Support

This posting is provided "AS IS" with no warranties, and confers no rights.

 

[Stefan Mayr]

Thanks, this registry switch did it. I just don't understand why our
other servers are not concerned. There is no option for our layer 3
switch to disable ICMP redirects, so all should be affected.