Mark Rotteveel wrote:

>> Using Wireshark ( <http://www.wireshark.org> www.wireshark.org) i sniffed
>> the network and found some internet protocol errors from the client pcs:
>> Header checksum: 0x0000 [incorrect, should be 0x7854] [Malformed Packet:
>> FB/IB GDS DB]. The same clients pcs can connect to the windows 2003 server
>> 32bit without any error. For testing purpose, I installed the Firebird 2.1
>> 64 bits on the same server and everything works fine with that version,
>> but
>> right now I can't migrate the database to 2.1.
>
> What Wireshark says is not relevant. Header Checksums are usually wrong (Wireshark even indicates a possible reason: TCP offloading). That Malformed Packet warning is either explained by that header checksum or Wireshark supports an earlier Firebird protocol version and the disector stumbles on the differences.

This reminds me of a problem I've seen a few months ago.

Is maybe NOD32 installed on client or server machine. One of my clients
had similar problems, and after investigating, we came to conclusion
that NOD32 is altering TCP packets for some reason.

Once we uninstalled it, everything started to work fine.

--
Milan Babuskov
http://www.flamerobin.org
http://www.guacosoft.com