Re: nmap performance -> timeout issue

[MadHat <madhat () unspecific com>]

On Apr 13, 2005, at 2:22 PM, Maarten Hartsuijker wrote:
> > One point missing...  version of nmap?  I ran into a problem with some
> Latest version (3.81). Tried the RPM as well as a custom compiled 
> version: same issues. I just tried setting max_scan_delay to 0. Nmap 
> now no longer mentions the need for increasing the send delay, but 
> nevertheless, the problems remain.
>
> > I also found that nmap would stall some times on a single host, which 
> > is why I originally wrote my nmap wrapper to run X number of nmap 
> > processes in parallel.  I think at last count I was scanning more 
> > than 180K IPs in less than 16 hours, but I had ICMP enabled for all 
> > my hosts to/from my monitoring host.
> I know nmap will probably be able to do better timing if ICMP is 
> enabled, but I prefer the the audit machine not to have any special 
> privileges when performing scans.

Well, technically ICMP is open to the world on those hosts... so it 
wasn't special.

>  I could run more processes in parallel, by wrapping up some threads 
> from a script, but I think the min_hostgroup option I'm using should 
> achieve more or less the same. Although an improvement of this option 
> might be to have it start new hosts after the first one is finished. 
> Currently I'm scanning 52 hosts simultaniously. 45 hosts that have no 
> open ports perform as they should and finish within the hour. 7 hosts 
> with open ports take about 9,5 hour to complete. It would be nice if 
> it were possible to instruct nmap to start scanning host 53 as soon as 
> the first one is finished, in stead of waiting for all 52 to complete. 
> But this just as a side note. I am really curious why some of the 
> hosts take >9 hours to complete, even though I set all the possible 
> timeout parameters....

My wrapper keeps X number of processes running, so as one finishes, it 
launches another.

My nmap tools are here...
http://www.unspecific.com/.go/nmap/



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