WEBVTT 00:01.150 --> 00:03.490 Hello and welcome to this lecture. In this lecture 00:03.490 --> 00:09.430 We look at the networking configurations required on the master and worker nodes in a kubernetes cluster. 00:09.730 --> 00:15.610 The kubernetes cluster consists of master and worker nodes. Each node must have at least 1 interface 00:15.670 --> 00:17.170 connected to a network. 00:17.170 --> 00:19.750 Each interface must have an address configured. 00:19.750 --> 00:24.620 The hosts must have a unique hostname set. As well as a unique MAC address. 00:24.640 --> 00:29.750 You should note this especially if you created the VMs by cloning from existing ones. 00:29.830 --> 00:32.740 There are some ports that needs to be opened as well. 00:32.770 --> 00:35.550 These are used by the various components in the control plane. 00:35.590 --> 00:39.980 The master should accept connections on 6443 for the API server. 00:40.030 --> 00:45.850 The worker nodes, Kubectl tool, external users, and all other control plane components access the 00:45.850 --> 00:50.500 kube-api server via this port. The kubelets on the master and worker nodes listen on 00:50.500 --> 00:52.170 10250. Yes, 00:52.300 --> 00:57.050 in case we didn’t discuss this, the kubelet’s can be present on the master node as well. 00:57.070 --> 01:03.220 The kube-scheduler requires port 10251 to be open. The kube-controller-manager requires port 01:03.220 --> 01:10.180 10252 to be open. The worker nodes expose services for external access on ports 30000 to 01:10.180 --> 01:11.860 32767. 01:11.950 --> 01:13.270 So these should be open as well. 01:13.330 --> 01:17.260 Finally, the ETCD server listens on port 2379. 01:17.320 --> 01:23.020 If you have multiple master nodes, all of these ports need to be open on those as well. And you also need 01:23.020 --> 01:28.240 an additional port 2380 open so the ETCD clients can communicate with each other. 01:28.270 --> 01:33.430 The list of ports to be opened are also available in the kubernetes documentation page. 01:33.430 --> 01:39.430 So consider these when you setup networking for your nodes, in your firewalls, or ip table rules or network 01:39.430 --> 01:45.370 security group in a cloud environment such as GCP or Azure or AWS. And if things are not working 01:45.430 --> 01:50.530 this is one place to look for while you are investigating. Head over to the practice session and explore 01:50.530 --> 01:53.140 the networking setup in the existing environment. 01:53.140 --> 01:56.020 Keep this commands handy while you look for information. 01:56.050 --> 02:01.000 We will start with simple exercises where you will explore an existing kubernetes cluster and view 02:01.000 --> 02:05.040 information about the interfaces, ips, hostnames, ports etc. 02:05.050 --> 02:09.540 This will help you familiarize with the environment and look for information in the future sections. 02:09.550 --> 02:12.580 Going forward we will get into more challenging exercises. 02:12.640 --> 02:14.200 For now let's start slow.