🛡️ pfSense MCP Server

Manage your pfSense firewall in plain English — from Claude Desktop, Claude Code, or any MCP client.

332 tools across every subsystem · wire-format verified against the pfSense REST API · safety guardrails on every change

You:     Block all traffic from 203.0.113.5 on WAN
Claude:  ✓ created block rule  →  ✓ applied changes  →  rollback point: config revision 42

You:     Why can't 192.168.1.50 reach the internet?
Claude:  ran diagnostics → gateway WAN_DHCP is down, and a block rule on LAN matches this host

You:     Add a WireGuard peer for my laptop and show me the config
Claude:  ✓ created peer on tun_wg0  →  here's the client config to import

pfSense MCP Server connects Claude Desktop, Claude Code, and any other MCP client to your pfSense firewall. Ask questions, diagnose issues, and change configuration through conversation. Every destructive action needs explicit confirmation, and the server records the config revision it can be rolled back to.

Letting an AI change a production firewall is only safe if the details are right, and that's where the work went:

• A contract-test layer checks every tool's request format against the pfSense REST API schema.

• Every change goes through a multi-layer guardrail pipeline.

• CI runs 661 tests on Python 3.11–3.13, plus an end-to-end MCP protocol test.

Latest release: v1.1.0 · Changelog

Contents

Why this exists · Quick start · What you can do · Safety · Supported versions · Authentication · Deployment · Configuration · Testing · MCP compliance · Known limitations · Architecture · Contributing

Related MCP server: pfSense MCP Server

Why This Exists

Managing a pfSense firewall means clicking through web UI tabs, remembering field names, and hoping you don't fat-finger a rule that locks you out. With this MCP server, you describe what you want in plain English and the AI handles the REST API calls, validates inputs, and warns you before anything destructive happens.

What makes it different:

• Every destructive operation requires explicit confirmation and shows you exactly what will happen

• The config revision is captured before every high-risk change. The response gives the revision ID to restore from Diagnostics › Backup & Restore › Config History in the webGUI, or warns explicitly if no revision could be captured.

• Rate limits on every tool that changes configuration stop a runaway AI loop from flooding your firewall

• Positive input validation (IP/port/MAC/CIDR) plus path-traversal/XSS screening, and secrets redacted from logs and API error responses

• Wire-format verified against the pfSense REST API v2.10.2 schema by a contract-test layer, so tools send exactly what the API expects

Quick Start

Prerequisites:

• Python 3.11 or later.

• pfSense with the REST API v2 package installed. See Supported pfSense versions.

• For Option A, uv.

Option A: run without cloning (uvx):

uvx --from git+https://github.com/gensecaihq/pfsense-mcp-server@v1.1.0 pfsense-mcp-server

Option B: clone for development:

git clone https://github.com/gensecaihq/pfsense-mcp-server.git
cd pfsense-mcp-server
pip install -r requirements.txt
cp .env.example .env
# Edit .env: set PFSENSE_URL, AUTH_METHOD, and credentials

Connect to Claude Desktop. Add the server to claude_desktop_config.json:

• macOS: ~/Library/Application Support/Claude/

• Windows: %APPDATA%\Claude\

Using the installed entry point (Option A):

{
  "mcpServers": {
    "pfsense": {
      "command": "uvx",
      "args": ["--from", "git+https://github.com/gensecaihq/pfsense-mcp-server@v1.1.0", "pfsense-mcp-server"],
      "env": {
        "PFSENSE_URL": "https://192.168.1.1",
        "AUTH_METHOD": "basic",
        "PFSENSE_USERNAME": "admin",
        "PFSENSE_PASSWORD": "your-password",
        "PFSENSE_VERSION": "CE_2_8_1",
        "PFSENSE_CA_FILE": "/path/to/pfsense-ca.pem"
      }
    }
  }
}

Or running from a clone (Option B):

{
  "mcpServers": {
    "pfsense": {
      "command": "python3",
      "args": ["-m", "src.main"],
      "cwd": "/path/to/pfsense-mcp-server",
      "env": {
        "PFSENSE_URL": "https://192.168.1.1",
        "AUTH_METHOD": "basic",
        "PFSENSE_USERNAME": "admin",
        "PFSENSE_PASSWORD": "your-password",
        "PFSENSE_VERSION": "CE_2_8_1",
        "PFSENSE_CA_FILE": "/path/to/pfsense-ca.pem"
      }
    }
  }
}

Remove PFSENSE_CA_FILE if your pfSense certificate is signed by a public CA.

About the CA file. pfSense ships with a self-signed certificate from its own CA, and Python does not read your OS trust store, so verification fails out of the box. Export the CA at System > Cert. Manager > CAs (the export-certificate icon), save the PEM anywhere readable, and point PFSENSE_CA_FILE at it. A missing or unparseable file is a startup error, never a silent downgrade.

VERIFY_SSL=false also connects, and is fine for a throwaway lab. Understand what it costs: nothing authenticates the firewall, so anything that can intercept the connection can read the API key and act as the firewall. This tool changes firewall rules — treat that credential accordingly.

Start talking to your firewall. Open Claude Desktop and ask:

• "Show me all blocked traffic in the last hour"

• "What services are running?"

• "Create a port forward for port 443 to 192.168.1.50"

• "Run a full system health check"

What You Can Do

332 tools across every major pfSense subsystem:

Safety First

AI managing a production firewall needs guardrails. This server has 9 layers:

"Delete firewall rule 5"

  1. CLASSIFY    → HIGH risk (destructive)
  2. ALLOWLIST   → tool is permitted
  3. SANITIZE    → parameters clean (no injection)
  4. RATE LIMIT  → under 10 deletes/minute
  5. DRY RUN?    → user can preview first
  6. CONFIRM     → blocked until confirm=True
  7. BACKUP      → config revision captured
  8. EXECUTE     → API call made
  9. AUDIT LOG   → action recorded with redacted params

Response includes:
  "config_backup": {
    "pre_change_revision_id": 42,
    "rollback_instruction": "To undo this change, restore revision 42 manually in the pfSense webGUI: Diagnostics > Backup & Restore > Config History."
  }

All 201 tools that change configuration carry a guardrail, and a test fails the build if a new one ships without it.

• Every change tool is rate-limited, audit-logged and checked against the allowlist.

• High-risk tools (51): deletes, disconnects, reboot, halt and bulk block are also blocked until the caller passes confirm=True.

• manage_* tools: these require confirm=True for their remove and delete actions.

• Secrets: passwords, keys, PSKs, bind passwords and tokens are redacted in the audit log and in echoed API error responses.

confirm=True is a parameter the MCP client sends. It is not a separate human-approval step, so keep your client's tool-approval prompts on for destructive tools.

You can also:

• Pass dry_run=True to preview any destructive operation without running it.

• Pass verify_descr="Allow HTTPS" to check that you're changing or deleting the rule you expect. This guards against rule IDs shifting.

• Set MCP_READ_ONLY=true to expose only the 131 read-only tools (search, get, diagnose).

• Set MCP_ALLOWED_TOOLS=create_firewall_rule_advanced,delete_firewall_rule to permit only the listed write tools. Read tools stay available.

See SECURITY.md for the vulnerability-disclosure policy and deployment-hardening guidance.

Supported pfSense Versions

Requires the pfSense REST API v2 package by jaredhendrickson13. Package v2.8.x+ ships builds only for CE 2.8.1 and Plus 25.11.1/26.03/26.03.1; CE 2.9.0 and Plus 26.07 need v2.10.1+; v2.7.3 is the last release with builds for CE 2.8.0 and Plus 24.11/25.11.

Security note: run REST API package v2.10.0+. It fixes a command-injection flaw in the interface-group endpoints (GHSA-w3w4-mvcc-vmgr) and adds core command auto-escaping; v2.9.0 fixed an earlier settings-sync privilege escalation (GHSA-8q8g-9f77-8g8g).

v2.10.0 also marks OpenVPNClient.auth_pass, User.ipsecpsk, and WireGuardPeer.presharedkey as sensitive, so the API no longer returns them by default. This server still sets them normally; if a workflow needs to read one back, add a sensitive-field override in the REST API settings.

Authentication

Three methods supported (configure in .env):

Deployment Options

stdio (default) — for Claude Desktop and Claude Code:

python3 -m src.main          # from a clone
pfsense-mcp-server           # via the installed console entry point (pip/uvx/pipx)

HTTP: for remote access and multi-client setups. It requires MCP_API_KEY, and the server refuses to start with an empty, placeholder or short token.

export MCP_API_KEY="$(python3 -c 'import secrets; print(secrets.token_urlsafe(32))')"
python3 -m src.main -t streamable-http --port 3000

The HTTP transport is plain HTTP. Put it behind a TLS-terminating reverse proxy before exposing it beyond localhost.

Docker: a hardened container running the HTTP transport.

cp .env.example .env        # set PFSENSE_URL, credentials, and MCP_API_KEY
docker compose up -d

The published port binds to 127.0.0.1 by default. Set MCP_BIND_ADDR=0.0.0.0 to expose it, but only behind TLS. For a private CA, put the PEM in ./certs/ and set PFSENSE_CA_FILE=/certs/<file>.pem.

Container security:

• Runs as a non-root user (mcp:1000).

• Read-only filesystem, a noexec tmpfs, and no-new-privileges.

• All Linux capabilities dropped.

The health check probes an unauthenticated /health endpoint, because /mcp requires the bearer token.

Behind an MCP gateway — the HTTP transport is a spec-compliant Streamable HTTP endpoint with bearer-token auth, so it can be registered as an MCP-server target behind managed gateways such as AWS Bedrock AgentCore Gateway (use its API-key credential provider to supply the MCP_API_KEY bearer token, and add the gateway's origin to MCP_ALLOWED_ORIGINS). Such gateways add centralized OAuth/IAM in front and translate between protocol revisions, including 2026-07-28. No gateway is required — this is purely an option for environments that already run one.

Configuration

Boolean settings accept true/false, 1/0, yes/no or on/off. Any other value stops the server at startup rather than guessing, so a typo can't turn off TLS verification.

Response Encoding (GCF)

By default the tools return JSON. Setting RESPONSE_FORMAT=gcf returns each eligible tool result as a single Graph Compact Format block instead: the record arrays these read tools produce (firewall rules, aliases, DHCP leases, certificates, DNS records) have their repeated field names factored into one header, cutting the token cost when the result crosses the LLM boundary. Results that are not a single JSON body — or that GCF would not shrink — stay JSON (see below).

Install the optional extra into the server's environment and set the variable:

pip install '.[gcf]'        # from a clone of this repo
export RESPONSE_FORMAT=gcf

# or, with uvx (the extra must go into uvx's isolated tool environment):
RESPONSE_FORMAT=gcf uvx --with 'gcf-python[fastmcp]==2.7.1' \
  --from git+https://github.com/gensecaihq/pfsense-mcp-server pfsense-mcp-server

It is opt-in and conservative — GCF is used only when it is both smaller than the JSON and a verified lossless round-trip, otherwise the JSON is kept, so no record is ever dropped or altered. structuredContent is preserved, so output-schema validation and non-model clients keep receiving JSON. If the gcf extra is not installed, the server logs a warning and continues with JSON.

Token savings on representative 30-record results (o200k tokens, lossless; reproduce with python benchmarks/gcf_benchmark.py):

Testing

python3 -m pytest tests/ -v          # 661 tests
python3 -m pytest tests/ --cov=src   # with coverage (~50%)

The suite includes a wire-contract layer (tests/contract/) that asserts every tool's payload against the real pfSense REST API v2.10.2 schema (distilled from the upstream OpenAPI spec), so a wrong field name or type is a failing test rather than a silent misconfiguration. CI runs on Python 3.11/3.12/3.13 with pip-audit dependency scanning.

In addition to the in-process suite, an end-to-end protocol smoke test drives the server over the real MCP wire protocol using the official MCP Inspector CLI. It covers both transports and runs in CI on every push:

make test-e2e            # or: ./scripts/inspector_smoke.sh  (needs node/npx, jq)

It verifies the initialize handshake, the 332-tool listing with annotations, the guardrail confirm-gate over the wire, read-only mode, and HTTP bearer-auth plus Origin enforcement — no pfSense instance required.

MCP Specification Compliance

Compliant with MCP 2025-11-25 — the newest revision with stable SDK support — and negotiates down to older revisions per connection, so existing clients keep working:

• ToolAnnotations on all 332 tools (readOnlyHint, destructiveHint, idempotentHint)

• serverInfo.version and instructions provided

• Origin header validation (MUST requirement)

• Bearer token auth with timing-safe comparison

• Default bind to localhost per spec SHOULD

• stdio and Streamable HTTP transports

The stateless 2026-07-28 revision

MCP 2026-07-28 removes the initialize handshake and protocol-level sessions, so every request stands on its own. SDK support ships in fastmcp 4, which is now stable (4.0.5).

Status: this release pins fastmcp 3.x (MCP 2025-11-25). A non-blocking CI job runs the full test suite and the MCP Inspector smoke test against fastmcp 4.0.x, and both pass unchanged. The server holds no session state by design, and it uses none of the features that 2026-07-28 deprecates (Roots, Sampling, MCP Logging).

The pin will move to fastmcp 4 once the smoke test also covers sessionless requests, which skip initialize. fastmcp 4 negotiates the protocol version per connection, so clients that use the handshake will keep working.

Project Structure

src/
  main.py              Entry point (transports, read-only filter, key validation)
  server.py            FastMCP instance + API client
  client.py            pfSense REST API v2 HTTP client (retry/backoff, pooling)
  guardrails.py        Risk classification, confirm gate, rate limit, audit, redaction
  helpers.py           Validation, parsing, pagination, safety guards
  models.py            Data models
  middleware.py        HTTP bearer auth + Origin validation + /health
  tools/               34 tool modules (332 tools)
scripts/
  generate_contract.py Regenerate the wire contract from an OpenAPI spec
  generate_token.py    Generate a secure MCP_API_KEY bearer token
  inspector_smoke.sh   End-to-end MCP protocol smoke test (MCP Inspector CLI)
tests/                 661 tests (incl. tests/contract/ wire-contract suite)

See ARCHITECTURE.md for the request lifecycle, guardrail model, and wire-contract layer; SECURITY.md for disclosure and hardening; and RELEASE_AUDIT.md for the audit and roadmap.

Known Limitations

These are tracked for the next release:

• About 11 update/delete tools for nested objects don't send the parent_id the REST API requires, so those calls fail (#79). Affected objects are DHCP address pools and custom options, traffic-shaper queues, IPsec encryption entries and schedule time ranges.

• create_ipsec_phase1 and create_ipsec_phase2 don't yet send the nested encryption settings the API requires. Fixing them needs validation against a live pfSense.

• The REST API has no config-restore endpoint, so rolling back a change is a manual step in the webGUI. Use the revision ID that guarded tools return.

• Each server process manages a single pfSense instance.

Contributing

We need real-world testing across diverse pfSense environments. See CONTRIBUTING or:

1. Fork and create a feature branch

2. Run python3 -m pytest tests/ -v

3. Submit a PR

Ideas: integration tests against real pfSense, additional package support (Snort, Suricata), Ollama local LLM bridge, multi-instance management.

License

MIT

Acknowledgments

• jaredhendrickson13 / pfrest — pfSense REST API v2 package

• JeremiahChurch — modular rewrite (PR #5), log endpoint OOM safeguards (PR #6), DHCP static-mapping search fix (PR #91)

• shawnpetersen — API v2 endpoint discovery (PR #3)

• aemitic — DELETE-body fix (PR #9), firewall ipprotocol for IPv6/dual-stack (PR #10), logconfigchanges (PR #11)

• pbhorjee — live-status diagnostics fix (PR #21), firewall-log freshness + exact-IP filtering (PR #23), redirect credential guard (PR #72), 503 write-retry fix (PR #74), transport-error context (PR #75), alias edit locking (PR #76), retry jitter and budget (PR #77), private-CA report (#73)

• DrewKolstad — interface addressing, null-safe search filters, WireGuard allowed IPs, DHCP lease times (PR #78)

• msarg44 — get_pf_table / get_config_revision fix (PR #80)

• cbrown350 — get_log_file raw log reads (PR #90)

• blackwell-systems — optional GCF response encoding (PR #87)

• bholland-bh — pfSense CE 2.9.0 / Plus 26.07 support request (#88)

• hossamnagy — resilient startup on transient preflight failure (PR #14)

• bill-mccormick-dg — independent DELETE-body fix (PR #16)

• w1ld3r — DELETE and remote-syslog bug reports (#12, #13)

• tvlc — WebGUI port type-mismatch report (#7)

• renanwilliam — uvx/pipx packaging request (#8)

• Netgate — pfSense

• FastMCP — MCP framework