Port 2600: Unassigned — The Number That Made Hackers

A Registered Port with No Official Tenant

Port 2600 sits in the registered port range (1024–49151). These ports are available for use by applications and services, with assignments tracked by IANA. Unlike well-known ports (0–1023), registered ports don't require elevated privileges to open on most systems.

IANA lists port 2600 as unassigned — no service officially owns it. But unassigned doesn't mean unused.

What Actually Runs Here

Zebra and Quagga Routing Daemons

The most significant unofficial use of port 2600 is zebrasrv, the service port for the GNU Zebra routing software and its widely-used successor, Quagga. These are open-source routing suites that implement BGP, OSPF, RIP, and IS-IS on Linux and Unix systems — the kind of software that lets a commodity server participate in real Internet routing.

Zebra/Quagga allocates a whole neighborhood of ports for its daemons:¹

If you find port 2600 open on a Linux system running network routing software, this is almost certainly why.

HP Storage Manager

IANA's records include a historical listing for hpstgmgr (HP Storage Manager) on port 2600/TCP and UDP, though this service is not widely deployed in modern environments.²

The Number Itself

Port 2600 is unassigned, but the number is anything but anonymous.

2600 Hz is the tone that broke open AT&T's long-distance telephone network. In the late 1950s and early 1960s, phone phreakers discovered that transmitting a 2600 Hz tone down a trunk line signaled to the switch that the call had ended — leaving an open carrier that could be seized to make free long-distance calls. The internal control language of the most powerful communications network in the world reduced to a single pitch.³

In 1971, John "Captain Crunch" Draper learned that a toy whistle packed inside boxes of Cap'n Crunch cereal produced exactly 2600 Hz. He used it. The name stuck.⁴ Later that year, Esquire published "Secrets of the Little Blue Box," introducing phone phreaking to a mass audience — and to two college students named Steve Jobs and Steve Wozniak, who went on to build blue boxes and then Apple Computer.

In 1984, Emmanuel Goldstein (pen name) launched 2600: The Hacker Quarterly, naming it after that tone.⁵ The magazine became the central publication of hacker culture — a place where "how systems really work" was treated as knowledge worth pursuing rather than a threat to contain.

Port 2600 didn't inherit this history by design. But when the Zebra developers picked their port cluster, they picked a number that already meant something to the people who run networks.

Security Considerations

Port 2600 has been associated with Digital RootBeer, a remote-access trojan that used this port for command and control.⁶ If port 2600 is open on a system that isn't running Zebra/Quagga or HP storage software, investigate it.

Unassigned ports are also a common choice for custom services, development tools, and — less charitably — backdoors. An open port 2600 on a consumer device or a server with no routing software installed is worth auditing.

How to Check What's Listening

# Linux/macOS — show process listening on port 2600
sudo ss -tlnp sport = :2600

# macOS alternative
sudo lsof -i :2600

# Windows
netstat -ano | findstr :2600
# Then cross-reference the PID:
tasklist | findstr <PID>