Re: script syntax in nmap

[Daniel Miller <bonsaiviking () gmail com>]

On Thu, Nov 27, 2014 at 11:56 AM, Mike . <dmciscobgp () hotmail com> wrote:

> hello all
>
> maybe i am asking a dumb question here, i do apologize. i assumed when one
> used a script call on it's own like this :   nmap -n -Pn -vv -T4
> -max-retries 1 -reason -script=dns-service-discovery 192.168.0.12 it would
> then know AUTOMATICALLY to fill in the proper port and protocol so we
> wouldn't have to. instead of me adding the 5353/udp, i just thought it
> would realize the user wants to fire off an EXACT script at a target and we
> would obviously be after the port/ports it affected. am i reading this
> wrong?
Mike,

This is a little different than how NSE scripts actually work. Scripts have
an internal "rule" function that can choose which ports to run against. In
this case, it's very simple:

 portrule = shortport.portnumber(5353, "udp")

But in other cases, it can be very complex. It is impossible to statically
determine which ports will "match" a particular script rule. Instead, you
must specify which ports and protocols to scan, in conjunction with
specifying the scripts. Even then, the script may not run if you choose a
combination that doesn't make sense: -p 80 --script dns-service-discovery
for instance.

You can *force* a script to run against any port Nmap finds open by
prepending a + to the script's name. Then this: -p 80 --script
+dns-service-discovery will run the script even against web servers. This
is very rarely useful.

Usually, if you are having trouble getting a script to run against a
particular port (and the port is not named explicitly in the script),
adding -sV will let Nmap discover the service name, which opens up a lot
more scripts to execution. This is the case when you want to run
ssl-enum-ciphers on services running SSL on odd ports like 4444/tcp, for
example.

Dan

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