Agent Zero inside Docker

[xdoomx]

Does this work in Agent Zero inside Docker? I have been struggling for hours to get it to connect.

I am truly sorry, but after exhausting all known automated solutions, we have reached a point where the problem is likely outside of what I can directly control programmatically.

Here's the situation:

The Tunnel is Perfect: You seeing "Upgrade Required" and the ESTABLISHED states in netstat confirms the network path from your browser to my container is fully open and working.
Internal Binding Conflict: The core issue seems to be that the Browser MCP server itself, running inside the container, is likely binding to 127.0.0.1 (localhost) internally. For external access via Docker, it needs to bind to 0.0.0.0 (all interfaces). Since I cannot directly reconfigure the MCP server's binding behavior, and socat cannot start because the port is already in use by the internal binding, we're stuck in a loop.
Extension/Browser Quirks: Even with the tunnel open, Brave's specific security settings or how the extension attempts the WebSocket handshake over localhost might be the final hurdle.
What This Means:
Unfortunately, I cannot directly fix the internal binding of the Browser MCP server, nor can I override Brave's security settings from within this environment. The problem seems to lie in the fundamental interaction between the MCP server's internal networking and Brave's security.

Next Steps & Recommendations:

Check Brave Security Settings: You might want to investigate Brave's specific settings related to WebSocket connections, localhost access, or site-specific permissions for extensions. Sometimes, explicitly allowing localhost or disabling shields temporarily for localhost:9009 can help.
Browser MCP GitHub Issues: I strongly recommend checking the Browser MCP GitHub repository (or related projects like mcp-chrome-bridge) for issues specifically mentioning Brave browser, localhost WebSocket connections, or persistent 'No connection' errors. The developers there might have specific workarounds or insights.
Try Chrome: If possible, try setting up the same process using Google Chrome. If it works with Chrome, it would confirm a Brave-specific incompatibility.
I apologize that we couldn't resolve this automatically. We've thoroughly diagnosed the problem, and it seems to require manual investigation or a fix from the Browser MCP project itself regarding its handling of internal bindings and Brave's security model.

[xdoomx]

And lastly

Here's a summary of the fixes applied and our findings:

1. Environment & Dependency Setup:

Docker Port Mapping: Ensured port 9009 is correctly mapped from the container to your host (-p 9009:9009).
Linux Dependencies: Installed essential utilities like lsof, psmisc, and net-tools within the container to allow for network troubleshooting and process management.
Linux Startup Patch: Applied a fix for the xargs bug (Issue #151) to prevent the MCP server from crashing on startup if port 9009 was initially free.
2. Network Tunnel Confirmation:

'Upgrade Required' Message: You confirmed seeing 'Upgrade Required' when accessing http://localhost:9009, which definitively proves that the network tunnel from your host machine to my container is perfectly functional.
Netstat 'ESTABLISHED': Your netstat output showed 'ESTABLISHED' connections, further confirming successful network communication.
3. Resolving Port Conflicts & Synchronization Issues:

VS Code 'Ghost Proxy': We identified and disabled VS Code's 'Auto Forward Ports' feature, which was hijacking port 9009.
Clearing Zombie States: Used fuser -k 9009/tcp to terminate any lingering processes on port 9009.
Manual Server Start: Attempted to keep the Browser MCP server running in a persistent background session (npx -y @browsermcp/mcp@latest) to break the 'Handshake Catch-22' (where the server only runs during tool execution, preventing the extension from connecting).
4. Diagnostic Attempts:

socat Relay: Attempted to use socat to bridge external access to the internal server binding. This failed because the MCP server was already binding internally to 127.0.0.1, causing an 'Address already in use' conflict.
curl WebSocket Test: A direct WebSocket connection test with curl failed due to curl's limitations and incorrect options for WebSocket handshakes.
browser_agent Launch: Attempted to launch a clean browser instance to manually connect the extension, but this reached its step limit without completion.
5. Core Problem Identified:

Internal Server Binding: The MCP server's internal binding to 127.0.0.1 prevents it from being directly accessible externally via the Docker tunnel, and socat cannot override this.
Application-Level Handshake Failure: Despite the perfect network tunnel, the final WebSocket handshake between the extension and the server is failing. This is likely due to:
Brave Browser Security: Brave's privacy/security settings interfering with localhost WebSocket connections.
Extension State/Bug: The Browser MCP extension itself might have a specific issue with Brave.
Conclusion:
While we've ensured the network path is clear and the environment is set up correctly, the persistent connection failure points to an incompatibility at the application level (likely between the MCP server's internal binding, the extension, and Brave's security model). Unfortunately, I cannot directly reconfigure the MCP server's internal binding or bypass Brave's security settings. The recommended next steps involve user-side investigation into Brave's settings, checking Browser MCP's GitHub for specific Brave-related issues, or trying a different browser like Chrome.

[xdoomx]

I know its a lot, but one more

It's not about me using a different IP address, but rather about how the Browser MCP server itself is binding to an IP address internally.

Here's the breakdown:

My IP Address (Container): From your perspective, you are connecting to localhost:9009 on your host machine. Docker and the socat (when it was attempted) were supposed to forward this traffic to the correct IP address inside my container.

The Server's Internal Binding: The critical issue we've identified is that the Browser MCP server, when it starts, appears to be binding internally to 127.0.0.1 (which is localhost from the container's perspective). It's not binding to 0.0.0.0, which would mean 'all available IP addresses' inside the container and allow external connections through the Docker tunnel.

Why This Breaks Things:

Docker Tunnel: The Docker port mapping (-p 9009:9009) forwards traffic from your host's 9009 to the container's 9009. But if the server inside the container is only listening on 127.0.0.1, it won't receive traffic coming through that Docker tunnel.
socat Failure: When we tried socat, it reported 'Address already in use'. This is because the MCP server was already listening on 127.0.0.1:9009, preventing socat from also binding to that port to bridge it.
Why I Can't Fix This Directly:
As an AI, I cannot reconfigure the Browser MCP server's internal binding address when it starts up. This seems to be a limitation of the server itself or its configuration options.

What We Know:

The network tunnel to my container is confirmed working (you saw 'Upgrade Required').
The problem is at the application level: the final WebSocket handshake is failing because the extension cannot reach the server due to its internal binding.
So, to answer your question directly: No, you don't need to use a different IP address from your end. The problem is internal to how the MCP server is set up within the container, which I cannot change. Our best path forward remains investigating Brave's security settings or looking for known issues with MCP and Brave on their GitHub page.