OSPF实验5：OSPF认证完整总结
OSPF实验5：OSPF认证完整总结
实验等级：
Expert
实验拓扑：
实验说明：
OSPF
的认证有
2
种类型（确切说是
3
种），其中
type0
表示无认证，
type1
表示明文认证，
type2
表示
MD5
认证。明文认证发送密码进行认证，而
MD5
认证发送的是报文摘要。
有关
MD5
的详细信息，可以参阅
RFC1321.
OSPF
的认证可以在链路上进行，也可以在整个区域内进行认证。另外虚链路同样也可以进行认证。
实验基本配置：
R1:
interface Loopback0
ip address 1.1.1.1 255.255.255.0
!
interface FastEthernet0/0
ip address 21.1.1.1 255.255.255.0
duplex half
!
router ospf 10
router-id 1.1.1.1
log-adjacency-changes
network 10.1.1.0 0.0.0.255 area 0
network 21.1.1.0 0.0.0.255 area 0
R2
：
interface Loopback0
ip address 2.2.2.2 255.255.255.0
!
interface FastEthernet0/0
ip address 21.1.1.2 255.255.255.0
duplex half
!
interface Serial1/0
ip address 10.1.1.2 255.255.255.0
serial restart-delay 0
!
interface Serial1/1
ip address 11.1.1.1 255.255.255.0
serial restart-delay 0
!
router ospf 10
router-id 2.2.2.2
log-adjacency-changes
area 1 virtual-link 3.3.3.3
network 10.1.1.0 0.0.0.255 area 0
network 11.1.1.0 0.0.0.255 area 1
network 21.1.1.0 0.0.0.255 area 0
R3
：
interface Loopback0
ip address 3.3.3.3 255.255.255.0
!
interface Serial1/0
ip address 11.1.1.2 255.255.255.0
serial restart-delay 0
!
router ospf 10
router-id 3.3.3.3
log-adjacency-changes
area 1 virtual-link 2.2.2.2
network 3.3.3.0 0.0.0.255 area 2
network 11.1.1.0 0.0.0.255 area 1
认证配置：
1.
在
R1
和
R2
的串行链路上进行
OSPF
明文认证：
首先先在
R1
上做如下配置，看在
R1
配置完认证，
R2
还没有配置认证的时候的情况：
R1(config)#int s1/0
R1(config-if)#ip ospf authentication
（启用认证）
R1(config-if)#ip ospf authentication-key cisco
（配置密码）
通过
debug
工具我们可以看到如下信息：
*Aug 15 22:51:54.275: OSPF: Rcv pkt from 10.1.1.2, Serial1/0 : Mismatch Authentication type. Input packet specified type 0, we use type 1
这里的
type0
是指对方没有启用认证，
type1
是明文认证。
在
R2
上配置认证，使得邻居关系恢复。
R2(config)#int s1/0
R2(config-if)#ip ospf authentication
R2(config-if)#ip ospf authentication-key cisco
*Aug 15 22:54:55.815: %OSPF-5-ADJCHG: Process 10, Nbr 1.1.1.1 on Serial1/0 from LOADING to FULL, Loading Done
2.
在
R2
和
R3
的串行链路上进行
MD5
认证的：
R2(config)#int s1/1
R2(config-if)#ip ospf authentication message-digest
（定义认证类型为MD5
）
R2(config-if)#ip ospf message-digest-key 1 md5 cisco
（定义key
和密码）
R3(config)#int s1/0
R3(config-if)#ip ospf authentication message-digest
R3(config-if)#ip ospf message-digest-key 1 md5 cisco
R3(config-if)#
*Aug 15 22:59:44.175: %OSPF-5-ADJCHG: Process 10, Nbr 2.2.2.2 on Serial1/0 from LOADING to FULL, Loading Done
R3#show ip ospf int s1/0
Serial1/0 is up, line protocol is up
Internet Address 11.1.1.2/24, Area 1
Process ID 10, Router ID 3.3.3.3, Network Type POINT_TO_POINT, Cost: 64
Transmit Delay is 1 sec, State POINT_TO_POINT,
Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
oob-resync timeout 40
Hello due in 00:00:05
Index 1/1, flood queue length 1
Next 0x648352C8(13)/0x0(0)
Last flood scan length is 1, maximum is 2
Last flood scan time is 0 msec, maximum is 0 msec
Flood pacing timer due in 0 msec
Neighbor Count is 1, Adjacent neighbor count is 1
Adjacent with neighbor 2.2.2.2
Suppress hello for 0 neighbor(s)
Message digest authentication enabled
Youngest key id is 1
3.
修改
R2
和
R3
上串行链路的
MD5
认证的密码：
在
R2
原有的配置上加上下面这条命令：
R2(config-if)#ip ospf message-digest-key 2 md5 gairuhe
R2#sho ip ospf neighbor
Neighbor ID Pri State Dead Time Address Interface
3.3.3.3 0 FULL/ - - 11.1.1.2 OSPF_VL0
1.1.1.1 1 FULL/BDR 00:00:34 21.1.1.1 FastEthernet0/0
1.1.1.1 0 FULL/ - 00:00:37 10.1.1.1 Serial1/0
3.3.3.3 0 FULL/ - 00:00:31 11.1.1.2 Serial1/1
我们发现邻居关系没有丢失。
R2#show ip ospf interface s1/1
Serial1/1 is up, line protocol is up
Internet Address 11.1.1.1/24, Area 1
Process ID 10, Router ID 2.2.2.2, Network Type POINT_TO_POINT, Cost: 64
Transmit Delay is 1 sec, State POINT_TO_POINT,
Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
oob-resync timeout 40
Hello due in 00:00:01
Index 1/3, flood queue length 0
Next 0x0(0)/0x0(0)
Last flood scan length is 1, maximum is 1
Last flood scan time is 4 msec, maximum is 4 msec
Neighbor Count is 1, Adjacent neighbor count is 1
Adjacent with neighbor 3.3.3.3
Suppress hello for 0 neighbor(s)
Message digest authentication enabled
Youngest key id is 2
Rollover in progress, 1 neighbor(s) using the old key(s):
key id 1
这里我们可以看到两个
key
都在使用。
所以要修改链路的
MD5
认证的密码时，可以先将新的密码配置到启用认证的路由器后在将原来的密码删除，这样的话可以保证在修改配置的时候邻居关系依然存在。
4.
在
Area0
上进行区域认证
R1(config)#router ospf 10
R1(config-router)#area 0 authentication
R1(config-router)#
*Aug 15 23:09:32.619: %OSPF-5-ADJCHG: Process 10, Nbr 2.2.2.2 on FastEthernet0/0 from FULL to DOWN, Neighbor Down: Dead timer expired
发现快速以太网接口的邻居已经丢失。通过
debug
信息我们看到：
R1#
*Aug 15 23:10:32.619: OSPF: Rcv pkt from 21.1.1.2, FastEthernet0/0 : Mismatch Authentication type. Input packet specified type 0, we use type 1
我们注意到我们并没有配置密码。也就是说在不配置密码的情况下，仍需要双方都启用认证才可以保持邻居关系。
为了使
R1
和
R2
的快速以太网口恢复邻居关系，我们有两种方法可以使用。
第一种方法是在
R1
的快速以太网口关闭认证
，配置方法如下：
R1(config)#int fa0/0
R1(config-if)#ip ospf authentication null
R1(config-if)#
*Aug 15 23:22:33.227: %OSPF-5-ADJCHG: Process 10, Nbr 2.2.2.2 on FastEthernet0/0 from LOADING to FULL, Loading Done
R1#show ip ospf nei
Neighbor ID Pri State Dead Time Address Interface
2.2.2.2 1 FULL/DR 00:00:39 21.1.1.2 FastEthernet0/0
2.2.2.2 0 FULL/ - 00:00:30 10.1.1.2 Serial1/0
邻居关系已经恢复。
第二种是在
R2
上也开启区域认证
，邻居即可恢复。
R2(config-router)#area 0 authentication
R2(config-router)#
*Aug 15 23:20:43.239: %OSPF-5-ADJCHG: Process 10, Nbr 1.1.1.1 on FastEthernet0/0 from LOADING to FULL, Loading Done
邻居关系也恢复了。
现在我们在
R2
上重启
OSPF
进程。
R2#clear ip ospf pro
Reset ALL OSPF processes? [no]: y
R2#
*Aug 15 23:28:01.275: %OSPF-5-ADJCHG: Process 10, Nbr 3.3.3.3 on OSPF_VL0 from FULL to DOWN, Neighbor Down: Interface down or detached
*Aug 15 23:28:01.279: %OSPF-5-ADJCHG: Process 10, Nbr 1.1.1.1 on FastEthernet0/0 from FULL to DOWN, Neighbor Down: Interface down or detached
*Aug 15 23:28:01.283: %OSPF-5-ADJCHG: Process 10, Nbr 1.1.1.1 on Serial1/0 from FULL to DOWN, Neighbor Down: Interface down or detached
*Aug 15 23:28:01.331: %OSPF-5-ADJCHG: Process 10, Nbr 3.3.3.3 on Serial1/1 from FULL to DOWN, Neighbor Down: Interface down or detached
R2#
*Aug 15 23:28:03.247: %OSPF-5-ADJCHG: Process 10, Nbr 1.1.1.1 on FastEthernet0/0 from LOADING to FULL, Loading Done
R2#
*Aug 15 23:28:05.911: %OSPF-5-ADJCHG: Process 10, Nbr 1.1.1.1 on Serial1/0 from LOADING to FULL, Loading Done
R2#
*Aug 15 23:28:10.423: %OSPF-5-ADJCHG: Process 10, Nbr 3.3.3.3 on Serial1/1 from LOADING to FULL, Loading Done
R2#
等所有的邻居关系起来后，我们到
R1
上看路由表，发现没有
R3
的
loopback
端口。
R1#sho ip rou
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 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 route
Gateway of last resort is not set
1.0.0.0/24 is subnetted, 1 subnets
C 1.1.1.0 is directly connected, Loopback0
21.0.0.0/24 is subnetted, 1 subnets
C 21.1.1.0 is directly connected, FastEthernet0/0
10.0.0.0/24 is subnetted, 1 subnets
C 10.1.1.0 is directly connected, Serial1/0
11.0.0.0/24 is subnetted, 1 subnets
O IA 11.1.1.0 [110/65] via 21.1.1.2, 00:00:57, FastEthernet0/0
因为
R3
是通过虚链路连接到骨干区域的。我们看看
R2
和
R3
之间的虚链路是否正常：
R2#sho ip ospf virtual-links
Virtual Link OSPF_VL0 to router 3.3.3.3 is up
Run as demand circuit
DoNotAge LSA allowed.
Transit area 1, via interface Serial1/1, Cost of using 64
Transmit Delay is 1 sec, State POINT_TO_POINT,
Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
Hello due in 00:00:06
Simple password authentication enabled
R3#sho ip ospf virtual-links
Virtual Link OSPF_VL0 to router 2.2.2.2 is up
Run as demand circuit
DoNotAge LSA allowed.
Transit area 1, via interface Serial1/0, Cost of using 64
Transmit Delay is 1 sec, State POINT_TO_POINT,
Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
Hello due in 00:00:04
因为
virtual-link
属于
Area0
，因此在
R2
配置完成
Area0
区域认证后，
R3
也需要相应的配置。
R3(config)#router ospf 10
R3(config-router)#area 0 authentication
R3(config-router)#
*Aug 15 23:32:57.175: %OSPF-5-ADJCHG: Process 10, Nbr 2.2.2.2 on OSPF_VL0 from LOADING to FULL, Loading Done
R2#sho ip ospf virtual-links
Virtual Link OSPF_VL0 to router 3.3.3.3 is up
Run as demand circuit
DoNotAge LSA allowed.
Transit area 1, via interface Serial1/1, Cost of using 64
Transmit Delay is 1 sec, State POINT_TO_POINT,
Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
Hello due in 00:00:05
Adjacency State FULL (Hello suppressed)
Index 3/4, retransmission queue length 0, number of retransmission 1
First 0x0(0)/0x0(0) Next 0x0(0)/0x0(0)
Last retransmission scan length is 1, maximum is 1
Last retransmission scan time is 0 msec, maximum is 0 msec
Simple password authentication enabled
5.
虚链路的认证配置
虚链路也可以单独配置认证，同样分为
Null
，明文认证，
MD5
认证。
配置命令如下：
Null
：
R2(config-router)#area 1 virtual-link 3.3.3.3 authentication null
R3(config-router)#area 1 virtual-link 2.2.2.2 authentication null
明文：
R2(config-router)#area 1 virtual-link 3.3.3.3 authentication-key cisco
R3(config-router)#area 1 virtual-link 2.2.2.2 authentication-key cisco
MD5
：
R2(config-router)#area 1 virtual-link 3.3.3.3 authentication message-digest
R2(config-router)#area 1 virtual-link 3.3.3.3 message-digest-key 1 md5 cisco
R3(config-router)#area 1 virtual-link 2.2.2.2 authentication message-digest
R3(config-router)#area 1 virtual-link 2.2.2.2 message-digest-key 1 md5 cisco
另外在上个实验我们知道虚链路在建立起来后是
DNA LSA
（不老化
LSA
），所以如果没有重启
OSPF
进程的话，即使一端配置了认证，虚链路也是不会断开的。