Centos单网卡双网关配置

在网关做端口映射的时候遇到这种问题。网关192.168.0.1映射端口22给192.168.0.100时可以，但是同时192.168.0.2映射端口给192.168.0.100就不行，是应为Centos数据包默认走默认网关，而不是原路返回。
网络结构如下：

网卡eth0 IP 192.168.0.100/24 默认网关 192.168.0.1
网卡eth0:0 IP 192.168.0.101/24 专属网关 192.168.0.2

vim /etc/sysconfig/network-scripts/ifcfg-eth0

TYPE=Ethernet
BOOTPROTO=none
DEVICE=eth0
ONBOOT=yes
IPADDR=192.168.0.100
PREFIX=24
GATEWAY=192.168.0.1
DNS1=192.168.0.1
DNS2=192.168.0.2

vim /etc/sysconfig/network-scripts/ifcfg-eth0:0

TYPE=Ethernet
BOOTPROTO=none
DEVICE=eth0:0
ONBOOT=yes
IPADDR=192.168.0.101
PREFIX=24

加一个备用路由表252 backup
vim /etc/iproute2/rt_tables

#
# reserved values
#
255     local
254     main
253     default
0       unspec
#
# local
#
#1      inr.ruhep
252     backup

路由表规则

ip route flush table backup
ip route add default via 192.168.0.2 dev eth0:0 src 192.168.0.101 table backup
ip rule add from 192.168.0.101 table backup

路由表规则静态化【Centos6】
方法1:
写到/etc/rc.local

vim /etc/rc.local
ip route flush table backup
ip route add default via 192.168.0.2 dev eth0:0 src 192.168.0.101 table backup
ip rule add from 192.168.0.101 table backup

方法2(建议):
写到/etc/sysconfig/network-scripts/route-interface和rule-interface

vim /etc/sysconfig/network-scripts/route-eth0:0
default via 192.168.0.2 dev eth0:0 src 192.168.0.101 table backup
vim /etc/sysconfig/network-scripts/rule-eth0:0
from 192.168.0.101 table backup

路由表规则静态化【Centos8】

nmcli connection modify eth0:0 +ipv4.routes "0.0.0.0/0 192.168.0.2 src=192.168.0.101 table=252"
nmcli connection modify eth0:0 +ipv4.routing-rules "priority 32765 from 192.168.0.101 table 252"