I find it difficult to configure Tailscale for my use case because they seem to completely not support making ACL rules based on the identity of the device rather than a part of the address space. I'm not configuring a router here, I'm configuring a peer-to-peer networking layer... or at least I'm supposed to be...
Last I read the docs while troubleshooting this very problem, you cannot specify node names as the source or destination of a grant. You can specify direct IP address ranges, node groups (including autogenerated ones) or tags, but not names.
Tags permanently erase the user identity from a device, and disable things like Taildrop. When I tried to assign a tag for ACLs, I found that I then could not remove it and had to endure a very laborous process to re-register a Tailscale device that I added to Tailscale for the express purpose of remotely accessing
You can ack based on groups, and you can out users into groups. So if you auth a node, it’s now your node and the ACL for your user / group will apply.
But yes I don’t think you can ACL based o the hostname
Part of the reason that we don't (currently) let you do this is that a hostname is a user-reported field, and can change over time; it's not a durable form of identity that you can write ACLs on. One could imagine, for example:
1. Creating an ACL rule that allows hostname "webserver" to hostname "db".
2. (time passes)
3. Hostname "webserver" is deleted/changed to "web"/etc.
4. Someone can now register a user device with the system hostname set to "webserver"
Should they be allowed to inherit the pre-existing ACL rule?
However, you can accomplish something very close to what you're asking for, I think, by defining a "host" in the policy file (https://tailscale.com/docs/reference/syntax/policy-file#host...) that points to a single Tailscale IP. Since we don't allow non-admins to change their Tailscale IP, this uniquely identifies a single device even if the hostname changes, and thus you can write a policy similar to:
Yes I noticed that when designing our ACL usage. I didn’t find it all that useful unless we were inheriting some non tailscale systems with static IPs that we were going to subnet proxy to w/ tailscale.
Tags are just a better way to do this for tailscale only nodes, as now the ACL doesn’t require any change during a device key rotation.