Kubernetes IPVS和IPTABLES

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Kubernetes IPVS和IPTABLES

Kubernetes使用IPVS
- 安装IPVS
- - CentOS
  - Ubuntu

什么是IPVS

IPVS（IP Virtual Server，IP虚拟服务器）实现了传输层的负载平衡，通常称为4 LAN（四层局域网）交换，是Linux内核的一部分。

IPVS在主机上运行，在真实服务器集群前面充当负载平衡器。IPVS可以将基于 TCP 和 UDP 的服务请求定向到真实服务器上。

IPVS vs IPTABLES

IPVS 模式在 Kubernetes v1.8中引入，在v1.9中成为测试版，在v1.11中成为GA。
IPTABLES模式是在v1.1版本中加入的，从v1.2版本开始成为默认的操作模式。

IPVS和IPTABLES都是基于netfilter的。IPVS模式和IPTABLES模式的区别如下：

IPVS为大型集群提供更好的可扩展性和性能。
IPVS比IPTABLES支持更复杂的负载平衡算法（最小负载、最小连接、定位、加权等）。
IPVS 支持服务器健康检查和连接重试等。

IPVS 对 IPTABLES 的依赖

IPVS代理使用IPTABLES做数据包过滤、SNAT或伪装。具体来说，IPVS代理将使用ipset来存储需要DROP或做伪装的流量的源地址或目的地址，以确保无论我们有多少服务，IPTABLES规则的数量不变。

下面是IPVS代理服务器使用的ipset集的表格。

set name	members	usage
KUBE-CLUSTER-IP	All service IP + port	Mark-Masq for cases that `masquerade-all=true` or `clusterCIDR` specified
KUBE-LOOP-BACK	All service IP + port + IP	masquerade for solving hairpin purpose
KUBE-EXTERNAL-IP	service external IP + port	masquerade for packages to external IPs
KUBE-LOAD-BALANCER	load balancer ingress IP + port	masquerade for packages to load balancer type service
KUBE-LOAD-BALANCER-LOCAL	LB ingress IP + port with `externalTrafficPolicy=local`	accept packages to load balancer with `externalTrafficPolicy=local`
KUBE-LOAD-BALANCER-FW	load balancer ingress IP + port with `loadBalancerSourceRanges`	package filter for load balancer with `loadBalancerSourceRanges` specified
KUBE-LOAD-BALANCER-SOURCE-CIDR	load balancer ingress IP + port + source CIDR	package filter for load balancer with `loadBalancerSourceRanges` specified
KUBE-NODE-PORT-TCP	nodeport type service TCP port	masquerade for packets to nodePort(TCP)
KUBE-NODE-PORT-LOCAL-TCP	nodeport type service TCP port with `externalTrafficPolicy=local`	accept packages to nodeport service with `externalTrafficPolicy=local`
KUBE-NODE-PORT-UDP	nodeport type service UDP port	masquerade for packets to nodePort(UDP)
KUBE-NODE-PORT-LOCAL-UDP	nodeport type service UDP port with `externalTrafficPolicy=local`	accept packages to nodeport service with `externalTrafficPolicy=local`

在以下情况下，IPVS 代理将依赖 IPTABLES。

1. kube-proxy以–masquerade-all=true启动

如果kube-proxy以--masquerade-all=true启动，IPVS代理将伪装所有访问服务集群IP的流量，这与IPTABLES代理的行为相同。假设kube-proxy指定了标志--masquerade-all=true，那么IPVS代理安装的IPTABLES应该如下所示：

 # iptables -t nat -nL
 
Chain PREROUTING (policy ACCEPT)
target     prot opt source               destination
KUBE-SERVICES  all  --  0.0.0.0/0            0.0.0.0/0            /* kubernetes service portals */
 
Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination
KUBE-SERVICES  all  --  0.0.0.0/0            0.0.0.0/0            /* kubernetes service portals */
 
Chain POSTROUTING (policy ACCEPT)
target     prot opt source               destination
KUBE-POSTROUTING  all  --  0.0.0.0/0            0.0.0.0/0            /* kubernetes postrouting rules */
 
Chain KUBE-MARK-MASQ (2 references)
target     prot opt source               destination
MARK       all  --  0.0.0.0/0            0.0.0.0/0            MARK or 0x4000
 
Chain KUBE-POSTROUTING (1 references)
target     prot opt source               destination
MASQUERADE  all  --  0.0.0.0/0            0.0.0.0/0            /* kubernetes service traffic requiring SNAT */ mark match 0x4000/0x4000
MASQUERADE  all  --  0.0.0.0/0            0.0.0.0/0            match-set KUBE-LOOP-BACK dst,dst,src
 
Chain KUBE-SERVICES (2 references)
target     prot opt source               destination
KUBE-MARK-MASQ  all  --  0.0.0.0/0            0.0.0.0/0            match-set KUBE-CLUSTER-IP dst,dst
ACCEPT     all  --  0.0.0.0/0            0.0.0.0/0            match-set KUBE-CLUSTER-IP dst,dst

2. 在kube-proxy启动时指定集群CIDR

如果kube-proxy以--cluster-cidr=启动，IPVS代理将伪装访问服务集群IP的非集群流量，其行为与IPTABLES代理相同。假设kube-proxy提供的集群cidr是10.244.16.0/24，那么IPVS代理安装的IPTABLES应该如下所示。

 # iptables -t nat -nL
 
Chain PREROUTING (policy ACCEPT)
target     prot opt source               destination
KUBE-SERVICES  all  --  0.0.0.0/0            0.0.0.0/0            /* kubernetes service portals */
 
Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination
KUBE-SERVICES  all  --  0.0.0.0/0            0.0.0.0/0            /* kubernetes service portals */
 
Chain POSTROUTING (policy ACCEPT)
target     prot opt source               destination
KUBE-POSTROUTING  all  --  0.0.0.0/0            0.0.0.0/0            /* kubernetes postrouting rules */
 
Chain KUBE-MARK-MASQ (3 references)
target     prot opt source               destination
MARK       all  --  0.0.0.0/0            0.0.0.0/0            MARK or 0x4000
 
Chain KUBE-POSTROUTING (1 references)
target     prot opt source               destination
MASQUERADE  all  --  0.0.0.0/0            0.0.0.0/0            /* kubernetes service traffic requiring SNAT */ mark match 0x4000/0x4000
MASQUERADE  all  --  0.0.0.0/0            0.0.0.0/0            match-set KUBE-LOOP-BACK dst,dst,src
 
Chain KUBE-SERVICES (2 references)
target     prot opt source               destination
KUBE-MARK-MASQ  all  -- !10.244.16.0/24       0.0.0.0/0            match-set KUBE-CLUSTER-IP dst,dst
ACCEPT     all  --  0.0.0.0/0            0.0.0.0/0            match-set KUBE-CLUSTER-IP dst,dst

3. loadBalancer类型的服务

对于loadBalancer类型的服务，IPVS代理将安装IPTABLES与ipset KUBE-LOAD-BALANCER匹配。特别是当服务的LoadBalancerSourceRanges被指定或指定externalTrafficPolicy=local时，IPVS代理将创建ipset集KUBE-LOAD-BALANCER-LOCAL/KUBE-LOAD-BALANCER-FW/KUBE-LOAD-BALANCER-SOURCE-CIDR并相应地安装IPTABLES，它应该看起来像下面所示。

 # iptables -t nat -nL
 
Chain PREROUTING (policy ACCEPT)
target     prot opt source               destination
KUBE-SERVICES  all  --  0.0.0.0/0            0.0.0.0/0            /* kubernetes service portals */
 
Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination
KUBE-SERVICES  all  --  0.0.0.0/0            0.0.0.0/0            /* kubernetes service portals */
 
Chain POSTROUTING (policy ACCEPT)
target     prot opt source               destination
KUBE-POSTROUTING  all  --  0.0.0.0/0            0.0.0.0/0            /* kubernetes postrouting rules */
 
Chain KUBE-FIREWALL (1 references)
target     prot opt source               destination
RETURN     all  --  0.0.0.0/0            0.0.0.0/0            match-set KUBE-LOAD-BALANCER-SOURCE-CIDR dst,dst,src
KUBE-MARK-DROP  all  --  0.0.0.0/0            0.0.0.0/0
 
Chain KUBE-LOAD-BALANCER (1 references)
target     prot opt source               destination
KUBE-FIREWALL  all  --  0.0.0.0/0            0.0.0.0/0            match-set KUBE-LOAD-BALANCER-FW dst,dst
RETURN     all  --  0.0.0.0/0            0.0.0.0/0            match-set KUBE-LOAD-BALANCER-LOCAL dst,dst
KUBE-MARK-MASQ  all  --  0.0.0.0/0            0.0.0.0/0
 
Chain KUBE-MARK-DROP (1 references)
target     prot opt source               destination
MARK       all  --  0.0.0.0/0            0.0.0.0/0            MARK or 0x8000
 
Chain KUBE-MARK-MASQ (2 references)
target     prot opt source               destination
MARK       all  --  0.0.0.0/0            0.0.0.0/0            MARK or 0x4000
 
Chain KUBE-POSTROUTING (1 references)
target     prot opt source               destination
MASQUERADE  all  --  0.0.0.0/0            0.0.0.0/0            /* kubernetes service traffic requiring SNAT */ mark match 0x4000/0x4000
MASQUERADE  all  --  0.0.0.0/0            0.0.0.0/0            match-set KUBE-LOOP-BACK dst,dst,src
 
Chain KUBE-SERVICES (2 references)
target     prot opt source               destination
KUBE-LOAD-BALANCER  all  --  0.0.0.0/0            0.0.0.0/0            match-set KUBE-LOAD-BALANCER dst,dst
ACCEPT     all  --  0.0.0.0/0            0.0.0.0/0            match-set KUBE-LOAD-BALANCER dst,dst

4. NodePort类型的服务

对于NodePort类型的服务，IPVS代理将安装IPTABLES与ipset KUBE-NODE-PORT-TCP/KUBE-NODE-PORT-UDP的匹配。当指定externalTrafficPolicy=local时，IPVS代理将创建ipset集KUBE-NODE-PORT-LOCAL-TCP/KUBE-NODE-PORT-LOCAL-UDP并相应地安装IPTABLES，这应该是如下所示的：

假设服务的TCP类型为nodePort。

 Chain PREROUTING (policy ACCEPT)
target     prot opt source               destination
KUBE-SERVICES  all  --  0.0.0.0/0            0.0.0.0/0            /* kubernetes service portals */
 
Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination
KUBE-SERVICES  all  --  0.0.0.0/0            0.0.0.0/0            /* kubernetes service portals */
 
Chain POSTROUTING (policy ACCEPT)
target     prot opt source               destination
KUBE-POSTROUTING  all  --  0.0.0.0/0            0.0.0.0/0            /* kubernetes postrouting rules */
 
Chain KUBE-MARK-MASQ (2 references)
target     prot opt source               destination
MARK       all  --  0.0.0.0/0            0.0.0.0/0            MARK or 0x4000
 
Chain KUBE-NODE-PORT (1 references)
target     prot opt source               destination
RETURN     all  --  0.0.0.0/0            0.0.0.0/0            match-set KUBE-NODE-PORT-LOCAL-TCP dst
KUBE-MARK-MASQ  all  --  0.0.0.0/0            0.0.0.0/0
 
Chain KUBE-POSTROUTING (1 references)
target     prot opt source               destination
MASQUERADE  all  --  0.0.0.0/0            0.0.0.0/0            /* kubernetes service traffic requiring SNAT */ mark match 0x4000/0x4000
MASQUERADE  all  --  0.0.0.0/0            0.0.0.0/0            match-set KUBE-LOOP-BACK dst,dst,src
 
Chain KUBE-SERVICES (2 references)
target     prot opt source               destination
KUBE-NODE-PORT  all  --  0.0.0.0/0            0.0.0.0/0            match-set KUBE-NODE-PORT-TCP dst

5. 指定externalIP的服务

对于指定了外部IP的服务，IPVS代理将安装IPTABLES与ipset KUBE-EXTERNAL-IP匹配，假设我们有指定了外部IP的服务，IPTABLES规则应该如下所示：

 Chain PREROUTING (policy ACCEPT)
target     prot opt source               destination
KUBE-SERVICES  all  --  0.0.0.0/0            0.0.0.0/0            /* kubernetes service portals */
 
Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination
KUBE-SERVICES  all  --  0.0.0.0/0            0.0.0.0/0            /* kubernetes service portals */
 
Chain POSTROUTING (policy ACCEPT)
target     prot opt source               destination
KUBE-POSTROUTING  all  --  0.0.0.0/0            0.0.0.0/0            /* kubernetes postrouting rules */
 
Chain KUBE-MARK-MASQ (2 references)
target     prot opt source               destination
MARK       all  --  0.0.0.0/0            0.0.0.0/0            MARK or 0x4000
 
Chain KUBE-POSTROUTING (1 references)
target     prot opt source               destination
MASQUERADE  all  --  0.0.0.0/0            0.0.0.0/0            /* kubernetes service traffic requiring SNAT */ mark match 0x4000/0x4000
MASQUERADE  all  --  0.0.0.0/0            0.0.0.0/0            match-set KUBE-LOOP-BACK dst,dst,src
 
Chain KUBE-SERVICES (2 references)
target     prot opt source               destination
KUBE-MARK-MASQ  all  --  0.0.0.0/0            0.0.0.0/0            match-set KUBE-EXTERNAL-IP dst,dst
ACCEPT     all  --  0.0.0.0/0            0.0.0.0/0            match-set KUBE-EXTERNAL-IP dst,dst PHYSDEV match ! --physdev-is-in ADDRTYPE match src-type !LOCAL
ACCEPT     all  --  0.0.0.0/0            0.0.0.0/0            match-set KUBE-EXTERNAL-IP dst,dst ADDRTYPE match dst-type LOCAL

Kubernetes使用IPVS

安装IPVS

CentOS

 yum install ipset ipvsadm -y

Ubuntu

 apt-get install ipset ipvsadm -y

设置

 cat > /etc/sysconfig/modules/ipvs.modules <<EOF
#!/bin/bash
modprobe -- ip_vs
modprobe -- ip_vs_rr
modprobe -- ip_vs_wrr
modprobe -- ip_vs_sh
modprobe -- nf_conntrack_ipv4
EOF
chmod 755 /etc/sysconfig/modules/ipvs.modules && bash /etc/sysconfig/modules/ipvs.modules && lsmod | grep -e ip_vs -e nf_conntrack_ipv4

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原文地址：https://www.cnblogs.com/nianshu/p/16905100.html

	# iptables -t nat -nL

	Chain PREROUTING (policy ACCEPT)
	target prot opt source destination
	KUBE-SERVICES all -- 0.0.0.0/0 0.0.0.0/0 /* kubernetes service portals */

	Chain OUTPUT (policy ACCEPT)
	target prot opt source destination
	KUBE-SERVICES all -- 0.0.0.0/0 0.0.0.0/0 /* kubernetes service portals */

	Chain POSTROUTING (policy ACCEPT)
	target prot opt source destination
	KUBE-POSTROUTING all -- 0.0.0.0/0 0.0.0.0/0 /* kubernetes postrouting rules */

	Chain KUBE-MARK-MASQ (2 references)
	target prot opt source destination
	MARK all -- 0.0.0.0/0 0.0.0.0/0 MARK or 0x4000

	Chain KUBE-POSTROUTING (1 references)
	target prot opt source destination
	MASQUERADE all -- 0.0.0.0/0 0.0.0.0/0 /* kubernetes service traffic requiring SNAT */ mark match 0x4000/0x4000
	MASQUERADE all -- 0.0.0.0/0 0.0.0.0/0 match-set KUBE-LOOP-BACK dst,dst,src

	Chain KUBE-SERVICES (2 references)
	target prot opt source destination
	KUBE-MARK-MASQ all -- 0.0.0.0/0 0.0.0.0/0 match-set KUBE-CLUSTER-IP dst,dst
	ACCEPT all -- 0.0.0.0/0 0.0.0.0/0 match-set KUBE-CLUSTER-IP dst,dst

	cat > /etc/sysconfig/modules/ipvs.modules <<EOF
	#!/bin/bash
	modprobe -- ip_vs
	modprobe -- ip_vs_rr
	modprobe -- ip_vs_wrr
	modprobe -- ip_vs_sh
	modprobe -- nf_conntrack_ipv4
	EOF
	chmod 755 /etc/sysconfig/modules/ipvs.modules && bash /etc/sysconfig/modules/ipvs.modules && lsmod \| grep -e ip_vs -e nf_conntrack_ipv4