ICS oddity

[steve]

I have win2000 server on a small LAN. Static IP's, not using DHCP. One
of the clients (winxp) has ICS, using dial-up modem.

Everything works, but for some reason whenever any client computer is
turned on, and *many* times a day for whatever reason, the ICS host
will start dialling-up to internet.

If I'm setting at the winxp-ICS-host machine, and cancel the dial-up,
it will try again immedialty at least 4 times, sometimes more. Also,
once in while, but not always, after cancelling the dial-ups, a dialog
box will pop up, saying something like "A computer or a program needs
information from Server1, which connection do you want to use?" and it
only lists the dial-up connection.

On all clients, I have static ip, gateway of the ICS Host, and DNS of
the Server1 only (don't have secondary DNS)

I have forwarders enabled on the Server, with my ISP's DNS there.
Don't have a "." root zone.

Everything is working, but something must be wrong, since the ICS host
is always dialing up.

I Used ICS without this constant dialing out, it only started after
upgrading from NT4 server to win2000 with AD.

Side note, I set up a different small site, almost identical to this
one, win2000 server, ICS Host is a winxp machine. They never have the
ICS host computer dialing out without someone starting it themselves.

I'm overlooking something, but don't know what.

Any suggestions? Thanks
Steve

 

[Steven L Umbach]

I am not an ICS user but in an AD domain a W2K/XP Pro computer will access dns during
the startup process. If they are configured to use the ISP dns server and not the AD
domain controller only, that may be triggering the dial up. I suppose Windows Update
could do the same. You might try to use Ethereal packet sniffer on the XP ICS box to
capture some traffic coming in to the internal interface to see if can determine what
the trigger is. --- Steve

http://www.ethereal.com/

 

[john smit]

I downloaded and installed ethereal. When I have the modem unplugged (but
ICS is always trying to dial-up), it shows:
(server: 192.168.0.2 ICS host: 192.168.0.1)

Source: 192.168.0.2 Destination: ISP'sDNS Server's IP DNS
Standard query PTR.....1.0.168.192.in-addr.arpa
Source: 192.168.0.2 Destination: ISP'sDNS Server's IP DNS
Standard query PTR.....2.0.168.192.in-addr.arpa
Source: 192.168.0.1 Destination: 192.168.0.2 DNS
Standard query PTR.....ISP'DNS_IP...in-addr.arpa

some variations on that, over and over

Thanks, Steve

 

[Steven L Umbach]

Hi John.

It looks like your domain computers are trying to register/update/query their reverse
zone IP records on the ISP dns server which would cause what you are experiencing.
Make sure that all your domain computers point only to the domain controller as their
preferred dns server and that the domain controller points only to itself as it's
preferred dns server in tcp/ip properties. Using ICS dialup for a W2K domain is
highly unusual and not recommended and may never work right. A W2K domain usually
uses an internal dhcp server [which does more than just hand out IP addresses] and
that will not work well with ICS. If ICS is handling your IP address allocation you
will have to manually configure your domain computers with the dns address of the
domain controller and the domain controller must have a static IP address and
configuration. I really don't know how ICS will handle internet dns name resolution
in a situation like yours. Normally a domain computer sends ALL dns name resolution
requests to the domain controller running dns and it either forwards internet name
resolution requests to your ISP dns server or actually goes out to the internet root
servers and resolves names with their help. However the ICS acts as a dns proxy for
clients as traffic is sent to it on it's lan interface which is their gateway.
Normally in a W2K domain environment, internet access is provided through a nat
router or enabling rras on a W2K server and enabling NAT on it though I don't know if
their is any way to set it up for demand dial internet access for lan users, but see
the first link below for one possibility to look at. --- Steve

http://techrepublic.com.com/5100-6263-1033065-1.html
http://www.winntmag.com/Articles/Index.cfm?ArticleID=7187 -- explains dynamic dns
http://www.microsoft.com/windows200...000/en/professional/help/HowTo_share_conn.htm
http://tinyurl.com/2p58j -- same link as above, shorter. -- see warning about using
in a domain