Have you ever been asked for the config of a router or switch you (or someone else) put in so long ago you didn’t remember that device was there? So long ago that the layer of dust inside that switch is probably why the fan stopped spinning and melted it?
Yup, me too. So when it comes time to rebuild it, you go to that customer’s CATTOOLS directory (or configuration manager, or whatever backup tool that they have), and find out that:
- They retired that VM and didn’t tell you
- They let the license lapse
- They forgot about that device when they set up their backups
- They “upgraded” the backup tool, but then never started the service?
- They installed something else that broke the backup service
Yes, “stuff” happens, and backups sometimes don’t, for lots of reasons. This got me to thinking that what I really want (this week) is a PowerShell backup utility for an arbitrary list of network gear at any given client. This beats my previous method of snarfing up cattools directories (when I remember) or backing things up manually whenever I change them (and when I remember) – you see the recurring problem in that method?
Why PowerShell? There’s so many other approaches with Python, Expect, Ansible and so on (all of which can do way more than just backups) – why build something new in PowerShell? Mostly because I can run that on any customer Windows machine and expect it to work, without installing anything the client might have a problem with. Plus I really wanted to play with Carlos Perez’s Posh-SSH code ( https://github.com/darkoperator/Posh-SSH )
So, first, what to back up? What most of my clients run is some subset of:
- Cisco IOS
- Cisco Nexus
- Cisco ASA
- HP Procurve
- HP Comware
- Palo Alto Networks Firewall
Seems like a reasonable starter list? OK, now how to back them up? Again, with the theme of “don’t install anything, don’t change the host you’re running on, and (to quote Ed Skoudis), to ‘live off the land’ ” – this is all in SSH, and all in PowerShell. Essentially for each device: login, do a “show running-config” (or equivalent for that platform), capture the output and save it to ASCII. The credentials never get saved, but you can likely scrape them out of memory if you wanted to make a point.
The input file looks like this (a fictional companyname.in is shown):
The code reads the file as a CSV, so populates a “devices” variable with properties of: devices.name, devices.IP (which can also be a CN or FQDN, it just needs to resolve), and devices.devtype
The 7 device types are covered in the example.in file above. Note that the Palo Alto is in there twice, devicetype 6 for “set” commands – the commands to rebuild the box, devicetype 7 for XML output – which you would use for a full backup, or if you wanted to manipulate that file in another app (stay tuned for that).
Running the Code:
If you run the script with no arguments, you of course get help text:
Running it “for real”, it uses get-credential to collect the userid/password for the devices in the input file. I could save these out, but I’d really rather not leave credentials like this laying around in a file.
The script then motors through the list, device by device. It takes a few minutes, and I could likely make it faster, but I’d rather it be reliable (and done) than a never ending project that never quite works – I really did write this to collect those backups!
Error checking? Umm, not so much, or better stated “not yet”. If you specify a device that doesn’t exist, or if the credentials don’t match, it’ll error out on that device and just go on to the next one in the list. That’d be a good thing for me to get around to fixing (sometime soon maybe)..
The code itself is on my github -> https://github.com/robvandenbrink/rtrbk
Where do I go from here? Give the code a spin,and you tell me! If you’ve got devices you’d like to see added, or other features you’d like to see, please use our comment form to let me know!
Source: SANS Internet Storm Center, InfoCON: green @ February 17, 2017 at 06:45AM