VPN assigns DNS and WINS servers

  • Thread starter Thread starter John
  • Start date Start date
J

John

When I use the standard Microsoft VPN client to connect to
my company's VPN server, it assigns the company's DNS
servers and WINS servers to me even though I have "Obtain
DNS server address automatically" unchecked and have
specified my ISP's DNS server address instead. An IPCONFIG
display shows the company's DNS servers and WINS servers
in the PPP adapter along with the DNS server that I
manually specified. The company's DNS servers are listed
ahead of mine. How do I prevent the VPN client from
assigning the DNS and WINS servers?
 
There are two steps to this process. The "Obtain DNS ... " box refers to
the initial connection. If set, this gets the DNS address from the RRAS
server as part of the PPTP negotiation.

After the connection is complete, the remote client can send a
DHCPINFORM message to the RRAS server which is relayed to the company DHCP
server (which would overwrite the values obtained from RRAS). This will be
where the extra addresses come from. Not sure how you can turn it off.
 
After the connection is complete, the remote client can send a
DHCPINFORM message to the RRAS server which is relayed to the company DHCP
server (which would overwrite the values obtained from RRAS). This will be
where the extra addresses come from. Not sure how you can turn it off.
Click to expand...

I thought the options settings (like WINS and DNS servers)
only come from the DHCP server IF the RRAS server is
a Relay Agent?

Of course if it IS A RELAY Agent this jibes perfectly with
what you wrote.
 
As I understand it, the DHCP relay agent is only required if the DHCP
server is not on the same segment as the RRAS server.

If they are on the same segment, the dhcpinform message id just put on
the LAN segment. If it is on a different segment, the DHCP relay agent sends
it on directed to the DHCP server's IP address.
 
Bill Grant said:
As I understand it, the DHCP relay agent is only required if the DHCP
server is not on the same segment as the RRAS server.
Click to expand...

No, there is a special weirdness about RRAS and DHCP.

If the RRAS server is NOT a "relay agent" then it returns
address/mask from the DHCP serve3r BUT its OWN
"options" (or the equivalent of options, default gateway,
WINS server, etc.)

If the RRAS server is a Relay Agent it returns the options
from the DHCP server.

Non-intuitive oddity of RRAS and DHCP.
If they are on the same segment, the dhcpinform message id just put on
the LAN segment. If it is on a different segment, the DHCP relay agent sends
it on directed to the DHCP server's IP address.
Click to expand...

The above is separate from the DHCP Relay Agent's normal
-- and obvious -- purpose.
 
Very interesting. Thanks, Herb.

Herb Martin said:
No, there is a special weirdness about RRAS and DHCP.

If the RRAS server is NOT a "relay agent" then it returns
address/mask from the DHCP serve3r BUT its OWN
"options" (or the equivalent of options, default gateway,
WINS server, etc.)

If the RRAS server is a Relay Agent it returns the options
from the DHCP server.

Non-intuitive oddity of RRAS and DHCP.


The above is separate from the DHCP Relay Agent's normal
-- and obvious -- purpose.
Click to expand...
 
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