Port 4881
socp-t · TCP/UDP
| Range | Registered port (1024–49151) |
|---|---|
| Protocol | TCP/UDP |
| Service | socp-t |
| Registered | 2010-05-28 |
Frequently asked questions
What is port 4881 used for?
Port 4881 is registered with the IANA for socp-t (TCP/UDP). Description: Reserved; SOCP Time Synchronization Protocol.
Is port 4881 a well-known port?
No. Port 4881 is in the range 1024–49151 (registered or user ports). Ordinary programs may open it without root privileges.
How do I check whether port 4881 is open?
Locally on Linux with ss -tulpn | grep ':4881\b', on Windows with netstat -ano | findstr :4881. To test a remote host use Test-NetConnection <host> -Port 4881 in PowerShell or nc -zv <host> 4881 on Linux/macOS.
How do I open port 4881 in the firewall?
Ubuntu/Debian (ufw): sudo ufw allow 4881/tcp. Fedora/RHEL (firewalld): sudo firewall-cmd --add-port=4881/tcp --permanent, then firewall-cmd --reload. Windows (PowerShell as administrator): New-NetFirewallRule -DisplayName "Port 4881" -Direction Inbound -Protocol TCP -LocalPort 4881 -Action Allow.
IANA registry entries
| Protocol | Service | Description (IANA) |
|---|---|---|
| TCP | – | Reserved |
| UDP | socp-t | SOCP Time Synchronization Protocol |