Changing DHCP Ranges

[Guest]

Under Windows 98SE there was a relatively easy way to configure the DHCP
ranges for the DHCP server under Internet Connection Sharing through a series
of registry modifications. Is there a similar way to do this for Windows XP?
I have a situation where the upstream ISP is forcing a 192.168.0.X/24 IP
address down to the "internet" side of a WinXP Pro computer, and ICS trying
to force 192.168.0.1/24 onto the "lan" side of the same computer. Obviously
the computer is confused as to where to send packets when it has two adapters
configured to the same network.

Anyone know how to get around this (other than putting an additional router
between the XP box and the ISP)?

Thanks

 

[Steve Winograd [MVP]]

Under Windows 98SE there was a relatively easy way to configure the DHCP
ranges for the DHCP server under Internet Connection Sharing through a series
of registry modifications. Is there a similar way to do this for Windows XP?
I have a situation where the upstream ISP is forcing a 192.168.0.X/24 IP
address down to the "internet" side of a WinXP Pro computer, and ICS trying
to force 192.168.0.1/24 onto the "lan" side of the same computer. Obviously
the computer is confused as to where to send packets when it has two adapters
configured to the same network.

Anyone know how to get around this (other than putting an additional router
between the XP box and the ISP)?

Thanks

I'm sorry, but it isn't possible to change the ICS DHCP range in
Windows XP.

You can manually change the host's LAN connection IP address to a
different subnet (e.g. to 192.168.1.1) after enabling ICS. However:

1. It's not recommended, tested, or supported by Microsoft.

2. It will disable the host's DHCP server, requiring you to manually
configure the clients

3. There's no guarantee that your network will work properly if you
do.

If you want to try it, at your own risk, make a restore point with
System Restore first so that you can undo the change in case of
problems.
--
Best Wishes,
Steve Winograd, MS-MVP (Windows Networking)

Please post any reply as a follow-up message in the news group
for everyone to see. I'm sorry, but I don't answer questions
addressed directly to me in E-mail or news groups.

Microsoft Most Valuable Professional Program
http://mvp.support.microsoft.com

 

[Guest]

Steve, that is fine, but then can you direct the masses to a workaround,
even like an extreme of changing DLLs with a hex editor? This is a huge
limitation and people are not really keen to change their IP infrasturcture
just because of this.

Thanks

 

[Guest]

OK, I found a solution, but beware it may violate licence agreement with MS
and as said changing the address means no support for it if you have
problems. This is what to do:

1. Make backup copies of WINDOWS\system32\ipnathlp.dll and hnetcg.dll
2. With a hex editor find C0 A8 00 01 in both files and replace it with
the default IP of your preference in both files (make sure they're the same
in both files) - C0 A8 00 01 is hexa for 192 168 0 1
3. May be optional - Set the DNS server IPs of your network card which is
the one being bridged (not the one which is sharing the connection, but the
one with which it is shared); I did not test with not setting it; Windows
logs an event log entry of DNS proxy not being able to read the DNS settings
from Registry, but it works anyway
4. Update files in WINDOWS\ServicePackFiles\i386
5. This step must be done via recovery console or from another Windows
instance that can access the hard drive directly because Windows is locking
hnetcfg even in safe mode: replace the original files with the modified ones
6. Reboot and be happy ever after