At 14:01 27/02/01 +0000, Mark Watts wrote:
>[snip]
>
>One thing I'm not sure of (and perhaps someone can enlighten me??) is
>what happens when two internal addresses ping the same machine at the
>same time. Would you end up with two entries for the same external
>address?
Hint: What happens if you are on a host aaa and run 2 instances of ping
to the same remote host.
The payload in the ICMP packet is used to identify the process that needs
to get the response (this is for the 2 pings from a single host). On a NAT
box, this is used to identify the NAT session.
Note that the NAT box may rewrite the payload (this is similar to replacing
the port in TCP/UDP cases) to guarantee unicity (but even without this,
there are very few chances that 2 ICMP "connections" will get the same
payload).
cheers,
mouss
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