Ports, protocols, and CORS

When to use this

You need to change default ports, enable additional transports, or allow browser/MCP clients to call GG from another origin.

Prerequisites

• Installed GG

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Default ports

WebSocket is the default transport for browser edge clients (ws://host:port). TCP is typical for service-to-service backend calls (tcp://host:port).

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Customize ports

Avoid privileged port 80 in development:

./gg ./MyLib.dll --port 8888 --httpPort 8889

Enable TCP for backend callers:

./gg ./MyLib.dll --port 8888 --httpPort 8889 --tcpServer --tcpPort 8990

On the consumer side, set GraftConfig.host accordingly — see Transport selection.

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CORS

For browser-based clients and MCP over HTTP, configure CORS.

CLI

./gg ./MyLib.dll --httpPort 8889 --corsAllowedOrigins "http://localhost:3000,https://app.example.com"

Use * to allow any origin (not recommended with credentials).

Config file (--corsConfig)

allowedOrigins=http://localhost:3000,https://app.example.com
allowedMethods=GET,POST,PUT,PATCH,DELETE,OPTIONS
allowedHeaders=content-type,authorization,MCP-Protocol-Version,Mcp-Session-Id
exposedHeaders=Mcp-Session-Id,MCP-Protocol-Version
allowCredentials=false

./gg ./MyLib.dll --httpPort 8889 --corsConfig ./cors.config

When both --corsAllowedOrigins and --corsConfig are set, the config file is applied at startup and can override CLI defaults.

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Verify it works

# Vision on custom HTTP port
curl -I http://localhost:8889/vision

# MCP port discovery
curl http://localhost:8889/mcpport

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Common mistakes

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See also

• CLI reference
• Transport: TCP, WebSocket, HTTP/2
• MCP: expose tools