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Ben Potter
8a4adeec32
Closes https://github.com/coder/coder/issues/15675 Dev servers that bind to the IPv6 wildcard address (Next.js, Node's default `http.Server`, Go's `net.Listen` on wildcard addresses, and others) never showed up in the dashboard Ports panel, even though they were listening and reachable. The agent's port scanner only called `netstat.TCPSocks`, which reads `/proc/net/tcp` (IPv4 only); an `[::]` dual-stack socket lives exclusively in `/proc/net/tcp6`, so the panel reported "No open ports were detected." Also scan `netstat.TCP6Socks` and merge the results into the existing dedupe loop. The IPv6 scan failure is non-fatal so hosts with IPv6 disabled (missing `/proc/net/tcp6`, Windows with the v6 stack off) keep their IPv4 results instead of the Ports panel 500ing. Both captures below: `python3 -m http.server 5123 --bind ::` running in the same workspace, built from main vs this branch ([full recordings](https://github.com/coder/coder/tree/recordings/recordings/ipv6-listening-ports)). ## Before  ## After  <details> <summary>Debugging and decision log</summary> - Reproduced on a dogfood workspace: `next-server` listening on `*:3000` per `ss -tlnp`, `curl` returning 200, but `GET /api/v2/workspaceagents/{agent}/listening-ports` returning `{"ports": []}`. Port 3000 (hex `0BB8`) present in `/proc/net/tcp6`, absent from `/proc/net/tcp`. - Confirmed `agent/ports_supported.go` only calls `netstat.TCPSocks`; the library's `TCP6Socks` (parses `/proc/net/tcp6` on Linux, `GetTcp6Table2` on Windows) was never referenced. - Control test: an IPv4-bound (`0.0.0.0`) listener was detected correctly, isolating the bug to the missing IPv6 scan. - Made the IPv6 scan failure non-fatal after review: returning an error would break the entire ports endpoint (HTTP 500 on every poll) on IPv6-disabled hosts, a regression from the current behavior of "IPv4 ports only." Silent fallback matches the spirit of `ports_unsupported.go`, which returns an empty list rather than erroring. - The fix lives in the OS-backed `osListeningPortsGetter` behind the `ListeningPortsGetter` interface from #20842, so the fake used by coderd tests is unaffected. - Dedupe by port in the existing `seen` map covers dual-stack sockets that appear in both tables on Windows. - `TestOSListeningPortsGetter_IPv6` listens on `[::]:0` and asserts detection; it skips when the host can't bind IPv6. Verified it fails against the pre-fix code. </details> > 🤖 This PR was opened by [Coder Agents](https://coder.com/docs/ai-coder/agents) on behalf of @bpmct.
