glm-5.1
dad8224686
Docs: - README.md: index with doc table, ADR table, lifecycle definitions - overview.md: purpose, exports, dependencies, constraints - transport.md: Transport trait, TCP/TLS/iroh implementations, stream join - client.md: SOCKS5 server, port forwarding, channel manager, reconnection - server.md: auth, channel handling, stealth mode, outbound proxy - tun-shim.md: separate privileged process, virtual DNS, --unshare mode - napi-and-pubsub.md: NAPI wrapper, pubsub event target adapter ADRs: - 001: Pluggable transport via AsyncRead+AsyncWrite trait - 002: TUN shim as separate process - 003: iroh stream via tokio::io::join - 004: SSH runs over transport, not alongside - 005: SOCKS5 as primary interface, TUN as add-on - 006(007): NAPI exposes single duplex stream Open questions: 11 items covering TLS certs, iroh relay defaults, Windows TUN, auth expansion, NAPI surface, TCP reconstruction
143 lines
7.2 KiB
Markdown
143 lines
7.2 KiB
Markdown
---
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status: draft
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last_updated: 2026-06-01
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---
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# Client
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## What
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The wraith client establishes an SSH session to a server (via pluggable transport) and exposes local interfaces for routing traffic through that session: SOCKS5 proxy, port forwarding, and eventually TUN.
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## Why
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Users need a way to route traffic through the SSH tunnel. SOCKS5 is the primary interface — it's standard, well-supported by browsers and CLI tools, and needs no privileges. Port forwarding (`-L` / `-R` style) covers specific service access like Postgres or Redis. TUN covers full-system VPN-like behavior.
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## Architecture
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### Client Components
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```
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┌────────────────────────────────────────────────────────┐
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│ wraith connect │
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│ │
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│ ┌──────────┐ ┌──────────┐ ┌──────────┐ ┌──────────┐ │
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│ │ SOCKS5 │ │ Port │ │ Remote │ │ (TUN │ │
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│ │ Server │ │ Forward │ │ Forward │ │ shim) │ │
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│ │ :1080 │ │ -L spec │ │ -R spec │ │ separate │ │
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│ └────┬─────┘ └────┬─────┘ └────┬─────┘ └──────────┘ │
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│ │ │ │ │
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│ ▼ ▼ ▼ │
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│ ┌─────────────────────────────────┐ │
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│ │ Channel Manager │ │
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│ │ (opens direct-tcpip, │ │
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│ │ forwarded-tcpip streams) │ │
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│ └──────────────┬──────────────────┘ │
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│ │ │
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│ ┌──────────────▼──────────────────┐ │
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│ │ SSH Client (russh) │ │
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│ │ Handle<ClientHandler> │ │
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│ └──────────────┬──────────────────┘ │
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│ │ │
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│ ┌──────────────▼──────────────────┐ │
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│ │ Transport │ │
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│ │ (Tcp / Tls / Iroh) │ │
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│ └──────────────────────────────────┘ │
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└────────────────────────────────────────────────────────┘
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```
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### SOCKS5 Server
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The primary client interface. Listens on a local port (default `127.0.0.1:1080`), accepts SOCKS5 connections, and for each connection:
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1. Reads the SOCKS5 handshake (auth method negotiation, target address)
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2. Opens a `channel_open_direct_tcpip(target_host, target_port, originator_addr, originator_port)` on the SSH session
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3. Converts the SSH channel to a stream via `channel.into_stream()`
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4. Runs `tokio::io::copy_bidirectional(&mut local_socket, &mut ssh_stream)` to proxy data
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Supports SOCKS5h (domain names resolved server-side) by default. This prevents DNS leaks.
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### Port Forwarding
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Local port forwards (`-L local_addr:local_port:remote_host:remote_port`):
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1. Bind `TcpListener` on `local_addr:local_port`
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2. For each accepted connection, open `channel_open_direct_tcpip(remote_host, remote_port, ...)`
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3. Proxy bytes bidirectionally via `copy_bidirectional`
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Remote port forwards (`-R remote_addr:remote_port:local_host:local_port`):
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1. Send `tcpip_forward(remote_addr, remote_port)` to request the server listen on a port
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2. When the handler receives `server_channel_open_forwarded_tcpip`, connect to `local_host:local_port`
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3. Proxy bytes bidirectionally
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### Channel Manager
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The channel manager owns the `Arc<client::Handle<ClientHandler>>` and provides methods:
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- `open_direct_tcpip(host, port)` — open a tunnel channel to a remote host
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- `open_streamlocal(socket_path)` — open a tunnel to a Unix socket
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- `request_tcpip_forward(addr, port)` — request remote listening
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- `cancel_tcpip_forward(addr, port)` — cancel remote listening
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It also handles reconnection: if `handle.is_closed()` returns true, attempt reconnection with exponential backoff.
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### Reconnection
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On transport failure:
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1. Detect via `handle.is_closed()` or transport read error
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2. Exponential backoff reconnect (1s, 2s, 4s, ... max 30s)
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3. Re-establish transport connection
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4. Re-authenticate SSH session
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5. Notify SOCKS5 server and port forwards (in-flight connections fail, new connections work)
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Existing TCP connections through the tunnel are lost on reconnect. This is acceptable — same as any VPN.
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### CLI Interface
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```bash
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# Basic connection (TCP, default port 22)
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wraith connect --server example.com --identity ~/.ssh/id_ed25519
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# With TLS
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wraith connect --server example.com:443 --transport tls --identity ~/.ssh/id_ed25519
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# With iroh (no public IP needed)
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wraith connect --peer <endpoint-id> --transport iroh --identity ~/.ssh/id_ed25519
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# SOCKS5 on custom port
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wraith connect --server example.com --socks5 127.0.0.1:1080 --identity ~/.ssh/id_ed25519
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# With port forwards
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wraith connect --server example.com --forward 5432:db.internal:5432 --forward 6379:redis.internal:6379
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# All options
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wraith connect \
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--server <addr> \ # TCP server address (required for tcp/tls)
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--peer <endpoint-id> \ # iroh peer ID (required for iroh)
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--transport tcp|tls|iroh \ # Transport mode
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--identity <path> \ # SSH private key path
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--socks5 <addr:port> \ # SOCKS5 listen address (default: 127.0.0.1:1080)
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--forward <spec> \ # Port forward spec (repeatable)
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--remote-forward <spec> \ # Remote port forward spec (repeatable)
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--proxy <url> # Upstream proxy (SOCKS5/HTTP CONNECT)
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```
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## Constraints
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- SOCKS5 is always enabled when `wraith connect` runs (it's the primary interface). Port forwards are optional.
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- The client does not know or log what destinations are accessed. The SOCKS5 server connects and proxies — no logging of SOCKS5 request targets.
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- Authentication is Ed25519 public key only by default. Password auth supported but not recommended. (OQ-04)
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- Only one SSH session per `wraith connect` process. Multiple sessions = multiple processes (or a future multiplexer).
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## Open Questions
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- **OQ-04**: Authentication beyond Ed25519 keys
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- **OQ-06**: Whether to support SSH config file parsing (`~/.ssh/config`) for default host/key/port settings
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## Design Decisions
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| ADR | Decision | Summary |
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|-----|----------|---------|
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| [005](decisions/005-socks5-before-tun.md) | SOCKS5 first | SOCKS5 is the primary interface, TUN forwards to it | |