# ACL规则优先级 ![image-20240829171502458](https://picgo-noriu.oss-cn-beijing.aliyuncs.com/Images/image-20240829171502458.png) ![image-20240829170059565](https://picgo-noriu.oss-cn-beijing.aliyuncs.com/Images/image-20240829170059565.png) ### 一、IP - AR1 ``` [AR1]int g0/0/0 [AR1-GigabitEthernet0/0/0]ip add 192.168.3.254 24 [AR1-GigabitEthernet0/0/0]int g0/0/1 [AR1-GigabitEthernet0/0/1]ip add 192.168.1.254 24 [AR1-GigabitEthernet0/0/1]int g0/0/2 [AR1-GigabitEthernet0/0/2]ip add 192.168.2.254 24 ``` ### 二、ACL - **AR1** ``` [AR1]acl 2000 [AR1-acl-basic-2000]rule 10 permit source 192.168.1.1 0.0.0.0 [AR1-acl-basic-2000]rule 20 deny source 192.168.1.0 0.0.0.255 [AR1-acl-basic-2000]quit [AR1]int g0/0/0 [AR1-GigabitEthernet0/0/0]traffic-filter outbound acl 2000 ``` ***注释：*** 1. `[AR1]acl 2000`：在设备AR1上创建一个编号为2000的基本ACL。 2. `[AR1-acl-basic-2000]rule 10 permit source 192.168.1.1 0.0.0.0`：在ACL 2000中添加规则10，该规则允许源IP地址为192.168.1.1的数据包通过。 3. `[AR1-acl-basic-2000]rule 20 deny source 192.168.1.0 0.0.0.255`：在ACL 2000中添加规则20，该规则拒绝源IP地址在192.168.1.0/24网段的数据包通过。 4. `[AR1-acl-basic-2000]quit`：退出ACL 2000的配置模式。 5. `[AR1]int g0/0/0`：进入设备AR1的GigabitEthernet0/0/0接口配置模式。 6. `[AR1-GigabitEthernet0/0/0]traffic-filter outbound acl 2000`：在GigabitEthernet0/0/0接口的出方向应用ACL 2000，以过滤出站流量。 > 需要注意的是，ACL规则的执行顺序是从上到下的，因此规则10和规则20的顺序很重要。在这个例子中，由于规则10先于规则20，所以只有源IP地址为192.168.1.1的数据包会被允许通过，而192.168.1.0/24网段的其他数据包将被拒绝。然而，由于规则20覆盖了规则10中的IP地址，实际上所有来自192.168.1.0/24网段的数据包都将被拒绝。这可能是配置错误，通常应该先配置拒绝规则，然后配置允许规则。 ### 三、测试 - **PC间连通性测试** > 全通 - **PC PING Server** - PC1 ``` PC>ping 192.168.3.1 Ping 192.168.3.1: 32 data bytes, Press Ctrl_C to break Request timeout! From 192.168.3.1: bytes=32 seq=2 ttl=254 time=31 ms From 192.168.3.1: bytes=32 seq=3 ttl=254 time=32 ms From 192.168.3.1: bytes=32 seq=4 ttl=254 time=31 ms From 192.168.3.1: bytes=32 seq=5 ttl=254 time=31 ms --- 192.168.3.1 ping statistics --- 5 packet(s) transmitted 4 packet(s) received 20.00% packet loss round-trip min/avg/max = 0/31/32 ms ``` - PC2 ``` PC>ping 192.168.3.1 Ping 192.168.3.1: 32 data bytes, Press Ctrl_C to break Request timeout! Request timeout! Request timeout! Request timeout! Request timeout! --- 192.168.3.1 ping statistics --- 5 packet(s) transmitted 0 packet(s) received 100.00% packet loss ``` - PC3 ``` PC>ping 192.168.3.1 Ping 192.168.3.1: 32 data bytes, Press Ctrl_C to break From 192.168.3.1: bytes=32 seq=1 ttl=254 time=16 ms From 192.168.3.1: bytes=32 seq=2 ttl=254 time=15 ms From 192.168.3.1: bytes=32 seq=3 ttl=254 time=16 ms From 192.168.3.1: bytes=32 seq=4 ttl=254 time<1 ms From 192.168.3.1: bytes=32 seq=5 ttl=254 time=16 ms --- 192.168.3.1 ping statistics --- 5 packet(s) transmitted 5 packet(s) received 0.00% packet loss round-trip min/avg/max = 0/12/16 ms ```