I have a k8s cluster, and there are some ports which are exposed by kube-proxy such as 31381 and 31382.
[root@rg1-ostack219 leo]# hostname -I | awk '{print $1}'
10.211.85.97
[root@rg1-ostack219 leo]# netstat -anp |grep " LISTEN "
tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN 21156/sshd
tcp 0 0 127.0.0.1:10009 0.0.0.0:* LISTEN 90833/scribed
tcp 0 0 127.0.0.1:25 0.0.0.0:* LISTEN 3006/master
tcp 0 0 0.0.0.0:16509 0.0.0.0:* LISTEN 2207/libvirtd
tcp 0 0 127.0.0.1:33123 0.0.0.0:* LISTEN 89258/kubelet
tcp 0 0 127.0.0.1:10248 0.0.0.0:* LISTEN 89258/kubelet
tcp 0 0 0.0.0.0:52360 0.0.0.0:* LISTEN 2464/hooagent
tcp 0 0 127.0.0.1:10249 0.0.0.0:* LISTEN 64755/kube-proxy
tcp 0 0 0.0.0.0:6666 0.0.0.0:* LISTEN 97587/ssh
tcp 0 0 127.0.0.1:10251 0.0.0.0:* LISTEN 90172/kube-schedule
tcp 0 0 127.0.0.1:2379 0.0.0.0:* LISTEN 90052/etcd
tcp 0 0 10.211.85.97:2379 0.0.0.0:* LISTEN 90052/etcd
tcp 0 0 127.0.0.1:10252 0.0.0.0:* LISTEN 89938/kube-controll
tcp 0 0 10.211.85.97:2380 0.0.0.0:* LISTEN 90052/etcd
tcp 0 0 0.0.0.0:111 0.0.0.0:* LISTEN 1675/rpcbind
tcp6 1 0 :::31381 :::* LISTEN 64755/kube-proxy
tcp6 0 0 :::31413 :::* LISTEN 64755/kube-proxy
tcp6 0 0 :::31382 :::* LISTEN 64755/kube-proxy
tcp6 0 0 :::31830 :::* LISTEN 64755/kube-proxy
tcp6 0 0 :::22 :::* LISTEN 21156/sshd
tcp6 0 0 :::32026 :::* LISTEN 64755/kube-proxy
tcp6 0 0 :::443 :::* LISTEN 91307/traefik
tcp6 0 0 :::32541 :::* LISTEN 64755/kube-proxy
tcp6 0 0 :::31485 :::* LISTEN 64755/kube-proxy
tcp6 0 0 :::31390 :::* LISTEN 64755/kube-proxy
tcp6 0 0 :::31392 :::* LISTEN 64755/kube-proxy
tcp6 0 0 :::30692 :::* LISTEN 64755/kube-proxy
tcp6 0 0 :::31400 :::* LISTEN 64755/kube-proxy
tcp6 0 0 :::6666 :::* LISTEN 97587/ssh
tcp6 0 0 :::10250 :::* LISTEN 89258/kubelet
tcp6 0 0 :::6443 :::* LISTEN 89836/kube-apiserve
tcp6 0 0 :::9100 :::* LISTEN 50266/node_exporter
tcp6 0 0 :::111 :::* LISTEN 1675/rpcbind
tcp6 0 0 :::8080 :::* LISTEN 91307/traefik
tcp6 0 0 :::80 :::* LISTEN 91307/traefik
tcp6 0 0 :::10256 :::* LISTEN 64755/kube-proxy
tcp6 0 0 :::10257 :::* LISTEN 89938/kube-controll
tcp6 0 0 :::32116 :::* LISTEN 64755/kube-proxy
tcp6 1 0 :::31380 :::* LISTEN 64755/kube-proxyThe problem is When I run telnet 10.211.85.97 31381 and telnet 127.0.0.1 6443, everything is ok, but when I run telnet 127.0.0.1 31381, there is no any response.
It doesn't listen on the same localhost the is connected to your hypervisor host machine. Each kube-proxy service proxy gets its own cluster IP that functions like a container would more or less, though with more iptables magic usually.