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Checking a larger subnet than I normally do; mapping out a cluster suite in a university for a traffic mapping project (permission attained), and I was wondering something.

NMap usually prints its progress periodically, but I'm unclear to what that 'periodically' is, because the cirrent scan printed a line for basically every 100th of a percent up to 1% done, then one at 1.5%, and has said nothing since.

I suspect that it changes at different 'levels' but does anyone have an actual answer?

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Have you looked at using the following switches -v: Increase verbosity level (use twice or more for greater effect) -d[level]: Set or increase debugging level (Up to 9 is meaningful) – Christopher Wilson Jun 9 '10 at 0:47
Yeah I've used those flags on several other occasions but basically fired this one off on a whim tonight; just wondering what the algorithm is for printing. I'm consulting the source now so hopefully I'll be able to answer later. – Andrew Bolster Jun 9 '10 at 0:58
up vote 3 down vote accepted

After diving through the NMap source (particularly this is what I have for default verbosity and debugging values.

  • If the scan is < 0.003% done, don't print
  • If there is < 1% done, use the following rules, but don't print ETA's
  • If there's < 30 seconds estimated time remaining in the scan, don't print
  • If there's no estimated time, don't print
  • Otherwise, if a previous estimate has been passed (ETA in the past) print a new one
  • Finally, if there's been a change in the ETA of more than 3 minutes, or 5% change in progress, print a new ETA

I think that's basically it but if anyone finds any more rules, feel free to add them in comments and I'll edit them in.

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You can get a status line during a running scan by pressing any key that is not bound to a function (press ? for a list of bindings).

Alternatively, you can pass the --stats-every option with a time value. So this: nmap --stats-every 1m would print a detailed (2-line) status every minute. This status line also shows in the XML output file.

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