Sentech and ICS

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KickTheBucket

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Guys, i got a prob...

I've got a client with a Sentech connection. They've got a USB modem and need to get 3 pc's onto the net. The Host machine (machine with the modem connected to it) is running WinXp Pro and the other 2 pc's are running XP Home.
I've set up a normal network with the host pc as the DHCP server and with Internet Connection Sharing. All 3 machines can communicate with each other. The problem is that the 2 XP home machines cannot open some sites. For example, all 3 machines can open www.yahoo.com, but only the host machine can open mail.yahoo.com (or the link to Yahoo Mail). I don't get the "This page cannot be displayed" error, it just never opens. The host machine can access any page it would seem.

I can ping mail.yahoo.co.za from any machine with request time outs every 15 or so packets, which i'm guessing is fairly normal for sentech. I've never really worked with sentech before but assumed that it's a similar concept to ADSL.

I've disabled windows firewall on all the machines just in case it was that which was causing the hang up. Still no joy. I've also taken each of the 2 XP Home pc's back to work and hooked them up to my network, running ADSL off a router, and they have no problem opening any site.

I've also tried entering 196.38.110.2 and .2 (off the sentech site) into the DNS of the TCP/IP configuration of the XP Home machines, and no luck.

PPLLEEEAASSSEEE could someone help me... i'm about to throw all 3 pc's into the pool!! :D
 
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Very interesting. How about individual Anti-Virus packages, etc on the Home machines?

I wouldn't ever use Sentech's USB connection for internet sharing again. Had endless problems. R250 ethernet cable, R350 - R500 router, and all is sorted. But don't suppose it's an option at this stage?
 
The one machine has NAV '05 on it, and the other one doesn't have any anti-virus on it as far as i remember.
If the connection belonged to me, i'd get rid of the USB connection in a flash, but alas it's not...
Did you have the same probs as me, or different ones?
 
Sentech and ICS does indeed work. Your symtom indicates that your problem is definitely caused by the MTU settings on the client PC being too large (default is 1500). Anything that requests small packets gets throught, such as simple webpages and short pings. Complex pages that return large packets do not load. Solution: Change the MTU of the lan cards on all the PCs to 1458 using DrTCP.

The only problem I have had is with ZoneAlarm on the ICS gateway machine. I know you are not using ZA but this might help someone else. Firstly, you need to set ZA as an ICS/NAT Gateway (Firewall|Main|Advanced). V4 worked fine like this, but V5 has a problem, and I haven't upgraded to V6 yet so can't comment about V6. The ZA website also says that the free version cannot be an ICS/NAT gateway. The problem is that the clients cannot resolve names - seems they cannot get through to the DNS servers. The solution for this is to define the two DNS servers (66.18.68.1 & 66.18.65.1) as "Trusted" "IP Addresses" (Firewall|Zones).
 
Wow, thanks JAS!!!

If you're right, OMG!!!! I'm gonna buy you a virtual case of beer!!
 
I have the exact same setup although I use Xp Pro in all cases with ZA Pro as an ICS/NAT on the gateway machine.
Although I dont have any problems, should I also define the DNS servers JAS ?
 
Hi ProAsm. I have ZA Pro (purchased version) as an ICS/NAT Gateway on a Win2k (SP4) machine, with a USB MyWireless modem. The client PCs run Win98, Win2K, WinXP Home, WinXP Pro. BTW, ZA on the ICS machine protects the clients as well. Although you can install ZA on the client PCs, it isn't necessary to protect them from the outside.

ZA version 4 was happy just like that - no other special settings. When I upgraded to ZA version 5 I couldn't resolve names from any of the clients, although I could ping IP addresses, so I knew it had to have something to do with the name lookup. I tried varous different ZA settings, without success. There may be another solution, but the only way I could get arround it was to define the DNS servers as Trusted IP Addresses. I've been too scared to upgrade to ZA version 6 incase they have broken something else.

If your setup is working, then it would appear that the problem is not present for a ZA/WinXP Pro combination - It could be that the problem is limited to a ZA/Win2k Pro combination. If it is working, don't fix it!
 
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Originally my Gateway machine ran Win2k with Winroute Pro and that was rock solid but you need to be a rocket scientist to operate Winroute so I dumped it for ZA Pro.
Hell I ran into a zillion problems in that although the client PC's could access the Internet, they could not see each other or ping each other.
It was a friggin nightmare so I dumped the Win2k and put on Xp Pro and everything now works like a dream.
I also use ZA Personal on one client machine and that too works well.
All machines also use AVG with no problems.
 
I had this problem too, but after doing a SP2 update the problem cleared. Maybe SP2 sets the MTU differently ?
 
Yes SP2 is supposed to have a utility which automatically adjusts the MTU size or something like that. But I have seen machines running in WinXP SP2 also giving hassles. I have seen this problem quite regularly so check this first. DrTCP is a breeze to use as well. It can take many forms but anytime you have trouble with webpages loading, check DrTCP...
 
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