# GuruRMM Real-Time Tunnel Implementation Plan

## Overview

Transform GuruRMM agents from periodic check-in mode (30-second heartbeats) to persistent tunnel mode, enabling Claude Code on tech workstation to execute commands on remote machines through secure multiplexed channels.

---

## Architecture Summary

### Current State (Confirmed via exploration)
- **Server:** Axum 0.7 @ 172.16.3.30:3001, WebSocket endpoint, AgentConnections HashMap
- **Agent:** Tokio async, 30-second heartbeat confirmed, 3 concurrent tasks (metrics/network/heartbeat)
- **Protocol:** Tagged JSON enums (ServerMessage/AgentMessage) with serde

### Key Architectural Decisions

1. **Tunnel Lifecycle:** Hybrid - WebSocket stays persistent, tunnel mode is operational state change
   - Agent modes: Heartbeat (default) ↔ Tunnel (active session)
   - One tunnel per agent, on-demand activation, instant mode switching

2. **Channel Multiplexing:** Unified protocol with channel_id routing
   - Single WebSocket, multiple logical channels
   - Enables concurrent operations (multiple terminals, simultaneous file transfers)
   - Channel types: Terminal, FileRead, FileWrite, FileList, Registry, Services

3. **Claude Integration:** Custom MCP server
   - Tools: `gururmm_run_command`, `gururmm_read_file`, `gururmm_write_file`, `gururmm_list_directory`, `gururmm_list_agents`
   - JWT authentication via environment variable
   - Auto-manages tunnel sessions (open on first use, keep-alive, close on idle)

4. **Security:** Three-layer model
   - Layer 1: JWT authentication (24h expiration)
   - Layer 2: Session authorization (tech_sessions table, 4h inactivity timeout)
   - Layer 3: Command validation (working directory allowlist, rate limiting 100/min, audit logging)

---

## Protocol Extensions

### New Message Types

```rust
// Server → Agent
enum ServerMessage {
    // ... existing ...
    TunnelOpen { session_id: String, tech_id: i32 },
    TunnelClose { session_id: String },
    TunnelData { channel_id: String, data: TunnelDataPayload },
}

// Agent → Server
enum AgentMessage {
    // ... existing ...
    TunnelReady { session_id: String },
    TunnelData { channel_id: String, data: TunnelDataPayload },
    TunnelError { channel_id: String, error: String },
}

enum TunnelDataPayload {
    Terminal { command: String },
    TerminalOutput { stdout: String, stderr: String, exit_code: Option<i32> },
    FileRead { path: String },
    FileContent { content: Vec<u8>, mime_type: String },
    FileWrite { path: String, content: Vec<u8> },
    FileList { path: String },
    FileListResult { entries: Vec<FileEntry> },
}
```

### Agent Mode State Machine

```rust
enum AgentMode {
    Heartbeat,  // Default: 30s heartbeats, metrics, network monitoring
    Tunnel {
        session_id: String,
        tech_id: i32,
        channels: HashMap<String, ChannelType>,
    },
}
```

---

## Implementation Phases

### Phase 1: Core Tunnel Infrastructure (Week 1)
**Goal:** Establish tunnel mode switching and channel routing

**Server:**
- Add TunnelOpen/TunnelClose/TunnelData to ServerMessage enum
- Create tech_sessions table (id, session_id, tech_id, agent_id, opened_at, last_activity, status)
- Implement endpoints: POST /api/v1/tunnel/open, POST /close, GET /status/:session_id
- Add channel routing in WebSocket handler (route by channel_id)
- Session validation middleware (JWT + ownership check)

**Agent:**
- Add TunnelReady/TunnelData/TunnelError to AgentMessage enum
- Implement AgentMode state machine
- Add channel manager (HashMap<channel_id, ChannelHandler>)
- Handle TunnelOpen → respond TunnelReady
- Handle TunnelClose → cleanup channels, return to heartbeat mode

**Critical Files:**
- `server/src/ws/mod.rs` - WebSocket handler, protocol definitions
- `server/src/routes/tunnel.rs` - NEW: Tunnel API endpoints
- `server/src/middleware/auth.rs` - Session validation
- `agent/src/transport/websocket.rs` - WebSocket client, protocol handling
- `agent/src/tunnel/mod.rs` - NEW: Tunnel mode manager
- `migrations/XXX_create_tech_sessions.sql` - NEW: Database schema

### Phase 2: Terminal Channel (Week 2)
**Goal:** Execute PowerShell/cmd/bash commands through tunnel

**Implementation:**
- Create TerminalChannel handler on agent (spawn child process, capture streams)
- Implement TunnelDataPayload::Terminal on server
- Working directory validation on agent (configurable allowlist)
- Command result streaming for long-running commands
- Endpoint: POST /api/v1/tunnel/:session_id/command

**Critical Files:**
- `agent/src/tunnel/terminal.rs` - NEW: Terminal channel handler
- `server/src/routes/tunnel.rs` - Add command execution endpoint
- `agent/config.toml` - Add allowed_paths configuration

### Phase 3: File Operations (Week 3)
**Goal:** Read, write, list files through tunnel

**Implementation:**
- Create FileChannel handler on agent
- Chunked transfer for files > 1MB (transfer_id tracking)
- Base64 encoding for binary data
- MIME type detection (magic numbers)
- Endpoints: GET /file, PUT /file, POST /file/list

**Critical Files:**
- `agent/src/tunnel/file.rs` - NEW: File channel handler
- `server/src/routes/tunnel.rs` - Add file operation endpoints
- `common/src/transfer.rs` - NEW: Chunked transfer utilities

### Phase 4: MCP Server Integration (Week 4)
**Goal:** Expose tunnel operations as MCP tools for Claude Code

**Implementation:**
- Create new project: `gururmm-mcp-server` (Rust)
- Use `mcp-server-rs` crate
- Implement 5 core tools (run_command, read_file, write_file, list_dir, list_agents)
- JWT token from environment variable (GURURMM_AUTH_TOKEN)
- Auto-manage tunnel sessions (open on first tool use, 5min idle timeout)

**Critical Files:**
- `mcp-server/src/main.rs` - NEW: MCP server entry point
- `mcp-server/src/tools.rs` - NEW: Tool implementations
- `mcp-server/src/session.rs` - NEW: Session manager
- `mcp-server/Cargo.toml` - NEW: Dependencies

**MCP Config Example:**
```json
{
  "mcpServers": {
    "gururmm": {
      "command": "gururmm-mcp-server",
      "env": {
        "GURURMM_API_URL": "http://172.16.3.30:3001",
        "GURURMM_AUTH_TOKEN": "jwt-token-here"
      }
    }
  }
}
```

### Phase 5: Advanced Features (Week 5+)
- Registry operations (Windows winreg crate)
- Service management (sc.exe/WMI on Windows, systemctl on Linux)
- Interactive terminal with PTY (stretch goal)

---

## Database Schema

```sql
CREATE TABLE tech_sessions (
    id SERIAL PRIMARY KEY,
    session_id VARCHAR(36) UNIQUE NOT NULL,
    tech_id INTEGER NOT NULL REFERENCES techs(id),
    agent_id INTEGER NOT NULL REFERENCES agents(id),
    opened_at TIMESTAMP NOT NULL DEFAULT NOW(),
    last_activity TIMESTAMP NOT NULL DEFAULT NOW(),
    closed_at TIMESTAMP,
    status VARCHAR(20) NOT NULL DEFAULT 'active',
    UNIQUE(tech_id, agent_id, status) WHERE status = 'active'
);

CREATE TABLE tunnel_audit (
    id SERIAL PRIMARY KEY,
    session_id VARCHAR(36) NOT NULL REFERENCES tech_sessions(session_id),
    channel_id VARCHAR(36) NOT NULL,
    operation VARCHAR(50) NOT NULL,
    details JSONB,
    created_at TIMESTAMP NOT NULL DEFAULT NOW()
);

CREATE INDEX idx_tech_sessions_tech ON tech_sessions(tech_id);
CREATE INDEX idx_tech_sessions_agent ON tech_sessions(agent_id);
CREATE INDEX idx_tunnel_audit_session ON tunnel_audit(session_id);
```

---

## API Endpoints (New)

```
POST   /api/v1/tunnel/open
       Body: { "agent_id": 123 }
       Response: { "session_id": "uuid", "status": "active" }

POST   /api/v1/tunnel/close
       Body: { "session_id": "uuid" }

GET    /api/v1/tunnel/status/:session_id

POST   /api/v1/tunnel/:session_id/command
       Body: { "command": "...", "shell": "powershell", "working_dir": "...", "timeout": 30000 }

GET    /api/v1/tunnel/:session_id/file?path=...

PUT    /api/v1/tunnel/:session_id/file?path=...

POST   /api/v1/tunnel/:session_id/file/list?path=...
```

---

## MCP Tools

```
gururmm_run_command(agent_id, command, shell, working_dir, timeout)
gururmm_read_file(agent_id, path)
gururmm_write_file(agent_id, path, content)
gururmm_list_directory(agent_id, path)
gururmm_list_agents()
```

---

## Security Implementation

### Working Directory Validation
```toml
# agent/config.toml
[security]
allowed_paths = ["C:\\Shares", "C:\\Temp"]
```

Agent validates all file operations against allowlist, rejects path traversal (`..`).

### Rate Limiting
- Server enforces: 100 commands per minute per tech per agent
- Sliding window (in-memory or Redis)
- 429 response on limit exceeded
- Violations logged to tunnel_audit

### Command Injection Prevention
- tokio::process::Command (no shell expansion)
- PowerShell: `-NoProfile -NonInteractive -Command`
- Input sanitization (escape quotes, reject backticks)
- Timeout enforcement

### Session Security
- JWT 24h expiration
- Sessions auto-expire 4h inactivity
- One tunnel per agent (prevents concurrent session conflicts)
- Admin force-close endpoint

---

## Testing Strategy

### Unit Tests
- Channel routing (correct channel receives message)
- Session validation (JWT + ownership)
- Command sanitization
- Path validation (traversal prevention)

### Integration Tests
- Full tunnel lifecycle (open → command → close)
- Concurrent sessions to different agents
- Session timeout enforcement
- Rate limiting

### End-to-End Tests
- Claude Code MCP integration
- File upload via MCP, verify on agent
- Multi-step workflow (read file → modify → write back)

---

## Rollout Plan

1. **Week 5:** Internal testing (2 agents: AD2, DESKTOP-0O8A1RL)
2. **Week 6:** Beta release (3 power user techs)
3. **Week 7:** General availability (all techs, documentation, training)

---

## Success Metrics

**Infrastructure (Phase 1-2):**
- 95% tunnel open success rate
- <500ms command response time
- Zero session conflicts

**MCP Integration (Phase 3-4):**
- 80% tech adoption within 2 weeks
- >50 tunnel sessions/day
- <5% command error rate

**Long-term:**
- 20% reduction in RDP sessions
- 90% tech satisfaction
- <1% security incidents

---

## Risks and Mitigations

| Risk | Impact | Mitigation |
|------|--------|------------|
| Command injection | Critical | Input sanitization, no shell expansion, path allowlist |
| Session hijacking | High | Short-lived JWT, session ownership validation, audit logging |
| WebSocket instability | Medium | Auto-reconnect, session recovery |
| Rate limiting too strict | Medium | Configurable per-tech limits, user feedback |

---

## Open Questions

1. Registry operations scope (full access or specific hives only)?
2. Interactive terminal priority (defer to Phase 6)?
3. Multi-tech sessions for pair programming?
4. MCP server credential manager integration (1Password)?
5. Agent-side logging requirements (compliance)?

---

## Verification Plan

### Phase 1 Verification
```bash
# Tech opens tunnel session
curl -X POST http://172.16.3.30:3001/api/v1/tunnel/open \
  -H "Authorization: Bearer $JWT" \
  -d '{"agent_id": 1}'
# Response: {"session_id": "uuid", "status": "active"}

# Check agent logs - should show: "Tunnel mode activated for session uuid"
# Check database: SELECT * FROM tech_sessions WHERE session_id = 'uuid';
```

### Phase 2 Verification
```bash
# Execute command via tunnel
curl -X POST http://172.16.3.30:3001/api/v1/tunnel/$SESSION_ID/command \
  -H "Authorization: Bearer $JWT" \
  -d '{"command": "Get-Date", "shell": "powershell"}'
# Response: {"stdout": "Sunday, April 13, 2026...", "exit_code": 0}
```

### Phase 4 Verification (MCP)
```bash
# Configure MCP server in Claude Code
# Test tools appear in Claude's tool list
# Execute: "List files in C:\Shares on agent ID 1"
# Claude should call gururmm_list_directory tool
# Verify output shows directory listing
```

---

## Next Steps After Approval

1. Create feature branch: `feature/real-time-tunnel`
2. Phase 1 database migrations (tech_sessions, tunnel_audit tables)
3. Update protocol enums (ServerMessage/AgentMessage)
4. Implement tunnel open/close endpoints
5. Update agent WebSocket handler for tunnel mode
6. Unit tests for session validation
7. Deploy to test environment

**Estimated Timeline:** 5 weeks to MCP integration, 7 weeks to GA

---

**Detailed plan location:** `projects/msp-tools/guru-rmm/plans/real-time-tunnel-architecture.md`