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PCs call Remote Server via ISDN dial up

By araine ·
Windows 2000 PCs (SP3) call the Head office Servers seemingly of their own accord several times an hour, even at login prompt.
They connect to an ISDN router via a hub.
The 3 servers are running Win2K (latest service packs) also and are 2 controllers and an Exchange file/print server.
PCs - Netbios is disabled over TCP/IP, as is 'Register this connections settings in DNS'.
The Microsoft auto-update service is turned off.
The PCs work locally and/or connect the network domain to pick up email etc.
Tel bills are subsequently high, even though PCs are turned off at night.
The rogue calls seem to be using protocols 1 or 17
(ICMP or UDP).
How can I stop these calls please?

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PCs call Remote Server via ISDN dial up

by Matt Duggan In reply to PCs call Remote Server vi ...

DNS queries to servers on the other side of this ISDN might be causing it to dial. Your server will try to talk to other domain controllers around the network periodically to get replication events - this will generate DNS query traffic, followed byLDAP traffic.

It is not actually possible to keep a DC behind a dial-on-demand router, and expect it not to dial. This is a result of all Domain Controllers doing their best to keep in sync with the rest of the domain.


Sorry I can't make them stop, but it's just the way Active Directory works.

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PCs call Remote Server via ISDN dial up

by Matt Duggan In reply to PCs call Remote Server vi ...

The UDP traffic will most likely be a DNS lookup from the machine. I can't think off the top of my head what the ICMP would be, other than the dead obvious ping to see if the remote DC's are available.

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PCs call Remote Server via ISDN dial up

by hughesm1 In reply to PCs call Remote Server vi ...

Try running an anti-trojan program on your systems. I recommend this one which can be found at download.com: http://download.com.com/3000-2239-101**193.html?tag=lst-0-1 or at anti-trojan.net It comes with a free 15 day trial.

I also recommend running ZoneAlarm on your machines if you already aren't. It's an excellent firewall program and you can configure it to allow your computer to operate in "stealth mode" where outside requests to your machine will be blocked.

Also, check your settings as to how often your machines are configured to dial up to check e-mail. Perhaps they are set to automatically check every hour or two, thus the high number of calls placed.

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PCs call Remote Server via ISDN dial up

by rnwindahl In reply to PCs call Remote Server vi ...

I've had to set my ISDN modem to dial manually only. My setup used the browser to talk to the modem and I added the tcp/ip number to my favorites so it was easy to get to. Then set it for a 10 to 15 minute timeout or simply maunually disconnect whenyour done.

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PCs call Remote Server via ISDN dial up

by araine In reply to PCs call Remote Server vi ...

Thanks Gents for your replies. At the remote site I am running 2 PC clients - no servers/DCs there. I can understand the need for the 2 sites to know of each other's existence but is there any way to reduce the no. of these calls from the 12 or so every hour (obviously they are turned off at night)?
I have also put our servers details in the hosts and lmhosts file and have run a check for trojans.
The PCs have no settings for auto dialling (that I'm aware of) as they're 2 Win2K clients set upthe same as the local clients on the head office network. They connect via an Alchemy CyberGear Gold router which is configured not to dial automatically. It's the UDP, ICMP calls which are bringing the router up. I've also noticed TCP calls to port445 (SMB) and am wondering whether I can/should turn off File and Print sharing?

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