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Re: [NSE] find-ssh-hostkey script
From: Toni Ruottu <toni.ruottu () iki fi>
Date: Wed, 9 Mar 2011 19:43:23 +0200

On Wed, Mar 9, 2011 at 5:20 PM, Nick Nikolaou
<nikolasnikolaou1 () gmail com> wrote:
nmap -sC
--script-args newtargets,sshtarget=AB:CD:EF:AB:CD:EF:AB:CD:EF:AB:CD:EF:AB:CD:AB:CD



(The script could be in default category, and just do nothing unless there
is an sshtarget specification in the argument list.)

That's a good idea. I didn't think of that but it's a good example of how
the script can be used.

I forgot. Pre scripts can probably not be in the default category, as
with pre scripts you do not need to specify targets on the command
line, but normally we would want to give an error, if the user does
not specify one.


Is this the type of usage you had in mind


My original idea was to have a way to uniquely identify a host regardless of
IP address. For example it could be useful to a pen-tester working on a
specific machine in a dynamic IP address environment.
I understand that the same thing can be achieved by getting all the
machines' SSH keys, saving them in an output file and using grep to get the
specific machine's IP address, but there may be cases that the script would
simplify this process. (For example scanning using Zenmap?)
Another way of going about this could be adding another parameter to the
existing ssh-hostkey script. Since the script already gets the keys and adds
them to the nmap registry, it could search for the specific key if that
parameter is passed.

How do you decide which computers to check for matching ID?


Nick


On 9 March 2011 14:41, Toni Ruottu <toni.ruottu () iki fi> wrote:

Seems useful, yet I am not sure I fully understand the use case behind
this, and if it would be better to have one script for this, or to
have multiple scripts that can be combined to do the job.

The most obvious use case I can come up for this type of script is one
where I would want to perform a port scan on a host that has a certain
ssh key. I could be the admin of a company that has lots of laptops,
and a dhcp server that assigns IP addresses to those laptops
dynamically. All laptops have an ssh daemon in place for remote
administration. Now the CEO calls me and says there is something wrong
with his laptop. Instead of asking him to figure out the IP address of
his computer, I simply look up a database of ssh keys, and define the
scan target by the ssh key.

nmap -sC --script-args
newtargets,sshtarget=AB:CD:EF:AB:CD:EF:AB:CD:EF:AB:CD:EF:AB:CD:AB:CD

(The script could be in default category, and just do nothing unless
there is an sshtarget specification in the argument list.)

Running the command would use the pre script to locate the machine,
and add it to scan targets. Nmap would then scan the host, and tell me
the ip address of the host and services running on it. Maybe some
script could identify a virus on that machine. If one does not want to
perform full port scan on the host one could set the scan type to ping
scan.

Is this the type of usage you had in mind. This is just the picture I
got. Maybe I misunderstood something.


On Tue, Mar 8, 2011 at 6:45 PM, Nick Nikolaou
<nikolasnikolaou1 () gmail com> wrote:
Hey everyone,

Attached is a script I wrote that attempts to identify a host given its
SSH
hostkey as an argument. I got the idea from Fyodor's presentation

-- () usage
-- nmap --script=find-ssh-hostkey --script-args
fingerprint=AB:CD:EF:AB:CD:EF:AB:CD:EF:AB:CD:EF:AB:CD:AB:CD
--
-- () output
-- 22/tcp  open  ssh
-- |_find-ssh-hostkey: Key found.


After (limited) testing it seems to work. I don't have access to many
machines running SSH so I can't test it thoroughly.

The script name can be confusing seems it's very similar to other
scripts
that show the host's SSH key so feel free to change it to something more
meaningful.

I hope you find it useful.

Any comments are more than welcome.

Nick

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