LuLu Firewall CLI

CLI for managing LuLu macOS firewall rules. LuLu is a free, open-source macOS firewall that blocks unknown outgoing connections.

Requires: macOS 13+, LuLu installed, sudo for write operations.

When to Use This Skill

• A network request fails and you suspect it's being blocked by the firewall
• You need to allow a new domain or service through the firewall
• You want to audit what's currently allowed or blocked
• You need to clean up stale or unnecessary rules
• You're setting up a new machine and need to configure firewall rules

How LuLu Works

LuLu runs as a macOS system extension. When configured in passive mode with new connections defaulting to block, any unrecognized outbound connection is silently blocked and logged as a passive rule.

• Rules live in /Library/Objective-See/LuLu/rules.plist (NSKeyedArchiver binary format, owned by root)
• The CLI reads/writes this file directly using the same serialization format as LuLu
• The system extension only reads rules at startup, so reload (kill + auto-restart) is needed after changes
• New blocks from passive mode appear immediately in recent without needing a reload

Core Workflow

Most usage follows this pattern:

1. Diagnose -- check what's being blocked
2. Fix -- add allow rules for legitimate domains
3. Apply -- reload the extension

# 1. Check recent blocks
lulu-cli recent 10

# 2. Allow the blocked domain
sudo lulu-cli add --key '*' --path '*' --action allow --addr api.example.com --port 443

# 3. Apply
sudo lulu-cli reload

Commands

list [filter]

List all firewall rules. Optionally filter by keyword (matches key or binary path).

lulu-cli list              # all rules
lulu-cli list curl         # rules for curl
lulu-cli list node         # rules for node
lulu-cli list '*'          # global/wildcard rules only

No sudo required.

recent [N]

Show the N most recent block rules, sorted by creation date (newest first). Default: 20.

lulu-cli recent            # last 20 blocks
lulu-cli recent 5          # last 5 blocks

No sudo required. This is the first command to run when diagnosing connection failures.

add

Add a new firewall rule. Requires sudo.

Flags: - --key KEY -- signing identity (e.g. com.apple.curl) or * for global - --path PATH -- binary path or * for global - --action allow|block -- rule action - --addr ADDR -- domain, IP, or regex pattern (default: *) - --port PORT -- port number or * for any (default: *) - --regex -- treat --addr as a regex pattern

# Allow a domain globally (all apps)
sudo lulu-cli add --key '*' --path '*' --action allow --addr example.com --port 443

# Allow a domain and all subdomains (regex)
sudo lulu-cli add --key '*' --path '*' --action allow 
  --addr '^(.+.)?example.com$' --port '*' --regex

# Allow for a specific app only
sudo lulu-cli add --key "/usr/bin/curl" --path /usr/bin/curl 
  --action allow --addr example.com --port 443

# Block a domain
sudo lulu-cli add --key '*' --path '*' --action block --addr malicious.com --port '*'

delete

Delete rule(s) by key. Requires sudo.

Flags: - --key KEY -- required - --uuid UUID -- specific rule UUID. If omitted, deletes ALL rules for the key.

# Delete a specific rule by UUID
sudo lulu-cli delete --key "com.apple.curl" --uuid "A1B2C3D4-..."

# Delete ALL rules for a key
sudo lulu-cli delete --key "com.apple.curl"

delete-match

Delete rules matching specific criteria. Requires sudo.

Flags: - --key KEY -- required - --action allow|block -- optional filter - --addr ADDR -- optional filter - --port PORT -- optional filter

# Delete all block rules on port 53 for curl
sudo lulu-cli delete-match --key "com.apple.curl" --action block --port 53

enable / disable

Toggle a rule's enabled state. Requires sudo.

Flags: - --key KEY -- required - --uuid UUID -- required

sudo lulu-cli enable --key '*' --uuid A1B2C3D4-...
sudo lulu-cli disable --key '*' --uuid A1B2C3D4-...

reload

Restart the LuLu system extension to apply rule changes. Requires sudo.

sudo lulu-cli reload

Kills the extension process. macOS auto-restarts registered system extensions within ~8 seconds. There is a brief gap in filtering during the restart.

Always run reload after add, delete, enable, or disable.

help

Show usage information.

lulu-cli help

Key Concepts

• key: Signing identity (e.g. com.apple.curl) or binary path for unsigned apps. Use * for global rules that apply to all apps.
• action: allow or block
• addr: Domain name, IP address, regex pattern, or * (any)
• port: Port number or * (any)
• type: default (system), apple, user (manually created), passive (auto-created from blocked connections)
• Global rules: key=* and path=* apply to all applications

Rule Policy: Allow-All vs Domain Allowlist

Not all processes should get unrestricted internet access. When using LuLu as a security boundary for AI agents:

Allow-all (addr=* port=*) -- Only for processes the agent cannot invoke: - Apple system daemons (apsd, mDNSResponder, trustd, ocspd, etc.) - User-only apps (Raycast, Zed, LuLu, Bitwarden CLI) - Network infrastructure (Tailscale, ssh)

Domain allowlist only -- Any process an agent could use to reach the internet: - node (Claude Code, OpenClaw runtime) - python / uv (agent scripts) - curl (command-line HTTP) - git / gh (could push to arbitrary remotes) - Browser helpers (agent browser automation)

When in doubt, leave a process restricted to the domain allowlist. It's easy to add an allow-all later; harder to notice data leaking through an over-permissive rule.

Troubleshooting

If a connection is failing:

1. Run lulu-cli recent to see if it was blocked
2. If yes, add an allow rule for the domain + port (usually 443 for HTTPS)
3. Run sudo lulu-cli reload to apply
4. Retry the connection

If the domain doesn't appear in recent, the problem is not the firewall.