Port 3167: Now Contact Public Server — A Registered Port with a Ghost Tenant

What Port 3167 Is

Port 3167 sits in the registered ports range (1024–49151), the middle tier of the port numbering system. These ports are assigned by IANA through a formal registration process and are intended for specific applications rather than core Internet infrastructure.

IANA's official record assigns port 3167 to "Now Contact Public Server" — a server component for Now Contact, a contact management application published by Now Software in the late 1990s. Now Software was acquired and the product line discontinued. The port registration remains. The software does not.¹

This is not unusual. Thousands of registered ports carry assignments from applications that were abandoned, acquired, or simply forgotten. The registry is a historical record as much as it is a functional directory.

Does Anything Use This Port Today?

In practice, no standard service listens on port 3167. A few databases note that UDP ports in the range 3074–3174 are used by Tom Clancy's Rainbow Six Vegas for multiplayer matchmaking, which would technically include 3167, though this is a broad range claim rather than a specific assignment.²

No known malware or exploit toolkits specifically target or use this port. Finding something listening here on a server is worth investigating, but there is no baseline reason for alarm.

How to Check What's Listening on This Port

On any Unix-like system:

# Show processes listening on port 3167
ss -tlnp sport = :3167

# Or with lsof
lsof -i :3167

# Or with netstat
netstat -anp | grep 3167

On Windows:

netstat -ano | findstr :3167
tasklist /FI "PID eq <PID from above>"

If something is listening here and you don't recognize it, check the process name against your installed software. An unknown listener on an obscure registered port is worth a closer look.

Why Unassigned-in-Practice Ports Matter

The registered ports range contains over 48,000 slots. Only a fraction of those have active, widely-used services. The rest are either legitimately assigned to niche or legacy applications (like this one), genuinely unassigned, or informally used by software that never bothered to register.

This matters for a few reasons:

• Firewall rules: Most firewalls block ports by default unless explicitly opened. An application that chooses an obscure registered port as its default often gets blocked by corporate or cloud security policies without clear explanation.
• Port conflicts: If your application tries to bind to 3167 and something else is already there, you'll get a binding error. Checking IANA first is good practice before choosing a port for new software.
• Security scanning: Automated scanners log open ports. A listener on an obscure port with no obvious justification stands out in a security audit.