Re: max-scan-delay not honored?

[Fyodor <fyodor () insecure org>]

On Fri, Mar 10, 2006 at 07:38:25PM +0100, Filippo Solinas wrote:
> Hi *,
>
> having spent some time playing with the timing & performance
> options in Nmap 4.01, I then realized that --max-scan-delay
> seems not work as expected. Or maybe I'm missing something.
>
> In the following example, max-scan-delay is set to 100 ms,
> but it's never honored, as the delta between probes can put
> in evidence:
>
> -x-
>
> # nmap -P0 -sS -vv --packet-trace -p 0-4,80,81-85 -r --max-parallelism 1 --max-scan-delay 100 --max-retries 0 
> X.Y.Z.100

Here you have told Nmap to send only one probe at a time
(--max-scan-delay 100).  So it needs to wait for each to finish before
it starts the next one.  Otherwise it would be violating your
parallelism restriction (the way Nmap interprets --max-parallelism).
So if you want it to scan faster, you need to decrease the max
round-trip-time (so Nmap doesn't wait as long to finish each probe) or
increase the number of probes allowed in parallel.

Cheers,
-F


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