Re: Getting Elapsed time and the Nmap does Not generate the Report

[David Fifield <david () bamsoftware com>]

On Sun, Feb 24, 2013 at 09:50:36PM +0530, Abu Faisal Tauheed wrote:
> I am using the latest Nmap 6.25 for the port scanning.
>
> I have configure ACL on the Node(Network Element) which will block all
> the tcp and udp traffic except some.
>
> Observed behavior : When I have the above configuration in  the NODE
> and  start the UDP scan alone  on Nmap, it does not generate any
> report and it takes forever to complete the execution (actually it
> never complete the execution).

UDP scans can take a very long time because of response rate limiting.
It is important to understand this before beginning. I recommend that
you first try scanning a small number of ports, for example with the
command
        nmap -sU --top-ports 50 --reason -d
That command should take not much longer than a minute to run. If you
see messages like
        Increasing send delay for <target> from 0 to 50 due to max_successful_tryno increase to 4
it means you are encountering rate limiting and the scan will probably
take a very long time. Unfortunately there is no way around it. UDP
responses are commonly rate-limited to one per second--at that rate, it
take over 18 hours to scan 65,535 ports, if that's what you're doing.

> When I was using Nmap 6.01 then I did not face this problem, It only
> started happening from Nmap 6.25.
>
> I am unable to find the 6.01 from your website, If possible can you
> please provide me the Nmap 6.01 so I can test and re-confirm you guys.

Please try http://nmap.org/dist/nmap-6.01-win32.zip or other packages
under http://nmap.org/dist/.

David Fifield
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