Port 406
imsp · TCP/UDP
| Range | System/well-known port (0–1023) |
|---|---|
| Protocol | TCP/UDP |
| Service | imsp |
Frequently asked questions
What is port 406 used for?
Port 406 is registered with the IANA for imsp (TCP/UDP). Description: Interactive Mail Support Protocol.
Is port 406 a well-known port?
Yes. Port 406 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 406 is open?
Locally on Linux with ss -tulpn | grep ':406\b', on Windows with netstat -ano | findstr :406. To test a remote host use Test-NetConnection <host> -Port 406 in PowerShell or nc -zv <host> 406 on Linux/macOS.
How do I open port 406 in the firewall?
Ubuntu/Debian (ufw): sudo ufw allow 406/tcp. Fedora/RHEL (firewalld): sudo firewall-cmd --add-port=406/tcp --permanent, then firewall-cmd --reload. Windows (PowerShell as administrator): New-NetFirewallRule -DisplayName "Port 406" -Direction Inbound -Protocol TCP -LocalPort 406 -Action Allow.
IANA registry entries
| Protocol | Service | Description (IANA) |
|---|---|---|
| TCP | imsp | Interactive Mail Support Protocol |
| UDP | imsp | Interactive Mail Support Protocol |