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RE: [NSE] snmp-ios-config - Config grabber
From: "Thomas Buchanan" <TBuchanan () thecompassgrp net>
Date: Thu, 20 Jan 2011 15:54:01 -0600

-----Original Message-----
From: nmap-dev-bounces () insecure org 
[mailto:nmap-dev-bounces () insecure org] On Behalf Of Patrik Karlsson
Sent: Monday, January 17, 2011 3:26 PM
To: Vikas Singhal
Cc: David Fifield; Thomas Buchanan; nmap-dev
Subject: Re: [NSE] snmp-ios-config - Config grabber

I spent some time during the last few days to write a TFTP 
server implementation for Nmap. It was somewhat harder than I 
had imagined.
The server takes into account that it can be called from 
several scripts simultaneously but uses a single server 
socket to bind to udp port 69.
The script makes use of mutexes and condition variables to 
prevent multiple instances from corrupting global variables 
and to coordinate threads.
Using my test script the library *seems* to work as intended, 
but it needs more testing and preferably a good review of the code.
However, when I incorporated the code into this script, I'm 
getting the following error when nmap is finishing up. Ideas anyone?

NSE: Script Engine Scan Aborted.
An error was thrown by the engine: ./nse_main.lua:279: 
attempt to index field '?' (a nil value)
stack traceback:
      ./nse_main.lua:279: in function 'close'
      ./nse_main.lua:805: in function 'run'
      ./nse_main.lua:1030: in function <./nse_main.lua:937>
      [C]: ?

In addition I've made the following changes to your script.
* changed the socket to be a local variable and made 
sendrequest take it as a parameter
* renamed the tftpserver script argument to 
snmp-ios-config.tftpserver and made it optional
   in case it's not supplied the script attempts to determine 
the local ip itself

Anyway, feedback and suggestions are welcome! I'm attaching a 
patch against your last version and the tftp library.



I spent a little time testing this, and it worked very well in my
environment.  I tested against the same Cisco 1800 series router as
before, and this time tested under both Linux and Windows.  The script
ran successfully and retrieved the config file correctly both times.  I
saw the same error message you did under Linux, but not on my Windows XP
box.  I'm not sure what to make of that.  I don't have multiple Cisco
devices to test, so I can't say anything about how it works with
simultaneous responses.

One question that I have about the script: is there any way to actually
write the configuration to a file, rather than including it in the Nmap
output?  The config file on my Cisco box is roughly 800 lines long, so
this adds quite a bit of noise to the output.  In addition, if I wanted
to run the config through any analyis tools, I'd need to copy and paste,
then remove all the leading '|' characters that NSE output adds.  I
looked through the NSEDoc online, but didn't see anything about writing
to a file, so I don't know if this is feasible, but it would be
convenient in my opinion.

Let me know if you have any questions or need further information.


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