SSH Banner Error Fix Implementation

Problem

The multi-agent supervisor system was creating multiple SSH connections simultaneously, causing "Error reading SSH protocol banner" errors. This happened because each agent that needed SSH access was creating its own connection to the remote server.

Root Cause

Multiple agents attempting to establish SSH connections in parallel
SSH server or network infrastructure rejecting rapid connection attempts
No connection pooling or sharing mechanism

Solution Implemented

1. SSH Connection Manager (`ssh_connection_manager.py`)

Singleton pattern to manage shared SSH connections
Thread-safe connection pooling to prevent multiple connections to the same host
Global execution lock to serialize SSH operations across all agents
Automatic connection cleanup on exit

Key features:

One connection per unique host/user/port combination
200ms delay between operations to prevent rapid connections
Proper cleanup of connections on exit

2. Updated SSH Tool (`ssh_tool.py`)

Added use_shared_connection parameter (defaults to True)
Integration with the connection manager
Thread-safe execution through the connection manager's lock
Backward compatibility for non-shared connections

3. Updated Configuration (`init.py`)

Pre-configured SSH tool now uses shared connections
Import and export of the SSH connection manager
Clear documentation of the shared connection feature

4. Enhanced Supervisor (`main-multi-agent.py`)

Updated prompt to emphasize sequential execution over parallel
Added proper SSH connection cleanup on exit
Improved error handling and resource management

5. Sequential Executor (`sequential_executor.py`)

Additional layer of protection against parallel execution
300ms delay between agent executions
Comprehensive logging for debugging

Key Benefits

Eliminates SSH Banner Errors: Only one connection per server
Improved Reliability: Prevents connection flooding
Better Resource Management: Shared connections reduce overhead
Thread Safety: Proper locking prevents race conditions
Graceful Cleanup: Connections are properly closed on exit

Configuration

The system is now configured to:

Use shared SSH connections by default
Execute agent operations sequentially when SSH is involved
Automatically clean up connections on exit
Provide clear error messages if issues occur

Testing

A test script (test_ssh_sharing.py) has been created to verify:

Connection sharing is working correctly
Sequential execution is enforced
Cleanup works properly

Usage

The system now works exactly as before from the user's perspective, but with improved reliability:

cd /Users/ghsioux/tmp/langgraph-pard0x/multi-agent-supervisor
python main-multi-agent.py

Users can query the system normally, and the SSH operations will be handled reliably in the background.

Technical Details

Connection Key: username@host:port uniquely identifies connections
Execution Lock: Global thread lock ensures sequential SSH operations
Delay Strategy: Small delays prevent rapid connection attempts
Cleanup Strategy: Automatic cleanup on normal exit and SIGINT

This implementation resolves the SSH banner errors while maintaining the full functionality of the multi-agent system.

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