What uses port 2379
etcd is the key-value store that holds all Kubernetes cluster state, including Secrets. The API server talks to it on 2379; etcd members replicate to each other on 2380. Read access to etcd is effectively full control of the cluster, so it must use client certificate authentication and be reachable only from control-plane nodes.
Should port 2379 be open to the internet?
Keep private. Never expose this port to the internet. Keep it on localhost, a private network or behind a VPN or SSH tunnel.
Check what is listening on port 2379
sudo ss -ltnp 'sport = :2379'sudo lsof -nP -iTCP:2379 -sTCP:LISTENGet-NetTCPConnection -LocalPort 2379 -State Listen
netstat -ano | findstr :2379No output means nothing is listening. If a service should be, check that it is running and which address it binds to: 127.0.0.1 only accepts local connections, 0.0.0.0 or :: accepts them on every interface.
Fix “address already in use” on port 2379
Another process already holds the port. Find it with the commands above, then stop that service properly, or end the process:
sudo kill $(sudo lsof -t -iTCP:2379 -sTCP:LISTEN)Stop-Process -Id (Get-NetTCPConnection -LocalPort 2379 -State Listen).OwningProcessAllow port 2379 from trusted networks only
The examples allow 2379 only from 10.0.0.0/8; replace it with your own private network, office IP or VPN range.
sudo ufw allow from 10.0.0.0/8 to any port 2379 proto tcp
# Close it again:
sudo ufw delete allow from 10.0.0.0/8 to any port 2379 proto tcpsudo firewall-cmd --permanent --add-rich-rule='rule family="ipv4" source address="10.0.0.0/8" port port="2379" protocol="tcp" accept'
sudo firewall-cmd --reloadNew-NetFirewallRule -DisplayName "etcd client 2379/TCP" -Direction Inbound -Protocol TCP -LocalPort 2379 -Action Allow -RemoteAddress 10.0.0.0/8On AWS, Google Cloud and Azure, also allow the port in the security group or network firewall rules; host firewalls and cloud firewalls are separate.
Test port 2379 from another machine
nc -zv example.com 2379Test-NetConnection example.com -Port 2379Related ports
- Port 2380 (etcd peer): used for replication between etcd cluster members.
- Port 6443 (Kubernetes API server): the default port of the Kubernetes API server.
- Port 10250 (Kubelet API): the kubelet API on every Kubernetes node.
More containers and orchestration ports
2375 (Docker API (unencrypted)) , 2376 (Docker API (TLS)) . See all ports in the port lookup.
Sources
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Frequently asked questions
What is port 2379 used for?
Port 2379 is the etcd client API port, used by the Kubernetes API server. etcd is the key-value store that holds all Kubernetes cluster state, including Secrets. The API server talks to it on 2379; etcd members replicate to each other on 2380. Read access to etcd is effectively full control of the cluster, so it must use client certificate authentication and be reachable only from control-plane nodes.
Is it safe to open port 2379?
Never expose this port to the internet. Keep it on localhost, a private network or behind a VPN or SSH tunnel. Allow it only from the networks that need it, as in the firewall examples on this page.
How do I check if port 2379 is open?
On the server, list listening sockets with "sudo ss -ltnp 'sport = :2379'" on Linux or "sudo lsof -nP -i :2379" on macOS. From another machine, run "nc -zv host 2379" or, on Windows, "Test-NetConnection host -Port 2379". Connection refused means nothing is listening; a timeout means a firewall is dropping the traffic.