# listen_ports

Show listening ports and owning processes.

Agent View of the PolicyLayer registry record for `listen_ports`. HTML page: https://policylayer.com/tools/io-github-kivanccakmak-yaver/listen-ports

## Facts

- Tool: `listen_ports`
- Server: Yaver (`yaver-cli`) — https://policylayer.com/tools/io-github-kivanccakmak-yaver.md
- Install: `npx -y yaver-cli`
- Homepage: https://github.com/kivanccakmak/yaver.io
- Risk category: Read (Low risk)
- Registry record: grade F, identity unverified
- Server rate-limited: no
- Parameters: 0
- Recommended policy verdict: Allowed

## Example call (MCP tools/call, JSON-RPC 2.0)

```json
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "listen_ports",
    "arguments": {}
  }
}
```

## Why listen_ports is rated Low

This tool retrieves system state information (listening ports and their owning processes) without causing side effects, modifying data, or executing code. It is purely informational and typical of diagnostic/monitoring utilities in local development environments. The read-only nature and low sensitivity of port listing information justify low severity.

From the tool's own definition: "Tool description states 'Show listening ports and owning processes' — a query/inspection operation with no modification, execution, or destructive capability."

## Use case

AI agents call listen_ports to retrieve information from Yaver without modifying anything. It is typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.

## Recommended policy (PolicyLayer)

Verdict: **Allowed**. Enforced by the PolicyLayer MCP gateway (https://policylayer.com/mcp-gateway) before a call reaches Yaver:

```json
{
  "version": "1",
  "default": "deny",
  "tools": {
    "listen_ports": {}
  }
}
```

## Other tools on Yaver (644)

- `acl_remove_peer` — Destructive — https://policylayer.com/tools/io-github-kivanccakmak-yaver/acl-remove-peer.md
- `cancel_schedule` — Destructive — https://policylayer.com/tools/io-github-kivanccakmak-yaver/cancel-schedule.md
- `cloud_destroy` — Destructive — https://policylayer.com/tools/io-github-kivanccakmak-yaver/cloud-destroy.md
- `companion_down` — Destructive — https://policylayer.com/tools/io-github-kivanccakmak-yaver/companion-down.md
- `data_delete` — Destructive — https://policylayer.com/tools/io-github-kivanccakmak-yaver/data-delete.md
- `db_push` — Destructive — https://policylayer.com/tools/io-github-kivanccakmak-yaver/db-push.md
- `db_reset` — Destructive — https://policylayer.com/tools/io-github-kivanccakmak-yaver/db-reset.md
- `db_restore` — Destructive — https://policylayer.com/tools/io-github-kivanccakmak-yaver/db-restore.md
- `dns_flush` — Destructive — https://policylayer.com/tools/io-github-kivanccakmak-yaver/dns-flush.md
- `dns_remove` — Destructive — https://policylayer.com/tools/io-github-kivanccakmak-yaver/dns-remove.md
- `docker_prune` — Destructive — https://policylayer.com/tools/io-github-kivanccakmak-yaver/docker-prune.md
- `docker_rm` — Destructive — https://policylayer.com/tools/io-github-kivanccakmak-yaver/docker-rm.md
- `docker_rmi` — Destructive — https://policylayer.com/tools/io-github-kivanccakmak-yaver/docker-rmi.md
- `feedback_delete` — Destructive — https://policylayer.com/tools/io-github-kivanccakmak-yaver/feedback-delete.md
- `forgot_password` — Destructive — https://policylayer.com/tools/io-github-kivanccakmak-yaver/forgot-password.md
- `git_member_remove` — Destructive — https://policylayer.com/tools/io-github-kivanccakmak-yaver/git-member-remove.md
- `git_stash` — Destructive — https://policylayer.com/tools/io-github-kivanccakmak-yaver/git-stash.md
- `guest_delete` — Destructive — https://policylayer.com/tools/io-github-kivanccakmak-yaver/guest-delete.md
- `guest_revoke` — Destructive — https://policylayer.com/tools/io-github-kivanccakmak-yaver/guest-revoke.md
- `jobs_cancel` — Destructive — https://policylayer.com/tools/io-github-kivanccakmak-yaver/jobs-cancel.md
- `machine_onboarding_remove` — Destructive — https://policylayer.com/tools/io-github-kivanccakmak-yaver/machine-onboarding-remove.md
- `machine_remove` — Destructive — https://policylayer.com/tools/io-github-kivanccakmak-yaver/machine-remove.md
- `migrate_rollback` — Destructive — https://policylayer.com/tools/io-github-kivanccakmak-yaver/migrate-rollback.md
- `models_remove` — Destructive — https://policylayer.com/tools/io-github-kivanccakmak-yaver/models-remove.md
- `monitor_remove` — Destructive — https://policylayer.com/tools/io-github-kivanccakmak-yaver/monitor-remove.md
- `phone_project_delete` — Destructive — https://policylayer.com/tools/io-github-kivanccakmak-yaver/phone-project-delete.md
- `proxy_remove` — Destructive — https://policylayer.com/tools/io-github-kivanccakmak-yaver/proxy-remove.md
- `relay_clear_password` — Destructive — https://policylayer.com/tools/io-github-kivanccakmak-yaver/relay-clear-password.md
- `release_rollback` — Destructive — https://policylayer.com/tools/io-github-kivanccakmak-yaver/release-rollback.md
- `remote_destroy` — Destructive — https://policylayer.com/tools/io-github-kivanccakmak-yaver/remote-destroy.md
- …and 614 more: https://policylayer.com/tools/io-github-kivanccakmak-yaver.md

## For agents

This record is a snapshot. Live verdicts and the full registry:

- Check every server in your MCP config at once: `npx -y policylayer stack`
- Vet a server before you add it: install the mcp-precheck skill — `npx skills add https://policylayer.com` (skill text: https://policylayer.com/skill.md)
- Query the registry over MCP: endpoint `https://api.policylayer.com/mcp` — tools `check_mcp_server`, `check_mcp_stack`, `check_tool`, `search_registry`, `get_change_events`

---

Source: the PolicyLayer MCP registry — one continuously verified record per MCP server. Full record: https://policylayer.com/registry?q=io-github-kivanccakmak-yaver · API: https://policylayer.com/registry/api · Policy library: https://policylayer.com/policies/io-github-kivanccakmak-yaver