lvs负载均衡的NAT模式

实验前提

server1:172.25.55.1（搭建yum源头，下载好ipvsadm）
server2:172.25.55.2（下载httpd，编辑网页）
server3:172.25.55.3（下载httpd，编辑网页）

打开内核路由功能

[root@server1 ~]# vim /etc/sysctl.conf
net.ipv4.ip_forward = 1
[root@server1 ~]# sysctl -p
net.ipv4.ip_forward = 1
net.ipv4.conf.default.rp_filter = 1
net.ipv4.conf.default.accept_source_route = 0
kernel.sysrq = 0
kernel.core_uses_pid = 1
net.ipv4.tcp_syncookies = 1

添加一块网卡，为网卡配置ip

[root@server1 ~]# ip addr add 172.25.254.100/24 dev eth1
[root@server1 ~]# ip link set up eth1(激活网卡）

[root@server1 ~]# ip addr show
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue state UNKNOWN 
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
    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:d1:f9:32 brd ff:ff:ff:ff:ff:ff
    inet 172.25.55.1/24 brd 172.25.55.255 scope global eth0
    inet6 fe80::5054:ff:fed1:f932/64 scope link 
       valid_lft forever preferred_lft forever
3: eth1: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN qlen 1000
    link/ether 52:54:00:da:7a:e0 brd ff:ff:ff:ff:ff:ff
    inet 172.25.254.100/24 scope global eth1

添加策略

下载ipvsadm

[root@server1 ~]#  ipvsadm -A -t 172.25.254.100:80 -s rr
[root@server1 ~]# ipvsadm -a -t 172.25.254.100:80 -r 172.25.55.2:80 -m
[root@server1 ~]# ipvsadm -a -t 172.25.254.100:80 -r 172.25.55.3:80 -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  172.25.254.100:http rr
  -> server2:http                 Masq    1      0          0         
  -> server3:http                 Masq    1      0          0        
[root@server1 ~]# modprobe iptable_nat

server2和server3的配置:

添加网关
[root@server2 ~]# vim  /etc/sysconfig/network-scripts/ifcfg-eth0 
DEVICE="eth0"
BOOTPROTO="static"
BROADCAST="172.25.55.255"
IPADDR="172.25.55.2"
NETMASK="255.255.255.0"
GATEWAY=172.25.55.1
DNS1=114.114.114
NM_CONTROLLED="yes"
ONBOOT="yes"
[root@server2 ~]# route add default gw 172.25.55.1           
[root@server3 ~]# /etc/init.d/httpd start

测试

[kiosk@foundation55 ~]$ curl 172.25.254.100
HELLO server2
[kiosk@foundation55 ~]$ curl 172.25.254.100
www.westos.com server3