关于 Kubernetes中NetworkPolicy(网络策略)方面的一些笔记

写在前面

学习k8s遇到整理笔记
博文内容主要涉及
Kubernetes网络策略理论简述
K8s中网络策略方式：egress和ingress的Demo
ipBlock,namespaceSelector,podSelector的网络策略规则Demo

混吃等死，小富即安，飞黄腾达，是因为各有各的缘法，未必有高下之分。–—烽火戏诸侯《剑来》

Kubernetes网络策略

为了实现细粒度的容器间网络访问隔离策略(防火墙), Kubernetes从1.3版本开始,由SIG-Network小组主导研发了Network Policy机制,目前已升级为networking.k8s.io/v1稳定版本。

Network Policy的主要功能是对Pod间的网络通信进行限制和准入控制

设置方式为将Pod的Label作为查询条件,设置允许访问或禁止访问的客户端Pod列表。查询条件可以作用于Pod和Namespace级别。

为了使用Network Policy, Kubernetes引入了一个新的资源对象NetworkPolicy,供用户设置Pod间网络访问的策略。但仅定义一个网络策略是无法完成实际的网络隔离的,还需要一个策略控制器(PolicyController)进行策略的实现。

策略控制器由第三方网络组件提供,目前Calico, Cilium, Kube-router, Romana, Weave Net等开源项目均支持网络策略的实现。Network Policy的工作原理如图

policy controller需要实现一个API Listener,监听用户设置的NetworkPolicy定义,并将网络访问规则通过各Node的Agent进行实际设置(Agent则需要通过CNI网络插件实现)

网络策略配置说明

网络策略的设置主要用于对目标Pod的网络访问进行限制,在默认·情况下对所有Pod都是允许访问的,在设置了指向Pod的NetworkPolicy网络策略之后,到Pod的访问才会被限制。 需要注意的是网络策略是基于Pod的

NetWorkPolicy基于命名空间进行限制，即只作用当前命名空间，分为两种：

ingress:定义允许访问目标Pod的入站白名单规则
egress: 定义目标Pod允许访问的“出站”白名单规则

具体的规则限制方式分为三种(需要注意的是，多个限制之间是或的逻辑关系,如果希望变成与的关系，yaml文件需要配置为数组)：

IP 策略
命名空间策略
pod选择器限制

下面是一个资源文件的Demo

apiVersion: networking.k8s.io/v1
kind: NetworkPolicy
metadata:name: test-network-policynamespace: default
spec:podSelector: #用于定义该网络策略作用的Pod范围matchLabels:role: dbpolicyTypes: #网络策略的类型，包括ingress和egress两种- Ingress- Egressingress: #定义允许访问目标Pod的入站白名单规则- from: #满足from 条件的客户端才能访问ports定义的目标Pod端口号。- ipBlock: # IP限制cidr: 172.17.0.0/16except:  #排除那些IP- 172.17.1.0/24- namespaceSelector:  #命名空间限制matchLabels:project: myproject- podSelector:  # pod选择器限制matchLabels:role: frontendports: #允许访问的目标Pod监听的端口号。- protocol: TCPport: 6379egress: #定义目标Pod允许访问的“出站”白名单规则- to: #目标Pod仅允许访问满足to条件的服务端IP范围和ports定义的端口号- ipBlock:cidr: 10.0.0.0/24ports:  #允许访问的服务端的端口号。- protocol: TCPport: 5978

在Namespace级别设置默认的网络策略

在Namespace级别还可以设置一些默认的全局网络策略,以方便管理员对整个Namespace进行统一的网络策略设置。

默认拒绝所有入站流量

apiVersion: networking.k8s.io/v1
kind: NetworkPolicy
metadata:name: default-deny-ingress
spec:podSelector: {}policyTypes:- Ingress

默认允许所有入站流量

apiVersion: networking.k8s.io/v1
kind: NetworkPolicy
metadata:name: allow-all-ingress
spec:podSelector: {}ingress:- {}policyTypes:- Ingress

默认拒绝所有出站流量

apiVersion: networking.k8s.io/v1
kind: NetworkPolicy
metadata:name: default-deny-egress
spec:podSelector: {}policyTypes:- Egress

默认允许所有出站流量

apiVersion: networking.k8s.io/v1
kind: NetworkPolicy
metadata:name: allow-all-egress
spec:podSelector: {}egress:- {}policyTypes:- Egress

默认拒绝所有入口和所有出站流量

apiVersion: networking.k8s.io/v1
kind: NetworkPolicy
metadata:name: default-deny-all
spec:podSelector: {}policyTypes:- Ingress- Egress

NetworkPolicy的发展

作为一个稳定特性，SCTP支持默认是被启用的。要在集群层面禁用 SCTP，你（或你的集群管理员）需要为API服务器指定 --feature-gates=SCTPSupport=false,… 来禁用 SCTPSupport特性门控。启用该特性门控后，用户可以将 NetworkPolicy 的protocol字段设置为 SCTP(不同版本略有区别)

NetWorkPolicy实战

环境准备

先创建两个没有任何策略的SVC

┌──[root@vms81.liruilongs.github.io]-[~/ansible]
└─$d=k8s-network-create
┌──[root@vms81.liruilongs.github.io]-[~/ansible]
└─$mkdir $d;cd $d
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-network-create]
└─$kubectl  create  ns liruilong-network-create
namespace/liruilong-network-create created
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-network-create]
└─$kubectl  config  set-context  $(kubectl config current-context) --namespace=liruilong-network-createContext "kubernetes-admin@kubernetes" modified.
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-network-create]
└─$kubectl  config view | grep namespacenamespace: liruilong-network-create
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-network-create]
└─$

我们先构造两个pod,为两个SVC提供能力

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-network-create]
└─$kubectl  run pod1 --image=nginx --image-pull-policy=IfNotPresent
pod/pod1 created
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-network-create]
└─$kubectl  run pod2 --image=nginx --image-pull-policy=IfNotPresent
pod/pod2 created
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-network-create]
└─$kubectl  get pods -o wide
NAME   READY   STATUS    RESTARTS   AGE   IP               NODE                         NOMINATED NODE   READINESS GATES
pod1   1/1     Running   0          35s   10.244.70.31     vms83.liruilongs.github.io   <none>           <none>
pod2   1/1     Running   0          21s   10.244.171.181   vms82.liruilongs.github.io   <none>           <none>
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-network-create]
└─$

然后我们分别修改pod中Ngixn容器主页

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-network-create]
└─$kubectl  get pods  --show-labels
NAME   READY   STATUS    RESTARTS   AGE    LABELS
pod1   1/1     Running   0          100s   run=pod1
pod2   1/1     Running   0          86s    run=pod2
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-network-create]
└─$kubectl  exec  -it pod1 -- sh -c "echo pod1 >/usr/share/nginx/html/index.html"
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-network-create]
└─$kubectl  exec  -it pod2 -- sh -c "echo pod2 >/usr/share/nginx/html/index.html"

创建两个SVC

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-network-create]
└─$kubectl  expose  --name=svc1 pod pod1 --port=80 --type=LoadBalancer
service/svc1 exposed
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-network-create]
└─$kubectl  expose  --name=svc2 pod pod2 --port=80 --type=LoadBalancer
service/svc2 exposed
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-network-create]
└─$kubectl  get svc
NAME   TYPE           CLUSTER-IP       EXTERNAL-IP      PORT(S)        AGE
svc1   LoadBalancer   10.106.61.84     192.168.26.240   80:30735/TCP   14s
svc2   LoadBalancer   10.111.123.194   192.168.26.241   80:31034/TCP   5s
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-network-create]
└─$

访问测试，无论在当前命名空间还是在指定命名空间，都可以相互访问

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-network-create]
└─$kubectl  run testpod1 -it --rm --image=yauritux/busybox-curl --image-pull-policy=IfNotPresent
If you don''t see a command prompt, try pressing enter.
/home # curl svc1
pod1
/home # curl svc2
pod2
/home # exit

指定命名空间

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-network-create]
└─$kubectl  run testpod2 -it --rm --image=yauritux/busybox-curl --image-pull-policy=IfNotPresent -n default
If you don''t see a command prompt, try pressing enter.
/home # curl svc1.liruilong-network-create
pod1
/home # curl svc2.liruilong-network-create
pod2
/home #

由于使用了LB，所以物理机也可以访问

PS E:\docker> curl 192.168.26.240   StatusCode        : 200
StatusDescription : OK
Content           : pod1RawContent        : HTTP/1.1 200 OKConnection: keep-aliveAccept-Ranges: bytesContent-Length: 5Content-Type: text/htmlDate: Mon, 03 Jan 2022 12:29:32 GMTETag: "61d27744-5"Last-Modified: Mon, 03 Jan 2022 04:1...
Forms             : {}
Headers           : {[Connection, keep-alive], [Accept-Ranges, bytes], [Content-Length, 5], [Content-Type, text/html]...}
Images            : {}
InputFields       : {}
Links             : {}
ParsedHtml        : System.__ComObject
RawContentLength  : 5

PS E:\docker> curl 192.168.26.241StatusCode        : 200
StatusDescription : OK
Content           : pod2RawContent        : HTTP/1.1 200 OKConnection: keep-aliveAccept-Ranges: bytesContent-Length: 5Content-Type: text/htmlDate: Mon, 03 Jan 2022 12:29:49 GMTETag: "61d27752-5"Last-Modified: Mon, 03 Jan 2022 04:1...
Forms             : {}
Headers           : {[Connection, keep-alive], [Accept-Ranges, bytes], [Content-Length, 5], [Content-Type, text/html]...}
Images            : {}
InputFields       : {}
Links             : {}
ParsedHtml        : System.__ComObject
RawContentLength  : 5
PS E:\docker>

进入策略

下面我们看一下进入的策略

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-network-create]
└─$kubectl  get pods --show-labels
NAME   READY   STATUS    RESTARTS        AGE    LABELS
pod1   1/1     Running   2 (3d12h ago)   5d9h   run=pod1
pod2   1/1     Running   2 (3d12h ago)   5d9h   run=pod2
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-network-create]
└─$kubectl  get svc -o wide
NAME   TYPE           CLUSTER-IP       EXTERNAL-IP      PORT(S)        AGE    SELECTOR
svc1   LoadBalancer   10.106.61.84     192.168.26.240   80:30735/TCP   5d9h   run=pod1
svc2   LoadBalancer   10.111.123.194   192.168.26.241   80:31034/TCP   5d9h   run=pod2
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-network-create]
└─$

测试的外部物理机机器IP

PS E:\docker> ipconfigWindows IP 配置
..........以太网适配器 VMware Network Adapter VMnet8:连接特定的 DNS 后缀 . . . . . . . :本地链接 IPv6 地址. . . . . . . . : fe80::f9c8:e941:4deb:698f%24IPv4 地址 . . . . . . . . . . . . : 192.168.26.1子网掩码  . . . . . . . . . . . . : 255.255.255.0默认网关. . . . . . . . . . . . . :

IP限制

我们通过修改ip限制来演示网路策略，通过宿主机所在物理机访问。当设置指定网段可以访问，不是指定网段不可以访问

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-network-create]
└─$vim networkpolicy.yaml
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-network-create]
└─$kubectl  apply -f networkpolicy.yaml
networkpolicy.networking.k8s.io/test-network-policy configured

编写资源文件，允许172.17.0.0/16网段的机器访问

apiVersion: networking.k8s.io/v1
kind: NetworkPolicy
metadata:name: test-network-policynamespace: liruilong-network-create
spec:podSelector:matchLabels:run: pod1policyTypes:- Ingressingress:- from:- ipBlock:cidr: 172.17.0.0/16 #  只允许这个网段访问ports:- protocol: TCPport: 80

集群外部机器无法访问

PS E:\docker> curl 192.168.26.240
curl : 无法连接到远程服务器
所在位置 行:1 字符: 1
+ curl 192.168.26.240
+ ~~~~~~~~~~~~~~~~~~~+ CategoryInfo          : InvalidOperation: (System.Net.HttpWebRequest:HttpWebRequest) [Invoke-WebRequest]，WebException+ FullyQualifiedErrorId : WebCmdletWebResponseException,Microsoft.PowerShell.Commands.InvokeWebRequestCommand

配置允许当前网段的ip访问

apiVersion: networking.k8s.io/v1
kind: NetworkPolicy
metadata:name: test-network-policynamespace: liruilong-network-create
spec:podSelector:matchLabels:run: pod1policyTypes:- Ingressingress:- from:- ipBlock:cidr: 192.168.26.0/24 #  只允许这个网段访问ports:- protocol: TCPport: 80

修改网段之后正常外部机器可以访问

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-network-create]
└─$sed -i 's#172.17.0.0/16#192.168.26.0/24#' networkpolicy.yaml
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-network-create]
└─$kubectl  apply -f networkpolicy.yaml

测试，外部机器可以访问

PS E:\docker> curl 192.168.26.240StatusCode        : 200
StatusDescription : OK
Content           : pod1RawContent        : HTTP/1.1 200 OKConnection: keep-aliveAccept-Ranges: bytesContent-Length: 5Content-Type: text/htmlDate: Sat, 08 Jan 2022 14:59:13 GMTETag: "61d9a663-5"Last-Modified: Sat, 08 Jan 2022 14:5...
Forms             : {}
Headers           : {[Connection, keep-alive], [Accept-Ranges, bytes], [Content-Length, 5], [Content-Type, text/html]...}
Images            : {}
InputFields       : {}
Links             : {}
ParsedHtml        : System.__ComObject
RawContentLength  : 5

命名空间限制

设置只允许default命名空间的数据通过

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-network-create]
└─$kubectl  get ns --show-labels  | grep default
default                      Active   26d     kubernetes.io/metadata.name=default
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-network-create]
└─$vim networkpolicy-name.yaml
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-network-create]
└─$kubectl apply -f  networkpolicy-name.yaml
networkpolicy.networking.k8s.io/test-network-policy configured

apiVersion: networking.k8s.io/v1
kind: NetworkPolicy
metadata:name: test-network-policynamespace: liruilong-network-create
spec:podSelector:matchLabels:run: pod1policyTypes:- Ingressingress:- from:- namespaceSelector:matchLabels:kubernetes.io/metadata.name: defaultports:- protocol: TCPport: 80

宿主机所在物理机无法访问访问

PS E:\docker> curl 192.168.26.240
curl : 无法连接到远程服务器
所在位置 行:1 字符: 1
+ curl 192.168.26.240
+ ~~~~~~~~~~~~~~~~~~~+ CategoryInfo          : InvalidOperation: (System.Net.HttpWebRequest:HttpWebRequest) [Invoke-WebRequest]，WebException+ FullyQualifiedErrorId : WebCmdletWebResponseException,Microsoft.PowerShell.Commands.InvokeWebRequestCommandPS E:\docker>

当前命名空间也无法访问

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-network-create]
└─$kubectl  run testpod1 -it --rm --image=yauritux/busybox-curl --image-pull-policy=IfNotPresent/home # curl --connect-timeout 10 -m 10 svc1
curl: (28) Connection timed out after 10413 milliseconds

default命名空间可以访问

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-network-create]
└─$kubectl  run testpod1 -it --rm --image=yauritux/busybox-curl --image-pull-policy=IfNotPresent --namespace=default/home # curl  --connect-timeout 10 -m 10 svc1.liruilong-network-create
pod1
/home #

pod选择器限制

apiVersion: networking.k8s.io/v1
kind: NetworkPolicy
metadata:name: test-network-policynamespace: liruilong-network-create
spec:podSelector:matchLabels:run: pod1policyTypes:- Ingressingress:- from:- podSelector:matchLabels:run: testpodports:- protocol: TCPport: 80

创建一个策略，只允许标签为run=testpod的pod访问

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-network-create]
└─$kubectl  apply  -f networkpolicy-pod.yaml
networkpolicy.networking.k8s.io/test-network-policy created

创建两个pod，都设置--labels=run=testpod标签，只有当前命名空间可以访问

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-network-create]
└─$kubectl  run testpod1 -it --rm --image=yauritux/busybox-curl --image-pull-policy=IfNotPresent --labels=run=testpod --namespace=default/home # curl  --connect-timeout 10 -m 10 svc1.liruilong-network-create
curl: (28) Connection timed out after 10697 milliseconds

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-network-create]
└─$kubectl  run testpod1 -it --rm --image=yauritux/busybox-curl --image-pull-policy=IfNotPresent --labels=run=testpod/home # curl  --connect-timeout 10 -m 10 svc1
pod1
/home #

下面的设置可以其他所有命名空间可以访问

apiVersion: networking.k8s.io/v1
kind: NetworkPolicy
metadata:name: test-network-policynamespace: liruilong-network-create
spec:podSelector:matchLabels:run: pod1policyTypes:- Ingressingress:- from:- podSelector:matchLabels:podSelector:matchLabels:run: testpodports:- protocol: TCPport: 80

default 命名空间和当前命名空间可以访问

apiVersion: networking.k8s.io/v1
kind: NetworkPolicy
metadata:name: test-network-policynamespace: liruilong-network-create
spec:podSelector:matchLabels:run: pod1policyTypes:- Ingressingress:- from:- podSelector:matchLabels:kubernetes.io/metadata.name: defaultpodSelector:matchLabels:run: testpod- podSelector:matchLabels:run: testpod      ports:- protocol: TCPport: 80

定位pod所使用的网络策略

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-network-create]
└─$kubectl  get networkpolicies
NAME                  POD-SELECTOR   AGE
test-network-policy   run=pod1       13m
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-network-create]
└─$kubectl  get pods --show-labels
NAME   READY   STATUS    RESTARTS        AGE     LABELS
pod1   1/1     Running   2 (3d15h ago)   5d12h   run=pod1
pod2   1/1     Running   2 (3d15h ago)   5d12h   run=pod2
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-network-create]
└─$kubectl  get networkpolicies | grep run=pod1
test-network-policy   run=pod1       15m
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-network-create]
└─$

出去策略

apiVersion: networking.k8s.io/v1
kind: NetworkPolicy
metadata:name: test-network-policy
spec:podSelector:matchLabels:run: pod1policyTypes:- Egressegress:- to:- podSelector:matchLabels:run: pod2ports:- protocol: TCPport: 80

pod1只能访问pod2的TCP协议80端口

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-network-create]
└─$kubectl  apply  -f networkpolicy1.yaml

通过IP访问正常pod2

┌──[root@vms81.liruilongs.github.io]-[~]
└─$kubectl  exec -it pod1 -- bash
root@pod1:/# curl 10.111.123.194
pod2

因为DNS的pod在另一个命名空间(kube-system)运行，pod1只能到pod2，所以无法通过域名访问，需要添加另一个命名空间

┌──[root@vms81.liruilongs.github.io]-[~]
└─$kubectl  exec -it pod1 -- bash
root@pod1:/# curl svc2
^C

相关参数获取

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-network-create]
└─$kubectl  get ns --show-labels | grep kube-system
kube-system                  Active   27d     kubernetes.io/metadata.name=kube-system
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-network-create]
└─$kubectl get pods  --show-labels -n kube-system  | grep dns
coredns-7f6cbbb7b8-ncd2s                             1/1     Running   13 (3d19h ago)    24d   k8s-app=kube-dns,pod-template-hash=7f6cbbb7b8
coredns-7f6cbbb7b8-pjnct                             1/1     Running   13 (3d19h ago)    24d   k8s-app=kube-dns,pod-template-hash=7f6cbbb7b8

配置两个出去规则，一个到pod2,一个到kube-dns，使用不同端口协议

apiVersion: networking.k8s.io/v1
kind: NetworkPolicy
metadata:name: test-network-policy
spec:podSelector:matchLabels:run: pod1policyTypes:- Egressegress:- to:- podSelector:matchLabels:run: pod2ports:- protocol: TCPport: 80- to:- namespaceSelector:matchLabels:kubernetes.io/metadata.name: kube-systempodSelector:matchLabels:k8s-app: kube-dnsports:- protocol: UDPport: 53

测试可以通过域名访问

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-network-create]
└─$vim networkpolicy2.yaml
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-network-create]
└─$kubectl  apply  -f networkpolicy2.yaml
networkpolicy.networking.k8s.io/test-network-policy configured
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-network-create]
└─$kubectl  get networkpolicies
NAME                  POD-SELECTOR   AGE
test-network-policy   run=pod1       3h38m
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-network-create]
└─$kubectl  exec -it pod1 -- bash
root@pod1:/# curl svc2
pod2
root@pod1:/#

时间关系，关于网络策略和小伙伴们分享到这里，生活加油