Re: What is your minimum requirement for DHCP and/or a DNS server?
Consumer grade products have minimal OSes on them. A VM will have a more substantial Linux kernel so it's likely going to need at least a little more RAM and CPU than that little router in the plastic box.
Ubuntu Server recommends a minimum of 2 GB disk space to install, for example. I didn't find a RAM requirement, but 512 MB should be plenty. With a VM you can easily change the RAM and disk sizes once you have an idea of how much it will need. If you're just running isc-dhcp-server, and maybe BIND9 for DNS, I expect the space required will be minimal. You'll want ssh as well, so you can log in and tweak things.
Once everything is set up (and you've uninstalled or disabled what you DON'T need), use top, htop and free to see how much RAM you're using. Then size the RAM of the VM accordingly (leave a little buffer).
For disk space, take caching (of DNS), storage of DHCP lease info and logs into account.
If you need DHCP and DNS, you might as well put them in the same VM, unless you have specific security requirements.
Older kernels tend to be smaller than newer ones, so maybe a distro like Centos 7 that uses the 3.10 kernel would fit a tiny VM better than Ubuntu.
I don't know if any VM products can emulate an RPi's architecture or not, but if you can run the rPI OS in a VM it should be able to run in very little RAM. But if you're going to do that, you might as well just run it on a Pi.
Last edited by kpatz; June 13th, 2019 at 02:57 AM.
Current 'buntu systems: multiple systems running Server or Desktop 22.04 LTS / Retired or Upgraded: 18.04.2 LTS, Mythbuntu 16.04 LTS, Ubuntu 16.04.1 LTS, 14.04 LTS, 10.04 LTS, 8.04 LTS
Been using ubuntu since 6.04 (16 years!)
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