Question 1

What is port 443 used for?

Accepted Answer

Port 443 is registered with the IANA for https (SCTP/TCP/UDP). Description: http protocol over TLS/SSL; HTTPS.

Question 2

Is port 443 a well-known port?

Accepted Answer

Yes. Port 443 is in the range 0–1023 (system or well-known ports). On Linux and macOS only privileged processes may bind to these ports.

Question 3

How do I check whether port 443 is open?

Accepted Answer

Locally on Linux with ss -tulpn | grep ':443\b', on Windows with netstat -ano | findstr :443. To test a remote host use Test-NetConnection -Port 443 in PowerShell or nc -zv 443 on Linux/macOS.

Question 4

How do I open port 443 in the firewall?

Accepted Answer

Ubuntu/Debian (ufw): sudo ufw allow 443/tcp. Fedora/RHEL (firewalld): sudo firewall-cmd --add-port=443/tcp --permanent, then firewall-cmd --reload. Windows (PowerShell as administrator): New-NetFirewallRule -DisplayName "Port 443" -Direction Inbound -Protocol TCP -LocalPort 443 -Action Allow.

Range	System/well-known port (0–1023)
Protocol	SCTP/TCP/UDP
Service	`https`
Reference	RFC 9110, RFC 9260
Modified	2022-02-07

Port 443

Frequently asked questions

What is port 443 used for?

Is port 443 a well-known port?

How do I check whether port 443 is open?

How do I open port 443 in the firewall?

IANA registry entries

Nearby entries

Protocol	Service	Description (IANA)
TCP	`https`	http protocol over TLS/SSL
UDP	`https`	http protocol over TLS/SSL
SCTP	`https`	HTTPS