Port 8443: HTTPS-alt
Port 8443 is the conventional alternate HTTPS port, used by admin consoles and application servers that cannot bind port 443. Worth knowing: IANA does not register it as alternate HTTPS at all. The registered service on TCP 8443 is pcsync-https.
| Port number | 8443 |
|---|---|
| Service | Alternate HTTPS |
| Protocol | TCP |
| Category | Web |
| Default encryption | Yes (TLS/SSH) |
| IANA service name | pcsync-https |
| IANA transports | TCP, UDP |
| Used in practice | TCP |
Is port 8443 HTTPS?
In practice, almost always yes: if something answers on 8443 it is normally a TLS-protected web interface. But that is convention, not specification. There is nothing in the protocol that makes 8443 HTTPS, and IANA's actual assignment for the number, pcsync-https, is unrelated to the way everyone uses it.
The practical consequence is that you must write the port into the URL. https://example.com:8443/ works; https://example.com/ goes to 443 and will fail if nothing is listening there. This is the single most common confusion around 8443.
It also means you should verify rather than assume. Something on 8443 could be plain HTTP, in which case a browser will report an error about the response not being valid TLS. A quick openssl s_client -connect host:8443 tells you whether a TLS handshake completes and what certificate is presented.
Which ports are related to port 8443?
The port a reader usually needs next is the encrypted or plaintext twin of this one, so those are listed first rather than buried in a generic list.
What commonly listens on port 8443?
- Apache Tomcat, whose default HTTPS connector uses 8443
- Firewall, hypervisor and appliance admin interfaces (pfSense, VMware, Sophos and similar)
- Kubernetes ingress controllers and application servers behind a load balancer
- Atlassian and other Java applications using the 8080 plus 8443 pairing
How do I check whether port 8443 is open?
Port 8443 carries TCP, so a connection either completes its handshake or it does not, which makes the check definitive.
| Question | Command | What to know |
|---|---|---|
| Is it open on a remote host? | nc -vz example.com 8443 | A TCP handshake either completes or it does not, so netcat gives a definitive answer in one line. |
| Same check on Windows | Test-NetConnection example.com -Port 8443 | Built into PowerShell. TcpTestSucceeded in the output is the answer; telnet is not installed by default on modern Windows. |
| What is listening locally? | ss -tlnp | grep ':8443 ' | Lists the process bound to port 8443 on Linux. On macOS use lsof -nP -iTCP:8443 -sTCP:LISTEN, on Windows netstat -ano | findstr :8443 |
Replace example.com with the host you are testing. A blocked port and a port with nothing listening on it look identical from the outside, so if a service should be running, check locally before blaming the firewall.
Frequently asked questions
What is port 8443 used for?
It is the conventional alternate HTTPS port, used for web admin interfaces and Java application servers such as Tomcat that cannot or should not bind the privileged port 443. It is not an IANA assignment for that purpose: the registry lists pcsync-https on TCP 8443.
Is port 8443 the same as 443?
Functionally similar, since both normally carry HTTPS, but not interchangeable. A browser assumes port 443 when a URL has no port, so 8443 must be written into the URL explicitly. And 443 is the registered https port while 8443 is registered to something else and used for HTTPS only by convention.
Is port 8443 secure?
It is as secure as the TLS configuration behind it, exactly like port 443. The port number provides no protection by itself. Because 8443 usually fronts an administrative interface, it is worth restricting by source address rather than exposing it to the internet.
Is port 8443 TCP or UDP?
IANA assigns port 8443 on TCP, UDP. In practice it carries TCP. This is the clearest example on the site of a registry entry that has nothing to do with real use. Every widespread use of 8443, from Tomcat to firewall admin interfaces, is convention rather than assignment, and the IANA name pcsync-https refers to an unrelated product.
Should I open port 8443 on my firewall?
Only if you specifically need HTTPS-alt. Expose it to the smallest set of trusted sources, and never open database or Windows-service ports to the whole internet.