ip rule 路由策略

路由策略（使用ip rule命令操作路由策略数据库）

传统路由：基于数据包目的地址的路由算法。

基于策略的路由比传统路由在功能上更强大，使用更灵活，它使网络管理员不仅能够根据目的地址而且能够根据报文大小，应用或IP源地址等属性来选择转发路径。

ip rule命令：

策略路由组成：

        1）优先级：值越低优先级越高；

        2）策略路由规则：从高优先级匹配数据包，若高优先级的路由规则不适用数据包，则向低优先级的路由规则匹配适用性，直至找到匹配适用的路由规则或匹配全部的路由规则。

        3）路由表：路由表序号和表名的对应关系在 /etc/iproute2/rt_tables文件

1）显示策略路由规则

# ip rule / ip rule list
ip rule
0:      from all lookup local 
1000:   from all lookup rt-static 
10101:  from all to 223.5.5.5 lookup rt-eth2.1 
# 
# 
ip rule list
0:      from all lookup local 
1000:   from all lookup rt-static 
10101:  from all to 223.5.5.5 lookup rt-eth2.1 
# 
# 

2）添加策略路由

# ip rule add
ip rule
0:      from all lookup local 
1000:   from all lookup rt-static 
# 
# from 网络地址或主机地址 to 网络地址或主机地址：数据包的来自和去往
# dev 网卡 ： 来的数据包且是通过br0来的数据包
# table table_name 或 table_num
# pref 优先级
ip rule add from 192.168.0.0/20 to 8.8.8.8 dev br0 table rt-eth2.1 pref 50
# 
ip rule
0:      from all lookup local 
50:     from 192.168.0.0/20 to 8.8.8.8 iif br0 lookup rt-eth2.1 
1000:   from all lookup rt-static 
# 
# 没有指明数据包的来自地址，默认全部from all
ip rule add dev br0 table rt-eth2.1 pref 100
# 
ip rule
0:      from all lookup local 
50:     from 192.168.0.0/20 to 8.8.8.8 iif br0 lookup rt-eth2.1 
100:    from all iif br0 lookup rt-eth2.1 
1000:   from all lookup rt-static 

3）删除符合条件的策略路由

# ip rule del
ip rule
0:      from all lookup local 
50:     from 192.168.0.0/20 to 8.8.8.8 iif br0 lookup rt-eth2.1 
100:    from all iif br0 lookup rt-eth2.1 
1000:   from all lookup rt-static 
# 
# 根据优先级pref删除策略路由
ip rule del pref 50
# 
ip rule
0:      from all lookup local 
100:    from all iif br0 lookup rt-eth2.1 
1000:   from all lookup rt-static
#
# 根据规则删除策略路由 
ip rule del dev br0 table rt-eth2.1
# 
# ip rule
0:      from all lookup local 
1000:   from all lookup rt-static 
# 
# 
ip rule
0:      from all lookup local 
50:     from all iif br0 lookup main 
100:    from all iif br0 lookup rt-eth2.1 
1000:   from all lookup rt-static 
# 
# 注意：根据不完整规则删除策略路由，只能删除优先级最高的那一条
# 一般不建议使用不完整规则删除
# ip rule del dev br0
# 
ip rule
0:      from all lookup local 
100:    from all iif br0 lookup rt-eth2.1 
1000:   from all lookup rt-static 
# 

4）清空全部的策略路由

# ip rule flush 
ip rule
0:	from all lookup local 
1000:	from all lookup rt-static 
10101:	from all to 223.5.5.5 lookup rt-eth2.1 
10201:	from all to 114.114.114.114 lookup rt-eth2.1 
# 
# 注意：本地local路由表建立的策略路由会被保留
ip rule flush
# 
# 
ip rule
0:	from all lookup local 
#