Red cross icon and wired cardÂ’s MAC address disabled possibility

[zillah]

I have got win2003 server laptop with 2 NIC cards :
1- Wired ( Broadcom 570x Gigabit Integrated Controller)
2- Wireless (Dell Wireless WLAN 1450 Dual Band WLAN Mini-PCI Card)

At work (not at home) when I plugged the internet cable (I tried more than one cable, because I though the problem with the cable itself) to wired card , I still can see there is a red cross is being displayed on top of the icon

I tried more than one wall jack socket still with different cables (of course I am using the right cable straight through), I still can see there is a red cross is being displayed on top of the icon,,,,


Definitely all cables and all wall jack sockets are working because when I tried the same cable and the same wall jack socket on other PCs, they work.

The test that I did were :

i- I did test to check the wired card, I connected my laptop and another PC directly by using cross over cable, it worked (i.e. there is no red cross).

ii- I tried to assign static ip address at work (not home) still the same problem is going on.

iii- I did another test At home I tried to use the wired card (normally I used wireless card) , I have got no problem , (i.e when I plugged the cable there is no red cross on the NIC card, unlike at work).


Note:

A- With wireless I have got no problem to access the internet at work and at home

B- I do not think that the problem with DHCP server at work,,,,because it is only my laptop has got this problem, if the problem with DHCP server then it should be with all PCs and laptops at work.

Query
Is there any possibility that the administrator mistakenly disabled the wired card (by using MAC address identification) for my laptop from accessing the internet via wired card (not wireless, since it has got different MAC)?

 

[Law]

Yes it is definitely possible that the administrator use MAC address filtering on the swtich to permit and deny certain MAC address on the ports. It makes it hard for anyone to just plug into the network.

Your wireless LAN probably doesn't have any filtering setup and is probably free to use for the employees I suppose. It's probably isolated with a firewall and control so the administrator doesn't really need to worry about setting up every MAC address that connects makeing it less work for the admin.

 

[zillah]

Yes it is definitely possible that the administrator use MAC address filtering on the swtich to permit and deny certain MAC address on the ports.

1- I am aware how to deny or permit certain mac address to access certain port (this is not my case).
But could you please post some documentation show me how to deny a specific mac address to access all ports (not only specific one) belong to the same swtich (this is my case) ?

2- How can I verify that my laptop's mac address has been filtered without asking the administrator , just for my knowledge?

 

[Law]

1- I am aware how to deny or permit certain mac address to access certain port (this is not my case).
But could you please post some documentation show me how to deny a specific mac address to access all ports (not only specific one) belong to the same swtich (this is my case) ?

2- How can I verify that my laptop's mac address has been filtered without asking the administrator , just for my knowledge?

It depends on the switch. Probably all switches can deny a specific address from connecting to it. Other switches like those from Cisco go as far as denying it on the port or all ports. I can't just post any documents without knowing what type of switch your company uses, it's different for everyone.

You really don't know that your laptop is filter until you plug in another computer that is known to be permited and that computer works. You can spoof the MAC address of the computer that is permited to bypass the filter.

 

[zillah]

Thnaks for your contribution

You really don't know that your laptop is filter until you plug in another computer that is known to be permited and that computer works

My answer will be :

Definitely all cables and all wall jack sockets are working because when I tried the same cable and the same wall jack socket on other PCs, they work.

You can spoof the MAC address of the computer that is permited to bypass the filter.

This is what I was thinking, but cann't I just change the MAC address for my laptop to some thing elase (not necessary to be same as one of the permitted PC,,,,i.e. I creat one by my own, but of course I have to be careful not to conflict with another MAC).

Other switches like those from Cisco go as far as denying it on the port or all ports.

Could you please post some documentation related to cisco device.

 

[Law]

You can change it to any MAC address.

Right now I can't even seem to go online, the cisco website doesn't work for me so I can't find any documents. Something is wrong my ISP's DNS server at the moment.

 

[Law]

Finally my Internet is back to normal. Anyways here's a link to Cisco documents on "Managing the MAC address table and Configuring Static MAC address and Port Security"


http://www.cisco.com/univercd/cc/td/doc/product/lan/cat3750/12225sec/3750scg/swadmin.htm#wp1063713

 

[zillah]

Thanks Law for contribution

Finally my Internet is back to normal. Anyways here's a link to Cisco documents on "Managing the MAC address table and Configuring Static MAC address and Port Security"

I think the link below is more relevant to what i was looking for

http://www.cisco.com/en/US/products/hw/switches/ps628/products_configuration_guide_chapter09186a00800d84c8.html

and by looking at the instruction (from the link above) below:

In extended MAC access-list configuration mode, specify to permit or deny any source MAC address or a specific host source MAC address and any destination MAC address.