Re: Patch to make --host_timeout more useful

[Colin Phipps <cph () netcraft com>]

On Tue, Jan 02, 2001 at 10:18:36PM -0800, Fyodor wrote:
> On Mon, 18 Dec 2000, Colin Phipps wrote:
>
> > For people who don't want to wait forever :-), the attached patch makes 
> > nmap print partial results from timed out scans.
>
> Thanks!  That patch will certainly be useful for some users!  However, I
> am not sure about whether it should be in the main distribution.   There
> are a couple important reason that Nmap currently does not try to give
> results for scans that are aborted due to timeout:
>
> 1) User experience -- I am worried that partial results will give people a
> false sense of security.

Very good point. But --host_timeout is not the default; people delving that 
deep into nmap's options ought to have a clue what they are doing.

> 2) Limited benefit -- Even if we give partial results, they generally
> don't know what ports were finished being scanned and so they don't know
> wich ones are left to be tested.

True, it's advisable to disable the random port order with this option.

> 3) Programmer experience -- If I print the results, I need to make sure
> that all the relevant structures are consistant in every single place I
> bail out of a function due to timeout.

True, I didn't look too closely at whether it's safe to exit scans early. 
The patch appears quite stable here, anyway.

> ... So if this really helps some people/applications, speak now or
> forever hold your peace! Also note that for many scans, -v will give you
> partial info as it is discovered.

I tend to view "-v" as a debugging option; it doesn't support the range 
of output formats that the main output does, for instance. If I'm writing 
scripts which take nmap results as input (which I do), which is the better 
option; use -v and look for the "Added TCP port" lines, ignoring the "main" 
output; or use the patched --host_timeout so that I can use the "main" 
results complete with choice of formats? For automated scripts, the timeout 
is essential.

-- 
Colin Phipps                            http://www.netcraft.com/

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