Zeek: Not Just Packets — Patterns, Context, and a Ton of Clues
There’s a big difference between seeing packets and understanding what they mean. That’s where Zeek comes in. It doesn’t just capture traffic — it breaks it down, slices it up, and hands you a detailed report of what really happened on the wire.
It’s not flashy. No popups. No dashboards. Just structured logs that make sense — DNS queries, SSL certificates, weird HTTP headers, broken protocols. All there, line by line.
Why Zeek Keeps Showing Up in Real Networks
It speaks protocols, not just ports
It gives you clean logs — readable, searchable, stackable
It doesn’t throw alerts every 5 seconds — it gives you raw material to work with
You can write your own detection logic using its scripting engine
It works great alongside things like Suricata, ELK, or Splunk
It’s open source and regularly updated — without vendor friction
What It Logs (And Why It’s Gold)
| Log | What You Actually See |
| conn.log | Every connection — IPs, ports, duration, protocol |
| dns.log | Who asked for what, and what answer came back |
| http.log | URLs, methods, agents, status codes |
| ssl.log | Certificates, versions, cipher details |
| ssh.log | Fingerprints and handshake info |
| files.log | File transfers on the wire, with metadata and hashes |
| notice.log | Anything your scripts decide is worth flagging |
| weird.log | Protocol oddities — unexpected flags, malformed traffic, etc. |
Where It Belongs
In networks where you can’t afford to miss anomalies
As a quiet backend engine feeding your SIEM or threat tools
In SOCs doing long-term hunts and behavior tracking
On taps or mirrors near sensitive infrastructure
When packet storage is too heavy, but metadata still matters
As a foundation for custom detection logic and event chaining
Getting It Going (Linux, Typically)
Install from packages or grab the install script from zeek.org
Run it on a live interface:
sudo zeek -i eth0
Check the ‘logs/current’ folder — that’s where it writes everything
Want to get fancy? Add your own scripts to trigger alerts or flag patterns
That’s really it. No UI. No background daemons. Just your traffic, analyzed as it flows.
A Few Honest Notes
The learning curve? Yeah, it’s real. But worth it
It won’t scream at you — you have to dig into the logs
Storage can balloon if you don’t rotate or filter
Works best on real interfaces — VPNs and NAT mangle context
ZeekScript is powerful but quirky — prepare to experiment
The Bottom Line
Zeek isn’t magic. It won’t block attacks or quarantine threats. What it gives you is visibility — deep, protocol-level visibility — with enough detail to spot what others miss.
It’s the difference between “we think something happened” and “here’s the DNS request, the SSL cert, the HTTP method, and the exfil — all in one place.”
That’s what makes it so valuable. Not guesses. Not alerts. Just context.
