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Anybody here running AD on-prem in your homelab? (lemmy.world)

submitted 9 months ago by [email protected] to c/[email protected]

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I'm curious as to why someone would need to do that short of having a bunch of users and a small office at home. Or maybe managing the family's computers is easier that way?

I was considering a domain controller (biased towards linux since most servers/VMs are linux) but right now, for the homelab, it just seems like a shiny new toy to play with rather than something that can make life easier/more secure. There's also the problem of HA and being locked out of your computer if the DC is down.

Tell me why you're running it and the setup you've got that makes having a DC worth it.

Thanks!

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[–] [email protected] 8 points 9 months ago* (last edited 9 months ago) (1 children)

Yes I do - MS AD DC
I don't have a ton of users, but I have a ton of computers. AD keeps them in sync. Plus I can point services like gitea and vCenter at it for even more. Guacamole highly benefits from this arrangement since I can set the password to match the AD password, and all users on all devices subsequently auto-login, even after a password change.
Used to run single domain controller, now I have two (leftover free forever licenses from college). I plan to upgrade them as a tick/tock so I'm not spending a fortune on licensing frequently
With native Windows clients and I believe sssd realmd joins, the default config is to cache the last hash you used to log in. So if you log in regularly to a server it should have an up to date cache should your DC cluster become unavailable. This feature is also used on corporate laptops that need to roam from the building without an always-on VPN. Enterprises will generally also ensure a backup local account is set up (and optionally auto-rotated) in case the domain becomes unavailable in a bad way so that IT can recover your computer.
I used to run in homemade a Free IPA and a MS AD in a cross forest trust when I started ~5-6y ago on the directory stuff. Windows and Mac were joined to AD, Linux was joined to IPA. (I tried to join Mac to IPA but there was only a limited LDAP connector and AD was more painless and less maintenance). One user to rule them all still. IPA has loads of great features - I especially enjoyed setting my shell, sudoers rules, and ssh keys from the directory to be available everywhere instantly.

But, I had some reliability problems (which may be resolved, I have not followed up) with the update system of IPA at the time, so I ended up burning it down and rejoining all the Linux servers to AD. Since then, the only feature I've lost is centralized sudo and ssh keys (shell can be set in AD if you're clever). sssd handles six key MS group policies using libini, mapping them into relevant PAM policies so you even have some authorization that can be pushed from the DC like in Windows, with some relatively sane defaults.

I will warn - some MS group policies violate Linux INI spec (especially service definitions and firewall rules) can coredump libini, so you should put your Linux servers in a dedicated OU with their own group policies and limited settings in the default domain policy.

[–] [email protected] 2 points 9 months ago* (last edited 9 months ago) (1 children)

Thanks for the great answer.

Using AD for SSO in git-frontends and other applications is a fantastic idea. I will probably also run FreeIPA (that's a name I hadn't heard in a while till this thread, from another commenter) and have a trust relationship.

You're right, this is probably better for learning rather than actually using at home, since most of my computers are linux/BSD, so if I needed a central auth server, I'd probably be better off using something made for *nix.

With that said, I had a curious idea - can I spin up temporary credentials, using something akin to service/machine accounts, rotate credentials and invalidate credentials freely etc? In essence, I'm wondering if this can be a way to implement a sort of homegrown "AWS STS" alternative, for app secrets, workers and the like. I was initially looking at secret management suites like Vault and Conjur but what if this can do it?

Also, can AD encrypt the DB? Can FreeIPA do it? I'd like such an option for security.

Thanks!

[–] [email protected] 2 points 9 months ago (1 children)

I don't have an immediate answer for you on encryption. I know most of the communication is encrypted in flight for AD, and on disk passwords are stored hashed unless the "use reversible encryption field is checked". There are (in Microsoft terms) gMSAs (group-managed service accounts) but other than using one for ADFS (their oath provider), I have little knowledge of how it actually works on the inside.

AD also provides encryption key backup services for Bitlocker (MS full-partition encryption for NTFS) and the local account manager I mentioned, LAPS. Recovering those keys requires either a global admin account or specific permission delegation. On disk, I know MS has an encryption provider that works with the TPM, but I don't have any data about whether that system is used (or where the decryptor is located) for these accounts types with recoverable credentials.

I did read a story recently about a cyber security firm working with an org who had gotten their way all the way down to domain admin, but needed a biometric unlocked Bitwarden to pop the final backup server to "own" the org. They indicated that there was native windows encryption going on, and managed to break in using a now-patched vulnerability in Bitwarden to recover a decryption key achievable by resetting the domain admin's password and doing some windows magic. On my DC at home, all I know is it doesn't need my password to reboot so there's credentials recovery somewhere.

Directly to your question about short term use passwords: I'm not sure there's a way to do it out of the box in MS AD without getting into some overcomplicated process. Accounts themselves can have per-OU password expiration policies that are nanosecond accurate (I know because I once accidentally set a password policy to 365 nanoseconds instead of a year), and you can even set whole account expiry (which would prevent the user from unlocking their expired password with a changed one). Theoretically, you could design/find a system that interacts with your domain to set, impound/encrypt, and manage the account and password expiration of a given set of users, but that would likely be add on software.

[–] [email protected] 2 points 9 months ago

Thanks!