Re: Exp Branch for OpenSSL on Windows

[Kris Katterjohn <katterjohn () gmail com>]

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Brandon Enright wrote:
> On Mon, 19 May 2008 20:15:45 -0500 or thereabouts Kris Katterjohn
> <katterjohn () gmail com> wrote:
> ...snip...
> > > I rebuilt nmap with openssl, but it didn't have any appreciable
> > > effect and I note that in the minute that it took to successfully
> > > complete version detection, one of my dual cores was at full-pelt
> > > for around 45 seconds.  I'll look into this more deeply, but I
> > > wonder if anyone else noticed similar?
> > I haven't noticed anything like this happening, but I'll try against
> > some more hosts.  Have you been able to look into it any more?
>
>
> For whatever it's worth, I've been scanning millions of hosts the last
> few days with -sV on SSL ports like 443, 993, 995, etc.  My scans are
> not being limited by my bandwidth but my CPU.
>
> SSL is a very CPU intensive task, especially at the initial RSA parts.
> I don't think there is a bug here, I think people just don't realize
> how expensive quality public-key crypto is.

Yeah, I've since been able to get my CPU >=90% for 30+ seconds with some
hosts.  Most of the hosts I test against may cause a spike for a second
or two, but I now agree that it seems to be normal for some hosts to
throttle the CPU due to SSL.

I didn't know it was quite like that :)

> Brandon

Thanks a lot,
Kris Katterjohn

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