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High port (10001–65535) High risk Community convention

Port 10250 KUBERNETES KUBELET

Quick answer

Port 10250 is the community default for Kubernetes kubelet, using TCP.

Check and block Is it safe? Troubleshooting FAQ
TransportTCP
RiskHigh
Typical useContainers and orchestration

What is port 10250 used for?

Port 10250 is widely used by Kubernetes kubelet (TCP), a community convention rather than an IANA assignment. Kubernetes kubelet HTTPS API port on each node (community convention; not IANA-assigned). It sits above the registered range, where most numbers are transient client ports. A fixed high port is worth documenting precisely because tooling often assumes the default.

Ports are the transport-layer address a service listens on. A client that wants to reach Kubernetes kubelet connects to port 10250. If nothing is listening, the connection is refused. That is why a port conflict appears whenever two processes try to bind the same number.

Use the commands below to confirm whether port 10250 is actually in use before you change firewall rules. Blocking the port stops new inbound traffic at the firewall, but it does not stop a local process from listening, and it does not remove the service from the machine.

Because this number is not IANA-assigned, a different application may legitimately use it on a machine you do not control. Always identify the actual listening process before deciding that the port belongs to this technology.

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This port number is not assigned by IANA. The entry documents a widely adopted community convention.

Check and block port 10250

Copy-ready commands for the protocols assigned to this port. Run the check first, then block only what should not be reachable.

Check on Linux

sudo ss -tlpn 'sport = :10250'

Check on Windows

Get-NetTCPConnection -LocalPort 10250 -State Listen -ErrorAction SilentlyContinue

Block with UFW

sudo ufw deny 10250/tcp

Block with iptables

sudo iptables -A INPUT -p tcp --dport 10250 -j DROP

These commands are examples for a typical host. Check the listener before you change firewall rules, and persist iptables rules with iptables-save or netfilter-persistent. On Windows, use Windows Defender Firewall or New-NetFirewallRule for persistent blocks. The iptables rules here cover IPv4; mirror them with ip6tables if IPv6 is enabled.

Is port 10250 safe to expose?

High

The kubelet API can execute commands inside pods. An unauthenticated kubelet is a cluster takeover vector; restrict it to the control plane. Treat this port as sensitive. Restrict it to trusted networks or a VPN, require authentication and logging, and never expose it directly to the public internet without a hardened gateway in front.

Where port 10250 is usually used

Most traffic on port 10250 falls into these scenarios. The demo below is a safe way to confirm the listener before you change anything.

Demo

Probe the kubelet API

The kubelet requires authentication; this only confirms the HTTPS port is reachable from a trusted host.

nc -vz 127.0.0.1 10250

Common problems with port 10250

Connection refused or timed out

Refused usually means the host is reachable but nothing is listening on port 10250. A timeout more often means a firewall drop, a wrong host or a service bound to a different interface.

Port already in use

Find the process holding the port with sudo ss -tlpn 'sport = :10250' or sudo lsof -i :10250. Stop that process or configure it to bind another port; killing it without identifying it can take down a production service.

Firewall rule did not survive a reboot

UFW and Windows Firewall keep rules across restarts. Raw iptables rules do not: save them with iptables-save or the netfilter-persistent package, and re-apply after upgrades that reset the ruleset.

The port is blocked but still reachable

A firewall rule filters inbound traffic; it does not close the listener. Confirm with the check command above and bind the service to 127.0.0.1 when only local clients need it.

Port 10250 at a glance

Port number10250
Service nameKubernetes kubelet
Transport protocolTCP
CategoryContainers and orchestration
RangeHigh port (10001–65535)
Risk levelHigh
ReferenceCommunity convention (not IANA-assigned)
Registry descriptionKubernetes kubelet HTTPS API port on each node (community convention; not IANA-assigned)
SourceCommunity convention

Frequently asked questions

What is port 10250 used for?

Port 10250 (KUBERNETES KUBELET) uses TCP. Kubernetes kubelet HTTPS API port on each node (community convention; not IANA-assigned) (community convention, not an IANA assignment).

How do I check if port 10250 is open?

On Linux run `sudo ss -tlpn 'sport = :10250'`. On Windows run `Get-NetTCPConnection -LocalPort 10250 -State Listen -ErrorAction SilentlyContinue` in PowerShell. If the port is open, the output shows a process listening on port 10250; empty output usually means nothing is bound to it.

How do I block port 10250?

With UFW run `sudo ufw deny 10250/tcp`. With iptables run `sudo iptables -A INPUT -p tcp --dport 10250 -j DROP`. Persist the iptables rules with your distribution's netfilter-persistent or iptables-save tooling so they survive a reboot.

Is port 10250 safe to expose?

The kubelet API can execute commands inside pods. An unauthenticated kubelet is a cluster takeover vector; restrict it to the control plane. Nevertheless, treat this port as sensitive. Restrict it to trusted networks or a VPN, require authentication and logging, and never expose it directly to the public internet without a hardened gateway in front.

See all Containers and orchestration ports

Primary data: IANA Service Name and Transport Protocol Port Number Registry. This number is a community convention, not an IANA assignment.

Last reviewed 2026-10-30 · Methodology · About · Privacy