Re: New option: --min-rate for minimum-rate scanning

[Brandon Enright <bmenrigh () ucsd edu>]

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On Sun, 30 Mar 2008 20:44:15 -0600 or thereabouts David Fifield
<david () bamsoftware com> wrote:
...snip...
> That is true, but if the Linux hosts finish faster (for whatever
> reason) and then the Windows hosts have to finish scanning at a
> slower rate, that will bring the overall average down. If you run
> with -d and use the run-time interaction feature by hitting Enter
> during a scan, you can see a live estimate of the current scanning
> rate. You might see it really fast at the beginning and slow down at
> the end.
>
> > I'm happy to try any patch, Nmap command, or network size (up to
> > when Nmap runs out of memory at around /17) so feel free to ask or
> > patch away.
>
> Would you run the tests again with "--max-retries 0"? That will
> eliminate the doAnyOutstandingRetransmits slowdown.
>
> David Fifield

Here we go again, this time with --max-retries 0 like so:

nmap --min-rate 100000 --min-hostgroup 256 --max-retries 0 -P0 -n -d -v -p- <targets>

These are all local machines.  Multiple scans against other machines
were consistent with these so I've only included these three scans:

Linux Box:
Overall sending rates: 89643.44 packets / s, 3944311.23 bytes / s.
Final times for host: srtt: 165 rttvar: 2  to: 100000

Windows Box:
Overall sending rates: 18712.29 packets / s, 823340.93 bytes / s.
Overall sending rates: 18712.29 packets / s, 823340.93 bytes / s.

Nothing:
Overall sending rates: 14538.09 packets / s, 639675.90 bytes / s.
Final times for host: srtt: -1 rttvar: -1  to: 1000000

Local /25:
Overall sending rates: 15573.42 packets / s, 685230.30 bytes / s.

doAnyOutstandingRetransmits was certainly a factor.  It seems something
else though is taking up most of the time.

I can probably profile this and send along the binary/gmon.out if these
results don't make sense.

Brandon

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