docs(networking): document SSH-only tag:dntls access to the Macs

docs/docs/reference/networking/tailscale-policy.md

@@ -44,7 +44,7 @@ and trailing commas. Section syntax is documented in Tailscale's
 | `tag:subnet-router` | Devices that advertise lab and home subnet routes into the tailnet | `autogroup:admin` |
 | `tag:sandbox` | Sandbox hosts that accept advertised lab subnet routes | `autogroup:admin` |
 | `tag:agentcompute` | Durable agentcompute HTTPS service | `autogroup:admin` |
-| `tag:dntls` | `dntls` hosts, isolated to each other, Studio, and the MacBook | `autogroup:admin` |
+| `tag:dntls` | `dntls` hosts, isolated to each other plus SSH on Studio and the MacBook | `autogroup:admin` |
 
 A tagged device is owned by its tag, not by the user who registered it. Removing
 a tag from the policy while a device still carries it leaves that device without
@@ -93,23 +93,26 @@ service-to-other-host SSH, and sandbox-to-Studio SSH. OpenSSH separately
 source-pins the service key; see the
 [Studio authorization runbook](../../runbooks/agentcompute-studio-ssh.md).
 
-`tag:dntls` hosts reach each other, Studio, and the MacBook on any port, and
-nothing else in the tailnet:
+`tag:dntls` hosts reach each other on any port and native OpenSSH on Studio and
+the MacBook, and nothing else in the tailnet:
 
 | Source | Destination | Protocol | Port |
 | --- | --- | --- | --- |
 | `tag:dntls` | `tag:dntls` | Any | Any |
-| `tag:dntls` | `studio-1` (`100.122.142.76`), `studio-1-v6` (`fd7a:115c:a1e0::be39:8e4c`) | Any | Any |
-| `tag:dntls` | `macbook-pro` (`100.123.79.63`), `macbook-pro-v6` (`fd7a:115c:a1e0::e701:4f3f`) | Any | Any |
-
-Like `studio-1`, the `macbook-pro` aliases name a user-owned device; do not
-retag the MacBook. The `-v6` aliases admit each device's tailnet IPv6 address;
-MagicDNS names resolve to IPv4 only. Policy tests allow peer, Studio, and
-MacBook ports over both address families and deny an address adjacent to the
-MacBook, the other tags, the Incus cluster API, and routed lab and home hosts.
-Because routed lab addresses are denied, dntls hosts cannot use the split-DNS
-resolver `10.10.10.1` for `glab.lol` and `lab.gilman.io`. Admin-owned devices
-still reach dntls hosts through `autogroup:admin` → `*:*`.
+| `tag:dntls` | `studio-1` (`100.122.142.76`), `studio-1-v6` (`fd7a:115c:a1e0::be39:8e4c`) | TCP | `22` |
+| `tag:dntls` | `macbook-pro` (`100.123.79.63`), `macbook-pro-v6` (`fd7a:115c:a1e0::e701:4f3f`) | TCP | `22` |
+
+There is no Tailscale SSH rule for `tag:dntls`; these are plain OpenSSH
+connections. Tailscale still admits ICMP between any pair of addresses with
+allowed traffic. Like `studio-1`, the `macbook-pro` aliases name a user-owned
+device; do not retag the MacBook. The `-v6` aliases admit each device's tailnet
+IPv6 address; MagicDNS names resolve to IPv4 only. Policy tests allow peer
+ports and SSH on both Macs over both address families, and deny VNC on both
+Macs, an address adjacent to the MacBook, the other tags, the Incus cluster API,
+and routed lab and home hosts. Because routed lab addresses are denied, dntls
+hosts cannot use the split-DNS resolver `10.10.10.1` for `glab.lol` and
+`lab.gilman.io`. Admin-owned devices still reach dntls hosts through
+`autogroup:admin` → `*:*`.
 
 ## Credentials