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Win2k server not allowing wireless network entry

I have two Cisco Aironet wireless access points. They are connected to the network by network cables. Everything was just great until about six months ago, when my Windows 2000 server (not using Active Directory) stopped letting anyone access it wirelessly. It just says you don't have permission. You never get to the point of being able to enter a user name and password for security to access the folders like for the other servers. Those same users have no problem accessing that server when connected by cable to the network. I thought maybe a patch got installed on the server for Windows 2000 that caused this. But I can't find out what happened. I have had a few people out here to look at the situation to no avail. Everyone is scratching their heads, especially me. Please help!

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This sounds like your Cisco AP is not relaying NetBIOS traffic between your wireless to wired network. Have you checked the Protocol Filters configuration on your Cisco Aironet APs? You don't want to filter IP Protocols required by NetBIOS (137-139) or NetBUI (if your stations are sending NetBUI rather than NetBIOS over TCP). You don't mention if you're using VLANs, but if wireless traffic is being directed into one VLAN and your Windows 2000 server is in another VLAN, LAN broadcasts may not make it from one VLAN to the other. Check your Cisco Aironet VLAN setup.

To further diagnose this problem, I'd use a LAN analyzer to capture traffic on both the wireless and wired links. By comparing traffic on both sides of the AP, you can see whether some traffic is being blocked. You may also be able to see error messages carried in NetBIOS traffic if packets are not being blocked but rejected by your Windows 2000 server. Use nbtstat and net commands on your wireless station to easily generate NetBIOS when capturing traffic.


Member feedback:
I am neither using VLAN, nor am I filtering any protocols. A suggestion was made that maybe the built-in network card on the server was the problem and that I should try installing a separate card and using that one. I don't see how the card can allow some network traffic and not other traffic coming from a wireless access point that is hard wired to the network. Do you?


Lisa's response:
No, I don't think the server's network card is likely to be the problem, since arriving traffic in both cases is carried by standard 802.3 Ethernet, and your existing server hardware worked fine until a few months ago. If you've ruled out the access point's configuration as the culprit, you should suspect the server's network settings, starting with a detailed comparison of packets captured during both successful and unsuccessful NetBIOS requests.

This was first published in July 2004

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