路由器常用ACL和一些简单防护

1、IP欺骗简单防护。如过滤非公有地址访问内部网络。过滤自己内部网络地址；回环地址（127.0.0.0/8）；RFC1918私有地址；DHCP自定义地址  （169.254.0.0/16）；科学文档作者测试用地址（192.0.2.0/24）；不用的组播地址（224.0.0.0/4）；SUN公司的古老的测试地址（20.20.20.0/24；204.152.64.0/23）；全网络地址（0.0.0.0/8）。  Router(Config)# access-list 100 deny ip 127.0.0.0 0.255.255.255 anyRouter(Config)# access-list 100 deny ip 192.168.0.0 0.0.255.255 anyRouter(Config)# access-list 100 deny ip 172.16.0.0 0.15.255.255 anyRouter(Config)# access-list 100 deny ip 10.0.0.0 0.255.255.255 anyRouter(Config)# access-list 100 deny ip 169.254.0.0 0.0.255.255 anyRouter(Config)# access-list 100 deny ip 192.0.2.0 0.0.0.255 anyRouter(Config)# access-list 100 deny ip 224.0.0.0 15.255.255.255 anyRouter(Config)# access-list 100 deny ip 20.20.20.0 0.0.0.255 anyRouter(Config)# access-list 100 deny ip 204.152.64.0 0.0.2.255 anyRouter(Config)# access-list 100 deny ip 0.0.0.0 0.255.255.255 anyRouter(Config)# access-list 100 permit ip any anyRouter(Config-if)# ip access-group 100 in 2、建议采用访问列表控制流出内部网络的地址必须是属于内部网络的。（可选）如： Router(Config)# no access-list 101Router(Config)# access-list 101 permit ip 192.168.0.0 0.0.255.255 anyRouter(Config)# access-list 101 deny ip any anyRouter(Config)# interface eth 0/1Router(Config-if)# description “internet Ethernet”Router(Config-if)# ip address 192.168.0.254 255.255.255.0Router(Config-if)# ip access-group 101 in 其他可选项：建议启用SSH，废弃掉Telnet.但只有支持并带有IPSec特征集的IOS才支持SSH.并且IOS12.0-IOS12.2仅支持SSH-V1.如下配置SSH服务的例子： Router(Config)# no access-list 101Router(Config)# access-list 101 permit ip 192.168.0.0 0.0.255.255 anyRouter(Config)# access-list 101 deny ip any anyRouter(Config)# interface eth 0/1Router(Config-if)# description “internet Ethernet”Router(Config-if)# ip address 192.168.0.254 255.255.255.0Router(Config-if)# ip access-group 101 in Router(Config)# config tRouter(Config)# no access-list 22Router(Config)# access-list 22 permit 192.168.0.22Router(Config)# access-list deny anyRouter(Config)# username test privilege 10 **** ！ 设置SSH的超时间隔和尝试登录次数 Router(Config)# ip ssh timeout 90Router(Config)# ip ssh anthentication-retries 2Router(Config)# line vty 0 4Router(Config-line)# access-class 22 inRouter(Config-line)# transport input sshRouter(Config-line)# login localRouter(Config-line)# exit ！启用SSH服务，生成RSA密钥对。  Router(Config)# crypto key generate rsaThe name for the keys will be: router.xxxChoose the size of the key modulus in the range of 360 to 2048 for your General Purpose Keys .Choosing a key modulus greater than 512 may take a few minutes.How many bits in the modulus[512]: 2048Generating RSA Keys...Router(Config)#