Port 3329: HP Device Discovery

What This Port Does

Port 3329 belongs to HP Device Disc (hp-device-disc), Hewlett-Packard's device discovery protocol. It operates on both TCP and UDP and is part of how HP's networked hardware — printers, scanners, multifunction devices — finds and announces itself on enterprise networks.

When an HP device comes online, it needs a way to say "I'm here, I'm a printer, come find me." Port 3329 is one of the channels HP uses for that conversation. It's not a general-purpose protocol. It's a proprietary HP mechanism, registered with IANA by HP engineer Shivaun Albright.¹

The Port Range

Port 3329 falls in the registered port range (1024–49151). These ports are assigned by IANA to specific services — they're not the privileged well-known ports (0–1023) that require root access, but they're not the free-for-all ephemeral ports (49152–65535) either. A registered port means someone asked IANA to reserve this number for their service, and IANA said yes.

In practice, that registration doesn't enforce anything technically. Any process can open any port. Registration is a coordination mechanism, not a lock.

Security Considerations

The SANS Internet Storm Center regularly records scanning activity on port 3329.² This isn't surprising — device discovery protocols are attractive targets because:

• They're often enabled by default on enterprise hardware
• They can reveal what's on a network without authentication
• HP devices are ubiquitous in corporate environments

If you're running HP network hardware and don't need device discovery across network segments, blocking port 3329 at the firewall is reasonable hygiene.

Checking What's Listening

To see if anything is using port 3329 on your system:

macOS / Linux:

# Check for listeners on port 3329
sudo lsof -i :3329

# Or with ss (Linux)
ss -tlnp | grep 3329

# Or with netstat
netstat -an | grep 3329

Windows:

netstat -ano | findstr :3329

If something is listening and you don't recognize it, cross-reference the process ID against your running processes. On a non-HP system with no HP software installed, this port should be silent.