RE: Change IP Address of VPN
- From: "William Robertson" <robertson.william@xxxxxxxxxxxxxx>
- To: "'[ISAserver.org Discussion List]'" <isalist@xxxxxxxxxxxxx>
- Date: Wed, 2 Jul 2003 10:41:07 +0200
Hi Tom
I?m with you on the bottom line of not being able to control the source
address for outbound communications, but what about the reverse,
controlling the inbound address.
For example, if I can get my inbound VPN clients to connect to the 3rd
IP Address, surely all communications will then leave ISA on this 3rd IP
and not the 1st one which is used by all other communication?
This should then in principle be a way in which I can ?control? the
source address of the VPN connection?
So I have changed the 2 Packet Filter rules to be applied to this 3rd
address, but I?m hoping you can assist in getting RRAS to accept the
connection on this 3rd IP Address because so far all my efforts have
failed.
Cheers
William R.
-----Original Message-----
From: Thomas W Shinder [mailto:tshinder@xxxxxxxxxxxxxxxxxx]
Sent: 02 July 2003 09:57 AM
To: [ISAserver.org Discussion List]
Subject: [isalist] RE: Change IP Address of VPN
http://www.ISAserver.org
Hi William,
I would not make that assumption because I have no idea how ISA decides
what address to use for the source address for outbound communications.
I once heard a pretty eloquent explanation from Jim regarding this, but
I don't recall the details, and I wasn't smart enough at the time to
fully appreciate what the issue was. However, I'm a bottom line kind of
guy and I did appreciate the fact that you can not control the source
address for any particuarl outbound packet.
And that's what counts, right?
HTH,
Tom
Thomas W Shinder
<http://www.isaserver.org/shinder> www.isaserver.org/shinder
ISA Server and Beyond: http://tinyurl.com/1jq1
Configuring ISA Server: <http://tinyurl.com/1llp>
http://tinyurl.com/1llp
-----Original Message-----
From: William Robertson [mailto:robertson.william@xxxxxxxxxxxxxx]
Sent: Wednesday, July 02, 2003 2:54 AM
To: [ISAserver.org Discussion List]
Subject: [isalist] RE: Change IP Address of VPN
http://www.ISAserver.org
Aaah Tom, you leave me with no hope?. :-(
Do I at least have it correct that the VPN/RRAS connection appears to be
restricting access to that External IP because that IP is now involved
in some form of secure communications?
Also, do you think I need to investigate this as an RRAS or an ISA
issue?
Thanks
William R.
-----Original Message-----
From: Thomas W Shinder [mailto:tshinder@xxxxxxxxxxxxxxxxxx]
Sent: 02 July 2003 08:36 AM
To: [ISAserver.org Discussion List]
Subject: [isalist] RE: Change IP Address of VPN
http://www.ISAserver.org
Hi William,
OK, I now understand your problem. However, I do not understand the
solution :-)
The conventional wisdom is that all outbound communcations leave with a
source address that is the primary address on the external interface of
the ISA Server. However, as you've discovered, that is not true. That
fact is, there is no documentation as to what changes the source address
to change from the primary address to one of the secondary addresses. I
suspect its related to VPN, but since I really have no idea as to what's
going on, it could be anything.
Since there is no way to bind a particular service to a particular port
for outbound access, you can't depend on a particular address of the
external interface to be used as an identifier by a remote host. You can
provide the range, but forget out used a single address on the external
interface as an authenticator.
HTH,
Tom
Thomas W Shinder
<http://www.isaserver.org/shinder> www.isaserver.org/shinder
ISA Server and Beyond: http://tinyurl.com/1jq1
Configuring ISA Server: <http://tinyurl.com/1llp>
http://tinyurl.com/1llp
-----Original Message-----
From: William Robertson [mailto:robertson.william@xxxxxxxxxxxxxx]
Sent: Wednesday, July 02, 2003 1:24 AM
To: [ISAserver.org Discussion List]
Subject: [isalist] RE: Change IP Address of VPN
http://www.ISAserver.org
Hi Tom
Don?t know if I understand. Are you asking whether a new resource record
for my ISA?s external IPis created in my DNS once a VPN client has
connected? If so, I will check shortly?
As for the clients unable to connect, I mentioned earlier that the
problem is that RRAS seems to secure the external IP Address upon which
the VPN has been established (well, that?s my naïve understanding so
far) and this then prohibits any other non-VPN connection to then leave
ISA on that same IP Address. So ISA then decides to route all other
traffic (such as my SAP/R3 traffic) through one of the other 2 IP
Addresses, and the reason then why my connection fails is because the
?receiving? firewall for my SAP/R3 connection doesn?t permit that
specific IP Address. It is configured to only allow the first address,
and none others.
Now I know that I can fix this by telling my parent company to accept my
full range of addresses, but I am concerned for future problems arising
from a similar scenario.
That is why I wish to change the IP Address that VPN clients use to
connect to my ISA Server (I wish to use the last of the 3 addresses and
?dedicate? it to VPN connections only) so that all the other (normal)
traffic goes through the first IP Address, as it currently does, and
then all inbound VPN?s are established on the last IP Address.
Your comments?
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