Re: [Ethereal-users] Re: Checksum errors

[Ulf Lamping <ulf.lamping@xxxxxx>]

ronnie sahlberg wrote:
> As far as I can tell most implementations with tcp checksum offloading
> specify the checksum as 0 in the apckets captured.
>
>   
Agreed, and  I see checksum offloading on many machines recently ...
> Maybe we should change the tcp checksum code to
> 1, IF checksum checking is enabled and IF the checksum is wrong and IF
> the specified checksum value is 0,   THEN mark it as Checksum:0x0000
> (Checksum Offloaded)
>   
Agreed, but probably better [Checksum Offloaded] :-)
> 2, since tcp checksum errors are VERY rare and would result in either
> a RST or a retransmission anyway making it easy to spot them, we could
> disable checksum checking by default.
>   
Having some checksums checked and others not doesn't seem to be a good 
idea. Disabling all the checksum checks might also be a bad idea.

But having the reassembling code depending on the checksum checks might 
not be a good idea because of that reason. We might try to reassemble 
things even when the checksum fails, when:

a.) the checksum is 0 (I would prefer that)
b.) try it all the time

Regards, ULFL