Port 8883: MQTTS
Port 8883 is MQTT encrypted with TLS, used when IoT devices need to authenticate to the broker and protect message contents in transit. It is the secure counterpart to plain MQTT on port 1883.
| Port number | 8883 |
|---|---|
| Service | MQTT over TLS |
| Protocol | TCP |
| Category | IoT & automation |
| Default encryption | Yes (TLS/SSH) |
How do I check whether port 8883 is open?
Port 8883 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 8883 | 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 8883 | 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 ':8883 ' | Lists the process bound to port 8883 on Linux. On macOS use lsof -nP -iTCP:8883 -sTCP:LISTEN, on Windows netstat -ano | findstr :8883 |
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 8883 used for?
Port 8883 is MQTT encrypted with TLS, used when IoT devices need to authenticate to the broker and protect message contents in transit. It is the secure counterpart to plain MQTT on port 1883.
Is port 8883 TCP or UDP?
Port 8883 (MQTTS) uses TCP.
Is port 8883 secure?
Yes. Port 8883 carries encrypted traffic by default, so data in transit is protected.
Should I open port 8883 on my firewall?
Only if you specifically need MQTTS. Expose it to the smallest set of trusted sources, and never open database or Windows-service ports to the whole internet.