GRE隧道流量的IPSEC加密

1、由于IPSEC只支持对单播流量的加密，所以我们使用GRE隧道可以将广播、组播包封装在一个单播包中，再用IPSEC进行加密。在进行IPSEC配置前应首先配置好GRE隧道，下面是R1上的GRE隧道配置：R1：interface tunnel0 ip address 192.168.3.1 255.255.255.0 tunnel source s1/1 tunnel destination 192.1.1.20 exitinterface s1/1 ip address 192.1.1.40 255.255.255.0 ip access-group perimeter in exitinterf

2、ace lo0 ip address 192.168.1.1 255.255.255.0 exitip route 0.0.0.0 0.0.0.0 192.1.1.20!在这里我将总公司内部的骨干网络设为Area0,隧道部分和分公司内部网络设为Area1router ospf 1 network 192.168.1.0 0.0.0.255 area 0 network 192.168.3.0 0.0.0.255 area 1 exitip access-list extended perimeter permit udp host 192.1.1.20 host 192.1.1.40 eq 5

3、00 permit esp host 192.1.1.20 host 192.1.1.40 permit gre host 192.1.1.20 host 192.1.1.40 deny ip any any exitR2：interface tunnel0 ip address 192.168.3.2 255.255.255.0 tunnel source s1/0 tunnel destination 192.1.1.40 exitinterface s1/0 ip address 192.1.1.20 255.255.255.0 ip access-group perimeter in

4、exitinterface lo0 ip address 192.168.2.1 255.255.255.0 exitip route 0.0.0.0 0.0.0.0 192.1.1.40router ospf 1 network 192.168.2.0 0.0.0.255 area 1 network 192.168.3.0 0.0.0.255 area 1 exitip access-list extended perimeter permit udp host 192.1.1.40 host 192.1.1.20 eq 500 permit esp host 192.1.1.40 hos

5、t 192.1.1.20 permit gre host 192.1.1.40 host 192.1.1.20 deny ip any any exit GRE隧道建立好后，就可以进行IPSEC配置了：R1上的配置：crypto isakmp enablecrypto isakmp identity addresscrypto isakmp policy 10 encryption aes authentication pre-share group 2 hash sha exitcrypto isakmp key cisco123 address 192.1.1.20 no-xauth!IP

6、SEC只对进入GRE隧道的流量进行加密ip access-list extended ToR2 permit gre host 192.1.1.40 host 192.1.1.20 exit!这里的GRE隧道是点对点模式的，所以传输集应使用传输模式crypto ipsec transform-set trans esp-aes esp-sha-hmac mode transport exitcrypto map mymap 10 ipsec-isakmp match address ToR2 set transform-set trans set peer 192.1.1.20 exitint

7、erface s1/1 crypto map mymap exit!最后别忘记删除测试隧道时建立的流量：ip access-list extended perimeter no permit gre host 192.1.1.20 host 192.1.1.40R2上的配置：crypto isakmp enablecrypto isakmp identity addresscrypto isakmp policy 10 encryption aes authentication pre-share group 2 hash sha exitcrypto isakmp key cisco123

8、address 192.1.1.40 no-xauthip access-list extended ToR1 permit gre host 192.1.1.20 host 192.1.1.40 exitcrypto ipsec transform-set trans esp-aes esp-sha-hmac mode transport exitcrypto map mymap 10 ipsec-isakmp match address ToR1 set transform-set trans set peer 192.1.1.40 exitinterface s1/0 crypto ma

9、p mymap exitip access-list extended perimeter no permit gre host 192.1.1.40 host 192.1.1.20测试实验结果：r1#sh ip route Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type

10、2 E1 - OSPF external type 1, E2 - OSPF external type 2 i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2 ia - IS-IS inter area, * - candidate default, U - per-user static route o - ODR, P - periodic downloaded static routeGateway of last resort is 192.1.1.20 to network 0.0.0.0C 1

11、92.1.1.0/24 is directly connected, Serial1/1C 192.168.1.0/24 is directly connected, Loopback0 192.168.2.0/32 is subnetted, 1 subnetsO 192.168.2.1 110/11112 via 192.168.3.2, 00:00:17, Tunnel0C 192.168.3.0/24 is directly connected, Tunnel0S* 0.0.0.0/0 1/0 via 192.1.1.20R1上ping PC2:r1#ping 192.168.2.1Type escape sequence to abort.Sending 5, 100-byte ICMP Echos to 192.168.2.1, timeout is 2 seconds:!Success rate is 100 percent (5/5), round-trip min/avg/max = 36/56/84 msPC1上ping PC2:r1#ping 192.168.2.1 source lo0Type escape sequence to abort.Send