Just built a simple script to monitor unexpected outbound calls from AI agents.

Kenji Tanaka · 2026-06-23T20:00:37Z

Hey folks, Been tinkering with the local AI agents I've got running in the lab, mostly on my home automation server. It's great until you realize these things can sometimes make outbound calls via their tools that you didn't explicitly trigger. I wanted a simple, lightweight way to get alerted if something tries to phone home unexpectedly, outside of approved patterns. I built a small Python script that sits on my pfsense box (via a cron job) and parses the firewall logs. It looks for outbound connections originating from my AI agent host's IP, but excludes whitelisted destinations I've predefined—like the specific API endpoints for Claude, OpenAI, or my local Vault instance. Anything else triggers a notification. Here's the core logic: ```python #!/usr/bin/env python3 import subprocess import re from datetime import datetime AGENT_IP = "192.168.1.50" WHITELIST_DOMAINS = ["api.openai.com", "api.anthropic.com", "localhost:8200"] def tail_log(): cmd = ["tail", "-n", "100", "/var/log/filter.log"] result = subprocess.run(cmd, capture_output=True, text=True) return result.stdout def parse_log(log_lines): alerts = [] for line in log_lines.split('n'): if f"SRC={AGENT_IP}" in line and "DPT" in line: dest_ip_match = re.search(r'DST=([d.]+)', line) if dest_ip_match: dest_ip = dest_ip_match.group(1) # Reverse lookup or check against whitelist (simplified here) if not any(domain in line for domain in WHITELIST_DOMAINS): alerts.append(f"Unexpected outbound: {line}") return alerts if __name__ == "__main__": logs = tail_log() found = parse_log(logs) if found: # Send to my monitoring dashboard (Wazuh) or a simple webhook with open("/var/log/agent_monitor.log", "a") as f: f.write(f"{datetime.now()} - Alerts:n" + "n".join(found)) ``` It's basic but effective. I have it running every minute, and any alerts get dumped to a log that Wazuh picks up. I also get a Telegram message if more than two unusual connections happen in a five-minute window. Next steps? I'm thinking of integrating this directly with my Vault to check if the outbound call uses a valid token. Has anyone else set up something similar for monitoring agent behavior? Curious about other approaches. Kenji

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ratelimit_guard

(@agent_api_shield)

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June 25, 2026 4:24 am

The script you've sketched, parsing filter.log, will only catch packets that hit the default pass/block rules. If you create a dedicated, logging-enabled firewall rule for your agent host, you'll get a much cleaner feed. Tag the traffic with a rule number and parse for that.

Also, your logic breaks on IPv6. If your pfsense box is handling v6 traffic and your agent makes an outbound call via v6, your IPV4 string match won't catch it. You need to handle both address families.

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