BGP Authentication

A router authenticates the source of each routing update packet that it receives. Many routing protocols support authentication like OSPF, EIGRP, ISIS, BGP, and RIPv2.

Border gateway protocol (BGP) support authentication mechanism using message digest 5 (MD5) algorithms. When authentication I enabled, any TCP segment belonging to BGP exchange between the peers is verified and accepted only if authentication is successful. If the authentication fails, the BGP neighbor relationship goes down (not be established).

Before we start  BGP configuration check out some important  of BGP CCIE exam topics.

Here is the lists of all BGP labs and theories CCNA to CCIE 

1.Introduction of BGP

2.BGP Neighbors

3.BGP Peer Group

4.BGP Attributes

5.BGP Weight Attribute

6.BGP Local Preference (Local_Pref)

7.BGP Multi Exit Discriminator (MED)

8.BGP AS Path Prepending

9.BGP Route Reflectors (RR)

10.BGP Communities_No-advertise configuration

11.BGP community Local-AS

12.BGP Confederations and configuration

13.BGP Route filtering methods

lets see the configuration:-

Topology :

Goal:

• configure the topology as per the diagram 
• configure basic iBGP 
• configure MD5 authentication use password internetworks

R1#show ip interface brief

Interface                   IP-Address      OK? Method Status                Protocol

FastEthernet0/0        10.1.1.1        YES manual up                    up

FastEthernet1/0        unassigned      YES unset  administratively down down

GigabitEthernet2/0  unassigned      YES unset  administratively down down

Serial3/0                     1.1.1.1         YES manual up                    up

R2#show ip interface brief

Interface                  IP-Address      OK? Method Status                Protocol

FastEthernet0/0        20.1.1.1        YES manual up                         up

FastEthernet1/0        unassigned      YES unset  administratively down down

GigabitEthernet2/0    unassigned      YES unset  administratively down down

Serial3/0                      1.1.1.2         YES manual up                      up

R1(config)#router bgp 65011

R1(config-router)#neighbor 1.1.1.2 remote-as 65011

R1(config-router)#network 10.0.0.0

R1(config-router)#network 1.0.0.0

R1(config-router)#no synchronization

R1(config-router)#exit

R2(config)#router  bgp 65011

R2(config-router)#neighbor 1.1.1.1 remote-as 65011

*Mar 22 13:44:19.255: %BGP-5-ADJCHANGE: neighbor 1.1.1.1 Up

R2(config-router)#network 1.0.0.0

R2(config-router)#network 10.0.0.0

R2(config-router)#no synchronization

R2(config-router)#exit

R1# show ip bgp

BGP table version is 3, local router ID is 10.1.1.1

Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,

              r RIB-failure, S Stale, m multipath, b backup-path, f RT-Filter,

              x best-external, a additional-path, c RIB-compressed,

Origin codes: i - IGP, e - EGP, ? - incomplete

RPKI validation codes: V valid, I invalid, N Not found

     Network          Next Hop            Metric LocPrf Weight Path

 * i 1.0.0.0          1.1.1.2                  0    100      0 i

 *>                   0.0.0.0                  0         32768 i

 *>  10.0.0.0         0.0.0.0                  0         32768 i

R1#show ip bgp summary

BGP router identifier 10.1.1.1, local AS number 65011

BGP table version is 3, main routing table version 3

2 network entries using 288 bytes of memory

3 path entries using 240 bytes of memory

2/1 BGP path/bestpath attribute entries using 272 bytes of memory

0 BGP route-map cache entries using 0 bytes of memory

0 BGP filter-list cache entries using 0 bytes of memory

BGP using 800 total bytes of memory

BGP activity 2/0 prefixes, 3/0 paths, scan interval 60 secs

Neighbor        V           AS MsgRcvd MsgSent   TblVer  InQ OutQ Up/Down  State/PfxRcd

1.1.1.2         4        65011      10      10        3    0    0 00:04:49        1

R2#show ip bgp

BGP table version is 4, local router ID is 20.1.1.1

Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,

              r RIB-failure, S Stale, m multipath, b backup-path, f RT-Filter,

              x best-external, a additional-path, c RIB-compressed,

Origin codes: i - IGP, e - EGP, ? - incomplete

RPKI validation codes: V valid, I invalid, N Not found

     Network          Next Hop            Metric LocPrf Weight Path

 *>  1.0.0.0          0.0.0.0                  0         32768 i

 * i                  1.1.1.1                  0    100      0 i

 *>i 10.0.0.0         1.1.1.1                  0    100      0 i

R2#show ip bgp summary

BGP router identifier 20.1.1.1, local AS number 65011

BGP table version is 4, main routing table version 4

2 network entries using 288 bytes of memory

3 path entries using 240 bytes of memory

2/2 BGP path/bestpath attribute entries using 272 bytes of memory

0 BGP route-map cache entries using 0 bytes of memory

0 BGP filter-list cache entries using 0 bytes of memory

BGP using 800 total bytes of memory

BGP activity 2/0 prefixes, 3/0 paths, scan interval 60 secs

Neighbor        V           AS MsgRcvd MsgSent   TblVer  InQ OutQ Up/Down  State/PfxRcd

1.1.1.1         4        65011      11      10        4    0    0 00:05:18        2

R1(config)#router bgp 65011

R1(config-router)#neighbor 1.1.1.2 password internetworks

R1(config-router)#neighbor 1.1.1.2 version 4

R1(config-router)#end

R1#

*Mar 22 13:54:42.691: %TCP-6-BADAUTH: No MD5 digest from 1.1.1.2(179) to 1.1.1.1(47927) tableid - 0

*Mar 22 13:54:42.695: %TCP-6-BADAUTH: No MD5 digest from 1.1.1.2(179) to 1.1.1.1(47927) tableid - 0

*Mar 22 13:54:43.351: %TCP-6-BADAUTH: No MD5 digest from 1.1.1.2(32235) to 1.1.1.1(179) tableid - 0

R2#show ip bgp

BGP table version is 2, local router ID is 20.1.1.1

Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,

              r RIB-failure, S Stale, m multipath, b backup-path, f RT-Filter,

              x best-external, a additional-path, c RIB-compressed,

Origin codes: i - IGP, e - EGP, ? - incomplete

RPKI validation codes: V valid, I invalid, N Not found

     Network          Next Hop            Metric LocPrf Weight Path

 *>  1.0.0.0          0.0.0.0                  0         32768 i

R2#show ip bgp summary

BGP router identifier 20.1.1.1, local AS number 65011

BGP table version is 2, main routing table version 2

1 network entries using 144 bytes of memory

1 path entries using 80 bytes of memory

1/1 BGP path/bestpath attribute entries using 136 bytes of memory

0 BGP route-map cache entries using 0 bytes of memory

0 BGP filter-list cache entries using 0 bytes of memory

BGP using 360 total bytes of memory

BGP activity 3/2 prefixes, 4/3 paths, scan interval 60 secs

Neighbor        V           AS MsgRcvd MsgSent   TblVer  InQ OutQ Up/Down  State/PfxRcd

1.1.1.1           4              65011       0       0        1    0    0 00:02:46                       Active

R2(config)#router bgp 65011

R2(config-router)#neighbor 1.1.1.1 password internetworks

R2(config-router)#neighbor 1.1.1.1 version 4

*Mar 22 13:57:36.931: %BGP-5-ADJCHANGE: neighbor 1.1.1.1 Up

R2(config-router)#end

R2#show ip bgp

BGP table version is 3, local router ID is 20.1.1.1

Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,

              r RIB-failure, S Stale, m multipath, b backup-path, f RT-Filter,

              x best-external, a additional-path, c RIB-compressed,

Origin codes: i - IGP, e - EGP, ? - incomplete

RPKI validation codes: V valid, I invalid, N Not found

     Network          Next Hop            Metric LocPrf Weight Path

 * i 1.0.0.0          1.1.1.1                  0    100      0 i

 *>                   0.0.0.0                  0         32768 i

 *>i 10.0.0.0         1.1.1.1                  0    100      0 i

R2#show ip bgp summary

BGP router identifier 20.1.1.1, local AS number 65011

BGP table version is 3, main routing table version 3

2 network entries using 288 bytes of memory

3 path entries using 240 bytes of memory

2/2 BGP path/bestpath attribute entries using 272 bytes of memory

0 BGP route-map cache entries using 0 bytes of memory

0 BGP filter-list cache entries using 0 bytes of memory

BGP using 800 total bytes of memory

BGP activity 4/2 prefixes, 6/3 paths, scan interval 60 secs

Neighbor        V           AS MsgRcvd MsgSent   TblVer  InQ OutQ Up/Down  State/PfxRcd

1.1.1.1         4        65011       5       5        3    0    0 00:00:44        2

Routing Protocol Authentication (OSPF)

 Routing Protocol Authentication (OSPF)

A router authenticates the source of each routing update packet that it receives. Many routing protocols support authentication like OSPF, EIGRP, ISIS, BGP, and RIPv2.

Cisco routers support of different approaches to authentication route advertisements received from a neighboring router:

•  Simple text authentication
• Hashing authentication (using MD5)

 Simple password authentication:

Router sends packets and key (if a routing protocol doesn’t support multiple keys, the key number associated with a routing update is 0). Neighboring router check whether key matches its key. The outing update is rejected if the keys do not match. The only routing protocols the plan text authentication are RIPv2, OSPF, and ISIS.

MD5 authentication

Configure a key (password) and key ID, router generate a message digest or hash of the key, key ID and message. Message digest is send with packet key is not sent. The neighboring router receives the update and run a hashing algorithm on the routing update with local key, the results in a hash digest. If hash digit matches, the router accept the packet, if it not the update is rejected. This process is more secure than a plain text authentication. IS-IS, OSPF, RIPv2 and EIGRP use MD5.

OSPF Authentication

Types of authentication in OSPF

Type 0 – NULL

Type 1- simple password authentication

Type 2 – cryptographic (SHA/MD5) authentication

OSPF Authentication can be enabled  on OSPF process level (area) or Link level.

All OSPF packet will be authenticated when you enable any formation of authentication in OSPF.

Before we start  BGP configuration check out some important  of BGP CCIE exam topics.

Here are the lists of all OSPF labs and theories CCNA to CCIE.

1.Open Shortest Path First (OSPF) 

2.OSPF Neighbor states

3.OSPF Link State Advertisement (LSA)

4.OSPF STUB, Totally stubby, NSSA, Totally NSSA and(configuration)

5.OSPF Virtual Link

6.Route Redistribution configuration

7.Routing Protocol Authentdication (RIP, and OSPF)

8.Configuring GRE Tunnel instead of virtual link

9. OSPF Autonomous system network map configuration

Let’s see the configuration:

Topology:-

GOAL:

• Configure the topology as per our diagram
• configure OSPF in area 0 and advertise all the interfaces
• configure router 1 and router 2 to exchange routes after establishing successful authentication by using clear text  

R1#show ip interface brief
Interface              IP-Address      OK? Method Status                Protocol
FastEthernet0/0        10.1.1.1        YES manual up                    up
Serial3/0                   1.1.1.1         YES manual up                    down
Loopback0              11.0.0.1        YES manual up                    up
Loopback1              11.0.1.1        YES manual up                    up
Loopback2              11.0.2.1        YES manual up                    up
Loopback3              11.0.3.1        YES manual up                    up

R2#show ip interface brief
Interface              IP-Address      OK? Method Status                Protocol
FastEthernet0/0        20.1.1.1        YES manual up                    up
Serial3/0                   1.1.1.2         YES manual up                    up
Loopback0              12.0.0.1        YES manual up                    up
Loopback1              12.0.1.1        YES manual up                    up
Loopback2              12.0.2.1        YES manual up                    up
Loopback3              12.0.3.1        YES manual up                    up

R1(config)#router ospf 10
R1(config-router)#router-id 11.11.11.11
R1(config-router)#network 1.0.0.0 0.255.255.255 area 0
R1(config-router)#network 10.0.0.0 0.255.255.255 area 0
R1(config-router)#network 11.0.0.0 0.0.0.255 area 0

R2(config)#router ospf 10
R2(config-router)#router-id 12.12.12.12
R2(config-router)#network 12.0.0.0 0.0.0.255 area 0
R2(config-router)#network 20.0.0.0 0.255.255.255 area 0

R2(config-router)#network 1.0.0.0 0.255.255.255 area 0

R1(config)#interface serial 3/0

R1(config-if)#ip ospf authentication

R1(config-if)#ip ospf authentication-key internet

*Dec  5 12:09:31.047: %OSPF-5-ADJCHG: Process 10, Nbr 12.12.12.12 on Serial3/0 from FULL to DOWN, Neighbor Down: Dead timer expired

R2(config)#interface serial 3/0

R2(config-if)#ip ospf authentication

R2(config-if)#ip ospf authentication-key internet

(ip ospf authentication command you can enable plaintext authentication on the

interface level.)

*Dec  5 12:16:37.095: %OSPF-5-ADJCHG: Process 10, Nbr 11.11.11.11 on Serial3/0 from LOADING to FULL, Loading Done

R1#show ip ospf neighbor

Neighbor ID     Pri   State           Dead Time   Address         Interface

12.12.12.12       0   FULL/  -        00:00:39    1.1.1.2         Serial3/0

R2#show ip ospf neighbor

Neighbor ID     Pri   State           Dead Time   Address         Interface

11.11.11.11       0   FULL/  -        00:00:39    1.1.1.1         Serial3/0

(when we have  lots of interfaces do not want to enable OSPF authentication for

each  and every interfaces. we can also enable area-wide authentication by using  area

authentication command). 

lets see:-

R1(config)#router ospf 10

R1(config-router)#area 0 authentication

R1(config-router)#end

*Dec  5 12:27:32.931: OSPF-10 EVENT: Area config: 'area 0 authentication '

R2(config)#router ospf 10

R2(config-router)#area 0 authentication

R1#show ip ospf interface serial 3/0

Serial3/0 is up, line protocol is up

  Internet Address 1.1.1.1/8, Area 0, Attached via Network Statement

  Process ID 10, Router ID 11.11.11.11, Network Type POINT_TO_POINT, Cost: 64

  Topology-MTID    Cost    Disabled    Shutdown      Topology Name

        0           64        no          no            Base

  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 00:00:00

  Supports Link-local Signaling (LLS)

  Cisco NSF helper support enabled

  IETF NSF helper support enabled

  Index 1/1, flood queue length 0

  Next 0x0(0)/0x0(0)

  Last flood scan length is 1, maximum is 1

  Last flood scan time is 0 msec, maximum is 0 msec

  Neighbor Count is 1, Adjacent neighbor count is 1

    Adjacent with neighbor 12.12.12.12

  Suppress hello for 0 neighbor(s)

  Simple password authentication enabled

R2#show ip ospf interface serial 3/0

Serial3/0 is up, line protocol is up

  Internet Address 1.1.1.2/8, Area 0, Attached via Network Statement

  Process ID 10, Router ID 12.12.12.12, Network Type POINT_TO_POINT, Cost: 64

  Topology-MTID    Cost    Disabled    Shutdown      Topology Name

        0           64        no          no            Base

  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 00:00:04

  Supports Link-local Signaling (LLS)

  Cisco NSF helper support enabled

  IETF NSF helper support enabled

  Index 2/2, flood queue length 0

  Next 0x0(0)/0x0(0)

  Last flood scan length is 1, maximum is 1

  Last flood scan time is 0 msec, maximum is 0 msec

  Neighbor Count is 1, Adjacent neighbor count is 1

    Adjacent with neighbor 11.11.11.11

  Suppress hello for 0 neighbor(s)

  Simple password authentication enabled

MD5 in OSPF:-

MD5 authentication we need different commands. First of all we use ip ospf message-digest key

name md5 to specify the key num and the password. name and key number is not matter we can choose whatever name but it must be the same on both sites. To enable OSPF authentication we need

to type  ip ospf authentication message-digest.

 Topology:

 

GOAL:

• we are continuing our previous topology
• erase the simple authentication configuration
• and configure MD5 

R1(config)#router ospf 11

R1(config-router)#router-id 11.11.11.11

R1(config-router)#network 10.0.0.0 0.255.255.255 area 0

R1(config-router)#network 1.0.0.0 0.255.255.255 area 0

R1(config-router)#network 11.0.0.0 0.0.0.255 area 0

R2(config)#router ospf 12

R2(config-router)#router-id 12.12.12.12

R2(config-router)#network 1.0.0.0 0.255.255.255 area 0

R2(config-router)#network 20.0.0.0 0.255.255.255 area 0

R2(config-router)#network 12.0.0.0 0.0.0.255 area 0

R1(config)# router ospf 11

R1(config-router)#  area 0 authentication message-digest

R1(config-router)#  exit

R1(config)#  interface serial 3/0

R1(config-if)#  ip ospf message-digest-key 1 md5 internet

R2(config)# router ospf 11

R2(config-router)#  area 0 authentication message-digest

R2(config-router)#  exit

R2(config)#  interface serial 3/0

R2(config-if)#  ip ospf message-digest-key 1 md5 internet

R1#show ip ospf interface serial 3/0

Serial3/0 is up, line protocol is up

  Internet Address 1.1.1.1/8, Area 0, Attached via Network Statement

  Process ID 11, Router ID 11.11.11.11, Network Type POINT_TO_POINT, Cost: 64

  Topology-MTID    Cost    Disabled    Shutdown      Topology Name

        0           64        no          no            Base

  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

  Supports Link-local Signaling (LLS)

  Cisco NSF helper support enabled

  IETF NSF helper support enabled

  Index 2/2, flood queue length 0

  Next 0x0(0)/0x0(0)

  Last flood scan length is 1, maximum is 1

  Last flood scan time is 0 msec, maximum is 0 msec

  Neighbor Count is 1, Adjacent neighbor count is 1

    Adjacent with neighbor 12.12.12.12

  Suppress hello for 0 neighbor(s)

  Message digest authentication enabled

    Youngest key id is 1

R2#show ip ospf interface serial 3/0

Serial3/0 is up, line protocol is up

  Internet Address 1.1.1.2/8, Area 0, Attached via Network Statement

  Process ID 11, Router ID 12.12.12.12, Network Type POINT_TO_POINT, Cost: 64

  Topology-MTID    Cost    Disabled    Shutdown      Topology Name

        0           64        no          no            Base

  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 00:00:04

  Supports Link-local Signaling (LLS)

  Cisco NSF helper support enabled

  IETF NSF helper support enabled

  Index 2/2, flood queue length 0

  Next 0x0(0)/0x0(0)

  Last flood scan length is 1, maximum is 1

  Last flood scan time is 0 msec, maximum is 4 msec

  Neighbor Count is 1, Adjacent neighbor count is 1

    Adjacent with neighbor 11.11.11.11

  Suppress hello for 0 neighbor(s)

  Message digest authentication enabled

    Youngest key id is 1