I am looking to set up an SSH entry point into my network via a lightweight Linux or BSD setup.
The purpose of the distro will be to allow SSH access into the rest of the internal network—that's it. It does not need to serve any other function, and for reasons of security, it shouldn't be bloated with loads of unnecessary software.
For further clarity, here is an example of my expected workflow:
user@external-machine:~$ ssh user@ssh-only-distro user@ssh-only-distro's password: user@ssh-only-distro:~$ ssh user@internal-machine user@internal-machine's password: user@internal-machine:~$
Because the distro will be running on a VM with limited resources, I would prefer one which uses only minimal resources. Namely, it should need less than 128 MiB RAM. (The less RAM, the better.)
The distro should also be simple to make persistent on disk. Booting from a live image is fine so long as configurations can easily be saved and pulled on boot without lots of extra tweaking. (This is the chief reason why Micro Core Linux did not work for me.)
Note: A less opinion-oriented version of this question has been posted here: Memory Required for SSH-only Linux Setup