Port 143
imap · TCP/UDP
| Range | System/well-known port (0–1023) |
|---|---|
| Protocol | TCP/UDP |
| Service | imap |
| Reference | RFC 3501, RFC 9051, RFC 9051 |
| Modified | 2021-02-22 |
Frequently asked questions
What is port 143 used for?
Port 143 is registered with the IANA for imap (TCP/UDP). Description: Internet Message Access Protocol; Reserved.
Is port 143 a well-known port?
Yes. Port 143 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 143 is open?
Locally on Linux with ss -tulpn | grep ':143\b', on Windows with netstat -ano | findstr :143. To test a remote host use Test-NetConnection <host> -Port 143 in PowerShell or nc -zv <host> 143 on Linux/macOS.
How do I open port 143 in the firewall?
Ubuntu/Debian (ufw): sudo ufw allow 143/tcp. Fedora/RHEL (firewalld): sudo firewall-cmd --add-port=143/tcp --permanent, then firewall-cmd --reload. Windows (PowerShell as administrator): New-NetFirewallRule -DisplayName "Port 143" -Direction Inbound -Protocol TCP -LocalPort 143 -Action Allow.
IANA registry entries
| Protocol | Service | Description (IANA) |
|---|---|---|
| TCP | imap | Internet Message Access Protocol |
| UDP | – | Reserved |