- Generate random session token on server startup using crypto.randomBytes
- Add authentication middleware requiring Bearer token for all sensitive endpoints
- Apply auth to /mcp, /stdio, /sse, and /message endpoints
- Display session token in console on startup
- Add DANGEROUSLY_OMIT_AUTH environment variable to disable auth for development
- Update README with authentication documentation
This prevents unauthorized access to the proxy server's ability to execute
local processes and connect to MCP servers.
- Change default binding from 0.0.0.0 (all interfaces) to 127.0.0.1 (localhost only)
- Add HOST environment variable to override binding address when needed
- Update console output to show actual binding address
- Document security change in README with warnings about binding to all interfaces
This prevents remote attackers from accessing the MCP Inspector proxy server,
which has the ability to execute local processes. The proxy should only be
accessible from the local machine unless explicitly configured otherwise.
* In server/src/index.ts
- slight format tweak of the Client <-> Proxy message so that the two messages will line up when displayed
* In server/src/mcpProxy.ts
- add reportedServerSession boolean initialized to false
- in transportToServer.onmessage,
- if reportedServerSession isn't set yet, report the sessionId if present on the transport, and then set reportedServerSession to true
* In server/index.js
- in createTransport()
- stringify query params to put them on one line
- remove logging of transport creation (done in callers)
- in /mcp POST handler
- report POST request if session id is present
- otherwise, report new StreamableHttp connection request
- report creation of server transport
- report creation of client transport
- in /stdio GET handler
- report new STDIO connection request
- report creation of server transport
- report creation of client transport
- report 401 as authentication error without stack
- in stderr data handler
- if it includes "MODULE_NOT_FOUND"
- report "Command not found"
- remove transports
- otherwise send to client as usual
- in /sse GET handler
- report SSE connection request
- report 401 as authentication error without stack
- report 404 as server that may not support SSE
- report error with "ECONNREFUSED" as "Connection refused" without stack
- only create, map, and proxy transports if serverTransport was successfully created
- in /message POST handler
- report received POST message
* In mcpProxy.ts
- in onServerError()
- if error message includes 404 OR error.cause includes ECONNREFUSED, report "Connection refused."
Express converts all header names to lowercase, which prevents custom headers with uppercase characters from being properly passed to the target service. This fix ensures that custom headers preserve their original capitalization when forwarded through the proxy.
* In server/src/index.ts
- add delete handler for /mcp endpoint
- gets the server transport for the sessionId
- calls terminateSession on it
- removes the webapp and server transports for the sessionId from the maps
- returns status 200 to the client.
* In client/src/lib/hooks/useConnection.ts
- import Transport
- add useState for clientTransport, type Transport or null initialized to null
- in connect() function
- move creation of client transport down a ways, just before calling client.connect with it
- immendiately efter calling client.connect, call setClientTransport with the connected transport (has to happen after, so that what's saved has the abort controller, etc. otherwise it doesn't work to save it prior.
- in disconnect() function
- immediately call clientTransport.terminateSession if transportType is "streamable-http"
- setClientTransport to null
