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Re: [NSE] snmp-ios-config - Config grabber
From: Patrik Karlsson <patrik () cqure net>
Date: Fri, 21 Jan 2011 20:51:27 +0100

On Jan 21, 2011, at 14:05 , Vikas Singhal wrote:

I have access to multiple Cisco devices, I will test the script and will post the output here. 

I did some more testing myself. Unfortunately the TFTP server needs more work.
The current code won't accept two files in parallel, which may result in files not being received due to timeouts.
While this *should* easily be fixed by creating a "server" thread that simply waits for a connection and then starts up 
a new thread that performs the actual transfer it isn't.
For some reason performance suffers horribly once I create code that does this making the server totally unusable.

While I believe in the concept of including a TFTP server, the current code doesn't cut it, so unless I figure out some 
way to re-write this code I think it's a no go.
Any brilliant ideas or solutions are most welcome!


On Fri, Jan 21, 2011 at 4:20 AM, Patrik Karlsson <patrik () cqure net> wrote:

On Jan 20, 2011, at 22:54 , Thomas Buchanan wrote:

-----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.

Ok, thanks for testing!
Vikas, do you have access to multiple Cisco devices against which you can test?

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.

I've added support for saving the contents to separate files specified by the snmp-ios-config.tftproot parameter in 
the attached patch.
I'm not sure how to determine the suitable path delimiter, so for now the path needs to end with a slash.

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



Patrik Karlsson

Patrik Karlsson

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