Re: [NSE] NTP info gathering script...

[Richard Sammet <richard.sammet () googlemail com>]

Hi David,

thanks a lot for your valuable input.

I tried to follow all of your hints but for the one about testing an
array/table for an element I was not able to implement it like you
noted. It looks like this only works for "hashes" but not for
"arrays":

[quote]
> t = {"test1", "test2", "test3"}
> if t["test2"] then print "foo" end
> t = {test1="test1", test2="test2", test3="test3"}
> if t["test2"] then print "foo" end
foo
>
[/quote]

That's the reason why I still use my function findINtable in the
source. I would be more than happy to get rid of that function as it
is only used once... but I was also not able to find anything useful
with this in the lua manuals and ebooks...

I also added to the script that it fetches the time from the server -
well, this is most obvious when testing a NTP server, isn't it? ;)

For the variables argument - As the variables available really depends
on the implementation of the NTP service (depending on the vendor
there might be some variables we are not aware of yet) I think its a
very useful thing to have the option to print all variables received.

Please find the fixed version attached for an additional review.
Thanks a lot in advance...


Greetings,
Richard


On Sat, Dec 12, 2009 at 9:14 AM, David Fifield <david () bamsoftware com> wrote:
> On Tue, Dec 01, 2009 at 06:29:44PM +0100, Richard Sammet wrote:
> > Well, the next bunch of changes is implemented:
> >  - some more documentation
> >  - Added the function get_timeout() which enables the script to
> > consider the global nmap timing setting (-T*)
> >  - Changed it to make use of stdnse.format_output instead of fiddling
> > around with a string
> >  - Added nmap.set_port_state() - because if the script receives
> > valuable data, the port should be in state=open ;)
>
> Hi Richard, the script looks good and it is straightforward. I want you
> to comment some of the values used in the script:
>
>        string.char(0x16, 0x02, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00)
>        buffer = try(comm.exchange(host, port, request,
>                {lines=16, proto=port.protocol, timeout=timeout}))
>        buffer = string.sub(buffer, 13)
>
> You need to say where the packet payload, and the numbers 16 and 13 come
> from. If possible, provide a link to online documentation of this
> packet.
>
> The test to see if a field should be printed can be done faster and
> clearer without the findINtable function:
>
>        local wlist = {"version", "processor", "system", "refid", "stratum"}
>        for k, v in string.gmatch(buffer, "(%w+)=\"?([^\",]+)\"?") do
>                if wlist[k] then
>                        table.insert(info, string.format("%s: %s", k, v))
>                end
>        end
>
> You could include the test against "any" here but I think script args
> for this script is overkill. Just include the fields that people are
> going to want to see by default. Same with the timeout--just use a good
> default.
>
> > I will freeze it at this stage until public testing is done. And I
> > really hope that I considered all the requirements for nse scripts to
> > be added to the bundle... (are there any detailed nse coding
> > guidelines available?)
>
> The best are
>
> http://nmap.org/book/nse-tutorial.html
> http://nmap.org/book/nsedoc.html
>
> You have a few minor problems in your documentation. You must use
> "@usage" instead of "@sample execution". You don't need to write "@param
> (void)" when a function takes no arguments--just don't use any @param.
>
> David Fifield

Attachment: ntp-info.nse
Description:

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