Port Number Reference
Look up what service uses a port — and which ports should never face the internet.
System verdict
RESULTPort 443 — HTTPS
Encrypted web traffic. The default for essentially every modern site. Remember that a port’s registered service is a convention — it does not prove what is actually listening there.
- Port
- 443
- Service
- HTTPS
- Protocol
- TCP
What this cannot tell you
- A reference of common assignments, not a scan. Knowing a port’s registered service does not tell you what is actually listening on it — any service can use any port.
- Port assignments drift and many are used unofficially. Treat this as a convention guide, not proof.
- It does not check your ports. It cannot see your machine or network — it only explains what a port number conventionally means.
How this calculation works
Enter a port number or a service name. The tool returns the conventional service, the protocol, and a note — and flags the ports, like RDP, SMB and the database ports, that are dangerous to expose to the internet.
What the results mean
- Well-known ports (0–1023)
- Reserved for core services — HTTP, SSH, DNS and the like. Assigned by IANA.
- Registered ports (1024–49151)
- Assigned to specific applications, but far less strictly. Many overlap in practice.
- Risky when exposed
- Database ports (3306, 5432, 27017), remote access (3389 RDP, 445 SMB) and unauthenticated stores (6379 Redis) should never be reachable from the internet.
Frequently asked questions
Does an open port mean I have been hacked?
No. An open port just means a service is listening, which is normal — a web server listens on 443, for instance. The risk is specific ports being reachable from the internet when they should only be local, especially databases and remote-desktop. This tool explains which those are; it cannot see your machine.
Can a service run on a non-standard port?
Yes, entirely. Any service can listen on any port, and many deliberately move off the defaults. That is exactly why a port lookup tells you the convention, not the reality — the only way to know what is truly running is to check the machine itself.
Why is port 443 so important?
It carries HTTPS — encrypted web traffic — and is the default for essentially every modern website. Port 80 (plain HTTP) still exists mostly to redirect visitors to 443.