Re: Desired improvements in Nmap performance?

["DePriest, Jason R." <jrdepriest () gmail com>]

On Sun, Nov 30, 2008 at 7:24 PM, David Fifield <> wrote:
> I'm starting a project to improve Nmap's performance and the
> predictability of the length of its scans. This may involve tuning
> performance parameters, adjusting the congestion control mechanism, or
> other things not thought of yet.
>
> What complaints do you have about Nmap's performance? One thing I have
> heard is that for very large scans Nmap may be too slow, or the time
> taken may be too unpredictable.
>
> One possible improvement is I've identified is that sometimes scan delay
> kicks in when I don't think it should. If a scan has just started and I
> see the scan delay go from 0 to 5 ms I'm likely to kill the scan and
> start it over.
>
> Write back with possibilities you see for improvement. I'd like any
> changes we make to be in response to actual user concerns.
>
> David Fifield

The top-ports enhancements have done a great deal to increase the
performance of most of the scans I run.

I would like to see nmap test if it can speed back up after increasing
the delay.  I don't know how often this would need to be done, but
I've seen it, like you mention, add delays when it probably shouldn't.
 If it could check again in five minutes and speed back up, that would
be great.

Perhaps nmap could periodically change its packet rate by monitoring
line conditions.  So if the latency suddenly drops, it can kick it up
automatically.  This would be most useful scanning across a line with
limited bandwidth like a cellular / mobile connection or (ew) dial-up.
 Even web-browsing while scanning can eat up your bandwidth and crowd
nmap out.

-Jason

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