Port 638
mcns-sec · TCP/UDP
| Range | System/well-known port (0–1023) |
|---|---|
| Protocol | TCP/UDP |
| Service | mcns-sec |
Frequently asked questions
What is port 638 used for?
Port 638 is registered with the IANA for mcns-sec (TCP/UDP). Description: mcns-sec.
Is port 638 a well-known port?
Yes. Port 638 is in the range 0–1023 (system or well-known ports). On Linux and macOS only privileged processes may bind to these ports.
How do I check whether port 638 is open?
Locally on Linux with ss -tulpn | grep ':638\b', on Windows with netstat -ano | findstr :638. To test a remote host use Test-NetConnection <host> -Port 638 in PowerShell or nc -zv <host> 638 on Linux/macOS.
How do I open port 638 in the firewall?
Ubuntu/Debian (ufw): sudo ufw allow 638/tcp. Fedora/RHEL (firewalld): sudo firewall-cmd --add-port=638/tcp --permanent, then firewall-cmd --reload. Windows (PowerShell as administrator): New-NetFirewallRule -DisplayName "Port 638" -Direction Inbound -Protocol TCP -LocalPort 638 -Action Allow.
IANA registry entries
| Protocol | Service | Description (IANA) |
|---|---|---|
| TCP | mcns-sec | mcns-sec |
| UDP | mcns-sec | mcns-sec |