Port 50
re-mail-ck · TCP/UDP
| Range | System/well-known port (0–1023) |
|---|---|
| Protocol | TCP/UDP |
| Service | re-mail-ck |
Frequently asked questions
What is port 50 used for?
Port 50 is registered with the IANA for re-mail-ck (TCP/UDP). Description: Remote Mail Checking Protocol.
Is port 50 a well-known port?
Yes. Port 50 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 50 is open?
Locally on Linux with ss -tulpn | grep ':50\b', on Windows with netstat -ano | findstr :50. To test a remote host use Test-NetConnection <host> -Port 50 in PowerShell or nc -zv <host> 50 on Linux/macOS.
How do I open port 50 in the firewall?
Ubuntu/Debian (ufw): sudo ufw allow 50/tcp. Fedora/RHEL (firewalld): sudo firewall-cmd --add-port=50/tcp --permanent, then firewall-cmd --reload. Windows (PowerShell as administrator): New-NetFirewallRule -DisplayName "Port 50" -Direction Inbound -Protocol TCP -LocalPort 50 -Action Allow.
IANA registry entries
| Protocol | Service | Description (IANA) |
|---|---|---|
| TCP | re-mail-ck | Remote Mail Checking Protocol |
| UDP | re-mail-ck | Remote Mail Checking Protocol |