Skip to main content

Experiments with Mikrotik RouterOS NPK Files

I have it in mind to see if I can run a RouterOS virtual router on an Arm device. This is easily done on x86_64 as Mikrotik provide VM images that are ready to go. No so for Arm.

My initial assumptions are that we will need:

  • Root filesystem (SquashFS image in NPK) which does not include a kernel; so
  • A kernel image

Extract the parts of the NPK file​

TODO: Flesh out htis part

https://github.com/botlabsDev/npkpy

Extract a Kernel from "CntZlibDompressedData.raw"​

TODO:

  • Make the script take a file name as a parameter
  • Make the script handle the zlib-flate on it's own

First up, this data blob is compressed with Zlib, decompress it:

sudo apt install qpdf
zlib-flate -uncompress < 010_cnt_CntZlibDompressedData.raw >010_cnt_CntZlibDompressedData

Now use extract_kernel.sh to extract the indervidual files contained within this blob:

bash ./extract_kernel.sh

The result should be a file called kernel in the current directory. The script may have also extracted other files (bash, UPGRADED). I don't think we need these files at this stage.

Booting a VM​

No idea yet. The next steps will need to wait until a future time.

https://qemu-project.gitlab.io/qemu/system/linuxboot.html

  • We probably need to turn 008_cnt_CntSquashFsImage.raw into a partition on virtual disk image
  • sdio for disk interface? IDE? SATA?
  • The end of the kernel file has the kernel command line arguments. Can these be overridden?
    • Added verbosity would be handy
qemu-system-aarch64 -m 2G -smp 2 -M virt,accel=kvm,gic-version=3 -cpu host,pmu=off -kernel ./kernel -drive if=virtio,file=./008_cnt_CntSquashFsImage.raw,id=hd0 -nographic -net none