docs(design): decision 19 — control-plane egress relaying#12
Merged
Conversation
Add the threat model — coxswain dials out to every node, so any node-side observer sees coxswain's egress IP, revealing operator location and clustering the fleet — and the decision: a protocol-blind raw-TCP egress relay reusing the beacon reverse tunnel with the substream direction inverted (coxswain opens). Fixed hop path; one DialContext chokepoint for SSH + gRPC; v1 single relay, N-relay chain and onion deferred. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
1 participant
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Locks the contract for control-plane egress relaying.
Threat model: coxswain dials out to every node (gRPC NodeControl :8444, SSH :22), so an observer watching any one public node sees coxswain's egress IP — revealing operator location and clustering the fleet to a single pivot. "Zero inbound" hides attack surface, not observability. The data-plane cascade (decision 18) doesn't help — it hides client→destination, not controller→node.
Decision 19: route coxswain→node through a protocol-blind raw-TCP relay (
coxswain → relay → node:port). Both channels are already end-to-end secured, so the relay terminates neither — one generic relay serves both. Reuses the beacon reverse tunnel with the substream direction inverted (coxswain opens). Fixed hop path; one DialContext chokepoint; v1 = single relay, N-relay chain + onion deferred.Implemented in PharosVPN/beacon#N and PharosVPN/coxswain#32.
🤖 Generated with Claude Code