LVS/NAT原理和特点 ：https://blog.csdn.net/qq_35887546/article/details/104425264
1.实验准备
本次实验需要三个虚拟机以及物理机：
| 虚拟机名称 | 作用 | IP |
|---|---|---|
| server1 | DS | 172.25.63.1（内网） ，172.25.254.100（外网） |
| server2 | RS1 | 172.25.63.2 |
| server3 | RS2 | 172.25.63.3 |
VIP为：172.25.254.100
测试服务：Http 端口：80
物理机为客户端
server2与server3安装apache，在默认发布目录/var/www/html下编写发布文件
2.配置DS
server1 配置好lvsadm
首先删除之前TUN模式添加的策略，及DR模式时添加的隧道：
[root@server1 ~]# ipvsadm -C
[root@server1 ~]# ipvsadm -l
IP Virtual Server version 1.2.1 (size=4096)
Prot LocalAddress:Port Scheduler Flags
-> RemoteAddress:Port Forward Weight ActiveConn InActConn
将之前实验的 ldirectord 和 keepalived 服务停止：
[root@server1 ~]# systemctl stop keepalived
[root@server1 ~]# systemctl stop ldirectord
删除之前设置的VIP和隧道接口：
[root@server1 ~]# modprobe -r ipip
[root@server1 ~]# ip addr del 172.25.63.100/32 dev eth0
[root@server1 ~]# ip addr show
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN qlen 1
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
valid_lft forever preferred_lft forever
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
link/ether 52:54:00:1b:f6:56 brd ff:ff:ff:ff:ff:ff
inet 172.25.63.1/24 brd 172.25.63.255 scope global eth0
valid_lft forever preferred_lft forever
inet6 fe80::5054:ff:fe1b:f656/64 scope link
valid_lft forever preferred_lft forever
2.为DS添加网卡
添加网卡，给新网卡添加外网ip：172.25.254.100，并激活网卡
设置ip：
[root@server1 ~]# ip addr add 172.25.63.100/24 dev eth1
[root@server1 ~]# ip addr show
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN qlen 1
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
valid_lft forever preferred_lft forever
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
link/ether 52:54:00:1b:f6:56 brd ff:ff:ff:ff:ff:ff
inet 172.25.63.1/24 brd 172.25.63.255 scope global eth0
valid_lft forever preferred_lft forever
inet6 fe80::5054:ff:fe1b:f656/64 scope link
valid_lft forever preferred_lft forever
4: eth1: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN qlen 1000
link/ether 52:54:00:5a:47:c7 brd ff:ff:ff:ff:ff:ff
inet 172.25.63.100/24 scope global eth1
valid_lft forever preferred_lft forever
激活网卡：
[root@server1 ~]# ip link set up eth1
[root@server1 ~]# ip addr show
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN qlen 1
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
valid_lft forever preferred_lft forever
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
link/ether 52:54:00:1b:f6:56 brd ff:ff:ff:ff:ff:ff
inet 172.25.63.1/24 brd 172.25.63.255 scope global eth0
valid_lft forever preferred_lft forever
inet6 fe80::5054:ff:fe1b:f656/64 scope link
valid_lft forever preferred_lft forever
4: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
link/ether 52:54:00:5a:47:c7 brd ff:ff:ff:ff:ff:ff
inet 172.25.63.100/24 scope global eth1
valid_lft forever preferred_lft forever
inet6 fe80::5054:ff:fe5a:47c7/64 scope link
valid_lft forever preferred_lft forever
3.为DS添加NAT模式策略
在server1：
NAT模式为-m
[root@server1 ~]# ipvsadm -A -t 172.25.254.100:80 -s rr
[root@server1 ~]# ipvsadm -a -t 172.25.254.100:80 -r 172.25.63.2 -m
[root@server1 ~]# ipvsadm -a -t 172.25.254.100:80 -r 172.25.63.3 -m
[root@server1 ~]# ipvsadm -l
IP Virtual Server version 1.2.1 (size=4096)
Prot LocalAddress:Port Scheduler Flags
-> RemoteAddress:Port Forward Weight ActiveConn InActConn
TCP server1:http rr
-> server2:http Masq 1 0 0
-> server3:http Masq 1 0 0
4.为DS开启路由机制
在server1：
永久开启：
[root@server1 ~]# vim /etc/sysctl.conf
填入：
net.ipv4.ip_forward = 1
[root@server1 ~]# sysctl -p #使更改生效
net.ipv4.ip_forward = 1
临时开启：
sysctl -a | grep ip_forward
sysctl -w net.ipv4.ip_forward=1
sysctl -p
5.为DS加载nat模块
在server1：
[root@server1 ~]# modprobe iptable_nat
注:如果不加载此模块,也可以在第一次访问时成功,但是会在再次访问时出现延迟过长,或访问超时现象
6.配置RS
在server2与server3：
先删除server2 与server3 中的tun 模块（以server 2为例，server3 也是同样的操作）：
[root@server2 ~]# modprobe -r ipip
[root@server2 ~]# ip addr show
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN qlen 1
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
valid_lft forever preferred_lft forever
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
link/ether 52:54:00:fb:99:44 brd ff:ff:ff:ff:ff:ff
inet 172.25.63.2/24 brd 172.25.63.255 scope global eth0
valid_lft forever preferred_lft forever
inet6 fe80::5054:ff:fefb:9944/64 scope link
valid_lft forever preferred_lft forever
给网卡添加网关172.25.63.1（以server 2为例，server3 也是同样的操作）：
永久添加:
[root@server2 ~]# vim /etc/sysconfig/network-scripts/ifcfg-eth0
[root@server2 ~]# cat /etc/sysconfig/network-scripts/ifcfg-eth0
BOOTPROTO=static
DEVICE=eth0
ONBOOT=yes
IPADDR=172.25.63.2
PREFIX=24
GATEWAY=172.25.63.1
[root@server2 ~]# systemctl restart network #重启网络
[root@server2 ~]# route -n
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
0.0.0.0 172.25.63.1 0.0.0.0 UG 0 0 0 eth0 #表示添加成功
169.254.0.0 0.0.0.0 255.255.0.0 U 1002 0 0 eth0
172.25.63.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0
临时添加
route add default gw 172.25.63.1 #删除网关：route del default gw 172.25.8.1
7.测试
在客户端：
[root@foundation63 ~]# curl 172.25.254.100
server3
[root@foundation63 ~]# curl 172.25.254.100
server2
[root@foundation63 ~]# curl 172.25.254.100
server3
[root@foundation63 ~]# curl 172.25.254.100
server2
[root@foundation63 ~]# curl 172.25.254.100
server3
表示nat模式实现成功
