XP PPTP VPN IP Address

[Bob]

My client wants an XP PPTP VPN with the server at the office and the
client at home. I have advised him that he needs a static IP address
at the office (or else we will have to install dynamic DNS).

My question is about the VPN client at his home. Initially he will
connect the client machine directly to the cable modem. Later we will
install a router. We will set DHCP to obtain the IP address from his
cable ISP.

Does the IP address of the client at home need to be static for long
term stability? For example, if the Internet connection (cable)
changes its IP address while the client machine is connected to the
office VPN server, what will happen to the VPN connection? Will there
be a temporary interruption in the VPN connection or will the
connection be lost and have to be re-established manually? What
happens to the session if he is working when the IP address change
occurs? Will file transfers abort, etc? Is this even an issue for a
cable Internet connection?


--

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You know you are in Hell when you have to make a
distinction between what is moral and what is legal.

 

[Sharoon Shetty K [MSFT]]

If the IP changes when the user is connected, the PPTP connection would
require re-establishment from the VPN client.

---

Thanks
Sharoon
(e-mail address removed)


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

 

[Bob]

If the IP changes when the user is connected, the PPTP connection would
require re-establishment from the VPN client.

Is this also true with hardware VPNs like ZyWall? I would expect such
hardware to behave in a more civilized manner. However, there may be
an intrinsic problem with DHCP that prevents maintaining the
connection through an address change.

The bottom line is that I have to decide if we need static IPs for
both ends of the VPN no matter what equipment we use.


--

Map Of The Vast Right Wing Conspiracy:
http://www.freewebs.com/vrwc/

You know you are in Hell when you have to make a
distinction between what is moral and what is legal.

 

[ppointer]

Does the IP address of the client at home need to be static for long
term stability? For example, if the Internet connection (cable)
changes its IP address while the client machine is connected to the
office VPN server, what will happen to the VPN connection? Will there
be a temporary interruption in the VPN connection or will the
connection be lost and have to be re-established manually? What
happens to the session if he is working when the IP address change
occurs? Will file transfers abort, etc? Is this even an issue for a

I've never seen an IP address change while I've been connected from
home. Not to say it can't or won't happen, but I haven't seen it. None
of my "clients" have static IPs at their homes either, and they're
perfectly content with our PPTP VPN service.

 

[Bill Sanderson]

I'm with ppointer--I think it very unlikely that this will be an issue in
practice, unless your client runs very long sessions--24 hours or more, or
likes to work late at night.

I haven't looked at what happens with Cable ISP's but DSL ISP's don't appear
to interrupt a call in progress except perhaps once in 24 hours, and then it
seems to happen after Midnight--and I suspect this is intentional.

Fixed IP's may enable you to use IPSEC rather than PPTP, which is a
significant plus in terms of security.