Port 512
biff, comsat and exec · TCP/UDP
| Range | System/well-known port (0–1023) |
|---|---|
| Protocol | TCP/UDP |
| Service | biff, comsat and exec |
Frequently asked questions
What is port 512 used for?
Port 512 is registered with the IANA for biff, comsat and exec (TCP/UDP). Description: remote process execution; authentication performed using passwords and UNIX login names; ; used by mail system to notify users of new mail received; currently receives messages only from processes on the same machine.
Is port 512 a well-known port?
Yes. Port 512 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 512 is open?
Locally on Linux with ss -tulpn | grep ':512\b', on Windows with netstat -ano | findstr :512. To test a remote host use Test-NetConnection <host> -Port 512 in PowerShell or nc -zv <host> 512 on Linux/macOS.
How do I open port 512 in the firewall?
Ubuntu/Debian (ufw): sudo ufw allow 512/tcp. Fedora/RHEL (firewalld): sudo firewall-cmd --add-port=512/tcp --permanent, then firewall-cmd --reload. Windows (PowerShell as administrator): New-NetFirewallRule -DisplayName "Port 512" -Direction Inbound -Protocol TCP -LocalPort 512 -Action Allow.
IANA registry entries
| Protocol | Service | Description (IANA) |
|---|---|---|
| TCP | exec | remote process execution; authentication performed using passwords and UNIX login names |
| UDP | comsat | |
| UDP | biff | used by mail system to notify users of new mail received; currently receives messages only from processes on the same machine |