Greywall

Greywall is an open source command line tool that lets you watch and control what an AI coding agent does on your machine. You prefix any local agent command with greywall followed by two dashes, and it gives you a live feed of every file read, file write and network connection the agent attempts. It runs on Linux and macOS. The default behavior is to let the agent run while logging everything, so there is no setup pass before you start. From there you can switch to ask mode or deny mode, and apply allow and deny rules through configuration, even in the middle of a session without restarting the agent. A component called GreyProxy records each outbound request, and a dashboard shows pending requests, rules, activity and conversations. It works with agents such as Claude Code and Codex, and is aimed at developers who run agents with permissive settings and want to see, for example, when an agent reads a secrets file or calls a live production API. Greywall is licensed under Apache 2.0, is written in Go, and can be installed with Homebrew, go install or from source. The vendor also offers an install script, which we did not run. The site's current release is listed as version 0.3.1. The project is free and open source, and no paid plan is published. The vendor says it is building a managed governance layer for teams running Greywall across multiple groups, and invites interested teams to get in touch, but no pricing for that is given.