Update the NAT documentation to make the validation flow easier to
follow.
The existing document already contains useful details, but the test setup
is hard to read for beginners.
- In particular, the NuttX-side commands and Linux host commands can
be confused
- Some commands are redundant
- Some required steps are missing
- The Internet access example is not necessary for NAT behavior itself
Simplify the validation case to use a local topology with Linux network
namespaces. Add an ICMP test case and the required explanations around the
NuttX iptables command and interface roles.
Remove the IPv6 validation case from this doc, since the NAT66 flow
follows the same structure as the NAT44 case.
Signed-off-by: Shunchao Hu <ankohuu@gmail.com>
18cd40cd5d