Wireshark · Ethereal-users: [Ethereal-users] Does hardware checksum offload always cause incorrect checksums?

[Anders Thomas Windsor <windsor@xxxxxxxxxxxxxx>]

According to the FAQ checksum offloading can cause incorrect checksums

quote:
Q 5.14: Why am I seeing lots of packets with incorrect TCP checksums?

A: If the packets that have incorrect TCP checksums are all being sent by 
the machine on which Ethereal is running, this is probably because the 
network interface on which you're capturing does TCP checksum offloading. 
That means that the TCP checksum is added to the packet by the network 
interface, not by the OS's TCP/IP stack; when capturing on an interface, 
packets being sent by the host on which you're capturing are directly 
handed to the capture interface by the OS, which means that they are 
handed to the capture interface without a TCP checksum being added to 
them.


Is this always the case? I think my card has checksum offloading, but all 
my checksums are rigt, does that mean the futore is broken on my card 
(according to my drivers checksum offloading is on).

Thanks in advance for any answer.

PS: I'm not on the mailing list, so i can only read replies to this 
e-mail-adress.