将所有IP地址绑定到服务器上

cd /etc/sysconfig/network-scripts

vim ifcfg-enp2s0
			

# cat ifcfg-enp2s0  
TYPE="Ethernet"
BOOTPROTO="none"
DEFROUTE="yes"
IPV4_FAILURE_FATAL="no"
IPV6INIT="yes"
IPV6_AUTOCONF="yes"
IPV6_DEFROUTE="yes"
IPV6_FAILURE_FATAL="no"
NAME="enp2s0"
UUID="c27c6ef8-ab82-4019-af0a-9f3a70b2d230"
DEVICE="enp2s0"
ONBOOT="yes"
DNS1="8.8.8.8"
IPADDR="192.168.0.1"
...
...
IPADDR247="192.168.0.250"
PREFIX="26"
PERFIX0="24"
GATEWAY="192.168.0.254"
IPV6_PEERDNS="yes"
IPV6_PEERROUTES="yes"
IPV6_PRIVACY="no"
			

IP范围 192.168.0.1-192.168.0.250，接口是enp2s0，enp2s0:1 ~ enp2s0:250

初始化postfix 多实例

postmulti -e init			
			

创建postfix实例

postmulti -I postfix-1 -G mta -e create
...
...
postmulti -I postfix-250 -G mta -e create			
			

启用postfix 实例

postmulti -i postfix-1 -e enable
...
...
postmulti -i postfix-250 -e enable
			

配置postfix实例

postmulti -i postfix-1 -x postconf -e "master_service_disable =" "authorized_submit_users = root" "minimal_backoff_time= 30d" "maximal_backoff_time = 300d" "mynetworks = 127.0.0.0/8,192.168.0.0/24" "inet_interfaces = \$myhostname" "mailbox_size_limit = 0" "message_size_limit = 0" "myhostname =  mail.example.com" "myorigin =  mail.example.com" "mydomain =  example.com" "smtp_bind_address =  192.168.0.1"
...
...
postmulti -i postfix-250 -x postconf -e "master_service_disable =" "authorized_submit_users = root" "minimal_backoff_time= 30d" "maximal_backoff_time = 300d" "mynetworks = 127.0.0.0/8,192.168.0.0/24" "inet_interfaces = \$myhostname" "mailbox_size_limit = 0" "message_size_limit = 0" "myhostname =  mail.example.com" "myorigin =  mail.example.com" "mydomain =  example.com" "smtp_bind_address =  192.168.0.250"
			

iptables -t nat -I POSTROUTING -m state --state NEW -p tcp --dport 25 -o eth0 -m statistic --mode nth --every 250 -j SNAT --to-source 192.168.0.1
...
...
iptables -t nat -I POSTROUTING -m state --state NEW -p tcp --dport 25 -o eth0 -m statistic --mode nth --every 250 -j SNAT --to-source 192.168.0.250
			

注意，不要使用下面的方式配置iptables，经过测试这种192.168.0.1-192.168.0.250方式，不会轮换IP地址。

iptables -t nat -I POSTROUTING -o enp2s0f0 -p tcp -m state --state NEW -m tcp -m statistic --mode nth --every 5 --packet 0 -j SNAT --to-source 192.168.0.1-192.168.0.250