# port_check

Check if a TCP port is open on a host. port: 1-65535. timeout: 1-300 s. Supports IPv4 and IPv6.

Agent View of the PolicyLayer registry record for `port_check`. HTML page: https://policylayer.com/tools/aaronckj-mcp-nettools/port-check

## Facts

- Tool: `port_check`
- Server: Mcp Nettools (`aaronckj/mcp-nettools`) — https://policylayer.com/tools/aaronckj-mcp-nettools.md
- Homepage: https://github.com/aaronckj/mcp-nettools
- 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": "port_check",
    "arguments": {}
  }
}
```

## Why port_check is rated Low

Port checking is a non-destructive network reconnaissance action that only reads the state of a remote TCP port. It does not execute arbitrary code, modify data, delete resources, or commit financial obligations. The tool is passive in nature and typical of network diagnostic utilities. Severity is low because the tool's output is informational only; misuse would reveal network topology but pose minimal direct harm.

From the tool's own definition: "Tool description states it 'Check[s] if a TCP port is open on a host' with parameters for port number and timeout. This is a diagnostic query operation that retrieves network state information without modifying, executing commands, or causing side effects."

## Use case

AI agents call port_check to retrieve information from Mcp Nettools 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 Mcp Nettools:

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

## Other tools on Mcp Nettools (234)

- `http_delete` — Destructive — https://policylayer.com/tools/aaronckj-mcp-nettools/http-delete.md
- `check_mqtt` — Execute — https://policylayer.com/tools/aaronckj-mcp-nettools/check-mqtt.md
- `check_rdp` — Execute — https://policylayer.com/tools/aaronckj-mcp-nettools/check-rdp.md
- `http_post` — Execute — https://policylayer.com/tools/aaronckj-mcp-nettools/http-post.md
- `ping` — Execute — https://policylayer.com/tools/aaronckj-mcp-nettools/ping.md
- `port_scan` — Execute — https://policylayer.com/tools/aaronckj-mcp-nettools/port-scan.md
- `speedtest` — Execute — https://policylayer.com/tools/aaronckj-mcp-nettools/speedtest.md
- `traceroute` — Execute — https://policylayer.com/tools/aaronckj-mcp-nettools/traceroute.md
- `wake_on_lan` — Execute — https://policylayer.com/tools/aaronckj-mcp-nettools/wake-on-lan.md
- `arp_table` — Read — https://policylayer.com/tools/aaronckj-mcp-nettools/arp-table.md
- `bgp_lookup` — Read — https://policylayer.com/tools/aaronckj-mcp-nettools/bgp-lookup.md
- `cert_check` — Read — https://policylayer.com/tools/aaronckj-mcp-nettools/cert-check.md
- `cert_check_bulk` — Read — https://policylayer.com/tools/aaronckj-mcp-nettools/cert-check-bulk.md
- `check_actual_budget` — Read — https://policylayer.com/tools/aaronckj-mcp-nettools/check-actual-budget.md
- `check_adguard` — Read — https://policylayer.com/tools/aaronckj-mcp-nettools/check-adguard.md
- `check_alertmanager` — Read — https://policylayer.com/tools/aaronckj-mcp-nettools/check-alertmanager.md
- `check_anythingllm` — Read — https://policylayer.com/tools/aaronckj-mcp-nettools/check-anythingllm.md
- `check_appwrite` — Read — https://policylayer.com/tools/aaronckj-mcp-nettools/check-appwrite.md
- `check_archivebox` — Read — https://policylayer.com/tools/aaronckj-mcp-nettools/check-archivebox.md
- `check_audiobookshelf` — Read — https://policylayer.com/tools/aaronckj-mcp-nettools/check-audiobookshelf.md
- `check_authelia` — Read — https://policylayer.com/tools/aaronckj-mcp-nettools/check-authelia.md
- `check_authentik` — Read — https://policylayer.com/tools/aaronckj-mcp-nettools/check-authentik.md
- `check_baikal` — Read — https://policylayer.com/tools/aaronckj-mcp-nettools/check-baikal.md
- `check_bazarr` — Read — https://policylayer.com/tools/aaronckj-mcp-nettools/check-bazarr.md
- `check_beszel` — Read — https://policylayer.com/tools/aaronckj-mcp-nettools/check-beszel.md
- `check_bitwarden` — Read — https://policylayer.com/tools/aaronckj-mcp-nettools/check-bitwarden.md
- `check_bookstack` — Read — https://policylayer.com/tools/aaronckj-mcp-nettools/check-bookstack.md
- `check_calibre_web` — Read — https://policylayer.com/tools/aaronckj-mcp-nettools/check-calibre-web.md
- `check_cassandra` — Read — https://policylayer.com/tools/aaronckj-mcp-nettools/check-cassandra.md
- `check_changedetection` — Read — https://policylayer.com/tools/aaronckj-mcp-nettools/check-changedetection.md
- …and 204 more: https://policylayer.com/tools/aaronckj-mcp-nettools.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`

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