PPTP VPN Classful Routing

  • Thread starter Thread starter BH
  • Start date Start date
B

BH

The situation is that I created a PPTP VPN connection to a datacenter
environment using class A IP addresses. After creating this connection,
I wanted to maintain Internet access, so I unchecked the advanced TCP/IP
flag to use the remote default gateway. However, since Windows does not
ask for a network and mask for the VPN connection it defaults to
classful routing.

So, as an example, I connect to VPN concentrator 10.1.0.1 and I only
want traffic to the 10.1.0.1/24 network to go through VPN. Everything
else I want to use my current default gateway. Windows, however, has
another idea in mind and simply adds a route to 10.0.0.0/8 through the
VPN. So what I want is all traffic to 10.1.0.0-10.1.255.255 to go
through the VPN, but Windows gives me 10.0.0.0-10.255.255.255.

I know I can manually modify the routes by removing the ones created for
the VPN and injecting new ones, but this is annoying. I am hoping that
someone has a more graceful solution in mind I could try.

Thank you,

BH
 
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--------------------
| Date: Wed, 10 Aug 2005 16:16:26 -0500
| From: BH <[email protected]>
| Reply-To: (e-mail address removed)
| User-Agent: Mozilla Thunderbird 1.0 (Windows/20041206)
| X-Accept-Language: en-us, en
| MIME-Version: 1.0
| Subject: PPTP VPN Classful Routing
| Content-Type: text/plain; charset=ISO-8859-1; format=flowed
| Content-Transfer-Encoding: 7bit
| Message-ID: <#[email protected]>
| Newsgroups: microsoft.public.windowsxp.work_remotely
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| Path: TK2MSFTNGXA01.phx.gbl!TK2MSFTNGP08.phx.gbl!TK2MSFTNGP15.phx.gbl
| Xref: TK2MSFTNGXA01.phx.gbl microsoft.public.windowsxp.work_remotely:12753
| X-Tomcat-NG: microsoft.public.windowsxp.work_remotely
|
| The situation is that I created a PPTP VPN connection to a datacenter
| environment using class A IP addresses. After creating this connection,
| I wanted to maintain Internet access, so I unchecked the advanced TCP/IP
| flag to use the remote default gateway. However, since Windows does not
| ask for a network and mask for the VPN connection it defaults to
| classful routing.
|
| So, as an example, I connect to VPN concentrator 10.1.0.1 and I only
| want traffic to the 10.1.0.1/24 network to go through VPN. Everything
| else I want to use my current default gateway. Windows, however, has
| another idea in mind and simply adds a route to 10.0.0.0/8 through the
| VPN. So what I want is all traffic to 10.1.0.0-10.1.255.255 to go
| through the VPN, but Windows gives me 10.0.0.0-10.255.255.255.
|
| I know I can manually modify the routes by removing the ones created for
| the VPN and injecting new ones, but this is annoying. I am hoping that
| someone has a more graceful solution in mind I could try.
|
| Thank you,
|
| BH
|
 
I 've been all through this. It's to do with IPCP and RAS subnet masks.
If you look at your vpn clients subnet mask while connected it is
255.255.255.255. this is by defaul and cannot be changed. (when using
default gateway on remote network)

If you choose not to use the default gatewy on remote network, then you can
only router to the 254 hosts on teh same classefull subnet as you, even if
the correct IP settings are on the ISA Server.
It's shit, but this is by design..

google for IPCP DHCP RAS and you will find answers.

OJ
 
OJ said:
I 've been all through this. It's to do with IPCP and RAS subnet masks.
If you look at your vpn clients subnet mask while connected it is
255.255.255.255. this is by defaul and cannot be changed. (when using
default gateway on remote network)

If you choose not to use the default gatewy on remote network, then you can
only router to the 254 hosts on teh same classefull subnet as you, even if
the correct IP settings are on the ISA Server.
It's shit, but this is by design..

google for IPCP DHCP RAS and you will find answers.

OJ
Click to expand...

What a PITA, I guess I will have to look at some other options. Thank
you for the help.

BH
 
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