Strange network problem

[lardum]

I have a Cisco PIX running 5.1.4.

I recently bought a brand new laptop (HP Probook 4510s).
With this computer i can access all internal network servers, however Internet can't be reached.

After some troubleshooting i found out that there is something strange with the MAC address of this Probook. If i change the MAC address to some other MAC address everything works fine, but if i change the MAC address to anything in the same scope the problem is still there.

I ran Wireshark on this computer to find out that querys going to the PIX got a checksum error. The exakt error is:
Header checksum: 0x0000 [incorrect, should be 0xb8be]
[Good: False]
[Bad: True]

The MAC address of the new Probook is: 18A905D46685
If i change it to 18A905D46686 i still have the same problem. But if i change it to i.e 001F298CE26C the problem disappears.

The firewall doesn't have any restrictions on who can access the internet. I attach a sample packet from Wireshark if it helps.

Anyone have any ideas on what this could be?

 

[nathanedin]

It is quite possible the PIX does not like the MAC address if it doesn't start with 00: as almost all MACs do. As for a solution... change the MAC to begin with 00.

 

[Viconsul]

Hello,

The 5.1(4) code is very old, you could try a newer Pix code like 6.3(x) and see if that solves the problem.

HTH

-Viconsul