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"Inveniam viam aut faciam" : I will either find a way, or I shall make one


While cisco is a vendor specific product, the brand-name has become synonymous with networking. So for better or worse, you will at some stage probably need to audit a cisco configuration file. Now there are some easy ways to do this, but I just want to explain some cavaets:
  1. What follows will never be as good as a knowledgeable 'human' review
  2. What follows will not be of much use for the extreme high-end cisco enterprise products
  3. Because what follows describes an automated process, always review findings
Ok, with such dire warnings why would you want to go any further? Because while gaining competence with cisco is never a bad thing, sometimes you just do not have the time and/or you need some quick answers - kinda like running nmap rather then manually using telnet .... just kidding.

Now to start with you need a cisco config, you can get this by dumping the output of the "show run" command. This dump file will be a list of all the settings that make your cisco device function just the way you hope it should. Now for the tool. The tool that is famous for this type of work is a tool called "nipper". Now this tool was open-source, but a while ago it went commercial. You can purchase the commercial tool obviously, but I am cheap and you can still find the previous open-source versions (see here, here and here). Once you extract the zip file you will have the nipper.exe binary. Running "nipper --help", will give you a bunch of the different options but lets just keep it simple for now. Lets run it against our configuration dump file..

Simple. Now if you take a look at your you will see a whole bunch of data, all very useful to pore over, but for now just take a look at the sections (the 2.x sections) which show any identified risk areas. You should see something like..

Nice! Now please, you should go through these findings just as a sanity check - automated tools are never 100%.

But what if you have lots of config files to go through at one time? Is that easy? Why yes, yes it is.
  1. Put all your config dump files into the same folder as the nipper binary (because I am lazy)
  2. Run this dos command in that folder: for %X in (*.txt) do (nipper --text –-input=%X –-output=%X-rpt.txt)
  3. That will create a report file for each config file. 
  4. Now download the UnxUtils (here), these are linux binaries ported over to windows binaries (again because I am lazy)
  5. From that zip, extract the grep.exe, cut.exe, sort.exe, uniq.exe binaries to the nipper folder
  6. Run this dos command: grep -H ", 2\." ./*.txt-rpt.txt  | cut -f 1-3 -d "," > list.txt
  7. This will pull all  different security issues into one file as well as which configuration file it is from
  8. Now run this dos command: type list.txt | cut -f 2 -d ":" | sort | uniq > ./threat.txt
  9. This creates a simple list of all threats
  10.  Now run this:for /f "delims=: tokens=1" %X in (threat.txt) do (echo %X >> rpt.txt) && (@grep "%X" list.txt | cut -f 1 -d ":" >> rpt.txt ) && (@echo ================= >> rpt.txt) 
  11. This will create a report file (rpt.txt) that list each security issue found followed by a list of configuration files relevant to that issue
  12. Now copy/paste/massage the data as needed
Final Words
Nipper can do a lot more, but for a quick check through, it can make your life a lot easier .... just a pity about the whole "going commercial" thing. Anyway, have fun, play and learn.