Port 10250: Kubelet
Port 10250 is the kubelet API, exposed by the agent that runs on every Kubernetes node to manage the containers scheduled there. It has been the target of real-world attacks when left unauthenticated, so securing it is a standard cluster-hardening step.
| Port number | 10250 |
|---|---|
| Service | Kubernetes kubelet API |
| Protocol | TCP |
| Category | Infrastructure & orchestration |
| Default encryption | No |
How do I check whether port 10250 is open?
Port 10250 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 10250 | 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 10250 | 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 ':10250 ' | Lists the process bound to port 10250 on Linux. On macOS use lsof -nP -iTCP:10250 -sTCP:LISTEN, on Windows netstat -ano | findstr :10250 |
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 10250 used for?
Port 10250 is the kubelet API, exposed by the agent that runs on every Kubernetes node to manage the containers scheduled there. It has been the target of real-world attacks when left unauthenticated, so securing it is a standard cluster-hardening step.
Is port 10250 TCP or UDP?
Port 10250 (Kubelet) uses TCP.
Is port 10250 secure?
Port 10250 is not encrypted by default. Where possible, use an encrypted alternative or tunnel it over TLS or a VPN.
Should I open port 10250 on my firewall?
Only if you specifically need Kubelet. Expose it to the smallest set of trusted sources, and never open database or Windows-service ports to the whole internet.