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Re: nmap performance -> timeout issue
From: "Maarten" <subscriptions () hartsuijker com>
Date: Thu, 14 Apr 2005 13:49:11 +0200 (CEST)

On filtered ports - does the firewall returns ICMP Destination
Unreachables? Are they rate-limited? If yes and yes, try this patch:

Hi martin,

Thanks for making your patches available. I applied, recompiled and
retested, but unfortunately, the delay remains the same.

I did some further testing and it appears that during the scan, it takes
nmap more and more time to process the data. I had it debugging with
(tv_diff > 5) and it seems to climb from less than 5ms in the early
beginning, to more than 100ms at 40%... So I am guessing that this is
where my delay is coming from. Only question left: how can I optimize


SYN Stealth Scan Timing: About 17.46% done; ETC: 12:31 (0:33:06 remaining)
processData took 31ms
SYN Stealth Scan Timing: About 21.62% done; ETC: 12:42 (0:39:53 remaining)
processData took 45ms
SYN Stealth Scan Timing: About 26.42% done; ETC: 12:57 (0:48:45 remaining)
processData took 63ms
SYN Stealth Scan Timing: About 30.57% done; ETC: 13:11 (0:55:40 remaining)
processData took 75ms
SYN Stealth Scan Timing: About 35.37% done; ETC: 13:27 (1:02:11 remaining)
processData took 87ms
SYN Stealth Scan Timing: About 41.05% done; ETC: 13:46 (1:07:33 remaining)
processData took 101ms

6962438 left @ 17%, 33:06, 31ms

5871936 left @ 30%, 55:40, 75ms

4949203 left @ 41%, 1:07:33, 101ms

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