🚀 go-pugleaf

"Paul at NCF" <not plmacca@clara.co.uk> wrote:

>Here's a question for those of you in the know.  Does the TCP/IP checksum 
>field protect against corruption of the data portion, or does it only 
>protect the TCP/IP header?

>Some material on the web implies that the data portion is protected, other 
>sites (including microsoft) imply the header is only included in the 
>checksum (and that the UDP checksum is optional?).

Depends on what layer you are looking at.
http://www.tcpipguide.com/free/t_toc.htm

http://www.tcpipguide.com/free/t_IPDatagramGeneralFormat.htm
IPv4 has a Header CRC, doesn't cover data.

http://www.tcpipguide.com/free/t_IPv6DatagramOverviewandGeneralStructure.htm
IPv6 does away with the Header CRC.

http://www.tcpipguide.com/free/t_IPDatagramEncapsulation.htm
Farther down, closer to the actual transmission, the packet is placed
in a frame. The frame has a footer wich contains a Frame CRC (FCS)
which does cover the data.
http://www.tcpipguide.com/free/t_PPPGeneralFrameFormat.htm

>  And is the answer to this different if you use Win32, Linux, etc?

The protocols are supposed to be agnostic. That's the whole idea.