Hacker News Reader

Comment by Arch-TK | Hacker News Reader

People don't want their internal infrastructure to end up in CT logs.

Can confirm. Stood up a test site with SSL on a subdomain recently. Within 2hrs of let's encrypt registration, I was getting hits on file from around the globe with no index defined yet.

DNS-01 + a wildcard SSL cert takes care of that unless you need third level domain names.

I think the last time I issued non-wildcard SSL certs for my domains was when I was still making the mistake of self-hosting email and the entire setup was a rickety mess.

This is a frequently-touted solution, but now somebody compromising printer.lan.example.com can impersonate auth.lan.example.com, which isn't great either.

One approach is to put the wildcard certificate on a proxy. Clients connect to the proxy, and see a valid TLS certificate. The connection from the proxy can use whatever you'd like, including a self-signed certificate that you pin. You have the impersonation problem if the proxy is compromised, but that's a smaller attack surface than "printer", etc.

To be frank that's one of those things where it depends on how much you care about what gets compromised. For a purely internal homelab, the main use is to get software working; the HTTPS is only needed because modern browsers get upset about a compromised secure context if you don't, which leads to them disabling all sorts of random APIs. The actual security component is pretty much secondary for the usecase where you're dealing with devices that exist solely on an intranet - you're already gating off access by different means.

Personally, the way I'd solve the problem in the situation where it'd be a problem is to not put auth on the same domain; auth would go to auth.secondexample.com. That's generally speaking the better choice to begin with due to browser weirdness regarding domain isolation (which is also why you often see software with CDNs use completely different domain names; reddit images being hosted on redd.it for example but also YouTube thumbnails being on ytimg. If they didn't, a maliciously formed file could read out browser storage for different subdomains).

> somebody compromising printer.lan.example.com can impersonate auth.lan.example.com

Nope: one can setup ACLs so that the script that can update the records for printer.lan… cannot also do foo.lan… or any *.lan….

If someone is on your network, you have to start worrying about traffic spoofing, unless you've got a seriously locked down switch (I do). But even so.

Poor security practice to use a wildcard. I completely agree there. But I can understand how wildcard certs work well for the average Joe who just wants internal stuff to be served over TLS without having to think about it too hard.

I work in security, so in my view, having the most secure internal network possible (think ZTA) is certainly up there.

Although I have come up with an alternative approach to achieve this.

> DNS-01 + a wildcard SSL cert takes care of that unless you need third level domain names.

This will allow internal-only services to get LE/ACME certs, but those cert will still show up in the CT logs and be visible to the entire world.

Some folks do not want that visibility, and that's what an internal-only CA gets you.

A wildcard cert is a single cert that is valid for any subdomain. The specific ones you use are not exposed to the CT, just the fact that there is a *.example.com was minted

Let's Encrypt supports wildcard certificates now.

Wildcard certificates are sub-optimal. I have a personal policy of not using them. They become very much like a "shared secret" which you have to properly manage. I know LANs don't need world class security, but as someone who works in security I like to play around with doing things right.

Why CT logs include plaintext domain? Isn't hashing it would be enough?

Make a LE wildcard cert

Reply on news.ycombinator.com