I seem to have broken my ICS

#1 Bursar

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Posts: 672
Joined: 04-May 00

Posted 19 October 2003 - 05:11 PM

I'm not sure exactly what's gone wrong, but here's the story, so maybe someone can help out.

I had a PC running WinXP with 2 network cards. One was hooked up to my cable modem, the other was connected to a switch into which another machine was connected. The cable modem was connected to a 3COM PCI card, and the LAN was run from the onboard NIC.

The cable modem NIC was set to DHCP, and the LAN NIC was as follows:

IP: 192.168.0.1
SN: 255.255.255.0
GW: <blank>
DNS: <blank>

The client machines was configured as follows:

IP: 192.168.0.2
SN: 255.255.255.0
GW: 192.168.0.1
DNS: 192.168.0.1

This all worked perfectly.

Over the past few days, I dismanted that PC and rebuilt it (new mobo, RAM, hard disk and so-on).

I reinstalled XP, installed all the patches and got the Internet up and working. I then came to look at the LAN, and I cannot get it working for the life of me.

The new motherboard in the 'server' machine has an onboard Realtek NIC, and it seems to be working OK. I have configured as above.

The client machine hasn't changed in anyway, but I can't get the PCs to talk to each other properly.

Pinging is very intermittent, and ICS just doesn't work at all. I don't think I've missed anything obvious, but if I have, I'd love to know what it is.

In the meantime, I'm going back to pulling my hair out.

Please save me before I'm completely bald....

#2 Bursar

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Group: Members
Posts: 672
Joined: 04-May 00

Posted 19 October 2003 - 09:46 PM

I've done some more tests, and here's what I have now...

PC1 (server) WinXP - all patches - 192.168.0.1
PC2 (client) Win2K - almost all patches - 192.168.0.2
PC3 (client) WinXP - no patches - 192.168.0.3

PC1 can now ping PC2 and PC3.

PC2 can ping PC3 but not PC1.

PC3 can ping PC2 but not PC1.

I've enabled logging on PC1, and here what I get. Hopefully the formatting hasn't gotten too mangled:

Code:

date time action protocol src-ip dst-ip src-port dst-port size tcpflags tcpsyn tcpack tcpwin icmptype icmpcode info
2003-10-19 19&#58;41&#58;22 DROP UDP 192.168.0.1 239.255.255.250 1900 1900 436 - - - - - - -
2003-10-19 19&#58;41&#58;22 DROP UDP 192.168.0.1 239.255.255.250 1900 1900 442 - - - - - - -
2003-10-19 19&#58;42&#58;15 DROP UDP 192.168.0.2 192.168.0.1 1042 53 62 - - - - - - -
2003-10-19 19&#58;42&#58;16 DROP UDP 192.168.0.2 192.168.0.1 1042 53 62 - - - - - - -
2003-10-19 19&#58;42&#58;18 DROP UDP 192.168.0.2 192.168.0.1 1042 53 62 - - - - - - -
2003-10-19 19&#58;42&#58;20 DROP UDP 192.168.0.2 192.168.0.1 1042 53 62 - - - - - - -
2003-10-19 19&#58;42&#58;24 DROP UDP 192.168.0.2 192.168.0.1 1042 53 62 - - - - - - -
2003-10-19 19&#58;42&#58;32 DROP UDP 192.168.0.2 192.168.0.1 1043 53 68 - - - - - - -
2003-10-19 19&#58;42&#58;33 DROP UDP 192.168.0.2 192.168.0.1 1043 53 68 - - - - - - -
2003-10-19 19&#58;42&#58;34 DROP UDP 192.168.0.2 192.168.0.1 1043 53 68 - - - - - - -

The first two entries are pings, the others are requests for a web page. So for some reason my machine is just dropping the incoming requests from my LAN. I'm a bit stumped about what to do...