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    • How to configure IPsec tunnel over DMVPN?

    Internetworks October 23, 2021

     In this previous session, we discussed MPLS, DMVPN basic to advance, and IPSec. I am assuming you are familiar with these topics. in this section are going to configure IPsec Over DMVPN.


    1. Introduction of MPLS

    2.What is MPLS Label distributing protocol (LDP) ? How LDP works?

    3.how to configure MPLS LDP Peering ?

    4.What is MPLS L3 VPN ? How to configure?

    5.How to configure MPLS L3 VPN with RIPv2 ?

    6.How to configure MPLS L3 VPN with EIGRP ?

    7.How to configure MPLS L3 VPN with OSPF ?

    8.What is OSPF Sham Links? how to configure OSPF Sham Links?





    let's see the configuration:-

    Topology:-








    R1(config)#interface serial 4/0

    R1(config-if)#ip address 12.1.1.1 255.255.255.0

    R1(config-if)#no shutdown

    R1(config-if)#exit


    R1(config)#interface fastEthernet 0/0

    R1(config-if)#ip address 10.1.1.1 255.255.255.0

    R1(config-if)#no shutdown

    R1(config-if)#exit



    R2(config)#interface serial 4/0
    R2(config-if)#ip address 12.1.1.2 255.255.255.0
    R2(config-if)#no shutdown
    R2(config-if)#exit

    R2(config)#interface serial 4/1
    R2(config-if)#ip address 23.1.1.1 255.255.255.0
    R2(config-if)#no shutdown
    R2(config-if)#exit

    R2(config)#interface fastEthernet 0/0
    R2(config-if)#ip address 20.1.1.1 255.255.255.0
    R2(config-if)#no keepalive
    R2(config-if)#exit

    R2(config)#interface serial 4/2
    R2(config-if)#ip address 24.1.1.1 255.255.255.0
    R2(config-if)#no shutdown
    R2(config-if)#exit

    R2(config)#interface serial 4/1
    R2(config-if)#ip address 23.1.1.1 255.255.255.0
    R2(config-if)#no shutdown

    R3(config)#interface serial 4/1
    R3(config-if)#ip address 23.1.1.2 255.255.255.0
    R3(config-if)#no shutdown
    R3(config-if)#exit

    R3(config)#interface loopback 0
    R3(config-if)#ip address 192.168.30.1 255.255.255.0
    R3(config-if)#exit

    R3(config)#interface fastEthernet 0/0
    R3(config-if)#ip address 30.1.1.1 255.255.255.0
    R3(config-if)#no shutdown
    R3(config-if)#no keepalive
    R3(config-if)#exit


    R4(config)#interface serial 4/2
    R4(config-if)#ip address 24.1.1.2 255.255.255.0
    R4(config-if)#no shutdown
    R4(config-if)#exit

    R4(config)#interface fastEthernet 0/0
    R4(config-if)#ip address 40.1.1.1 255.255.255.0
    R4(config-if)#no shutdown
    R4(config-if)#no keepalive
    R4(config-if)#exit

    R4(config)#interface loopback 0
    R4(config-if)#ip address 192.168.30.1 255.255.255.0
    R4(config-if)#no shutdown
    R4(config-if)#exit


    R1(config)#ip route 0.0.0.0 0.0.0.0 12.1.1.2
    R1(config)#exit

    R2(config)#ip route 192.168.10.0 255.255.255.0 12.1.1.1.
    R2(config)#ip route 10.1.1.0 255.255.255.0 12.1.1.1
    R2(config)#ip route 192.168.30.0 255.255.255.0 23.1.1.2
    R2(config)#ip route 30.1.1.0 255.255.255.0 23.1.1.2
    R2(config)#ip route 40.1.1.0 255.255.255.0 24.1.1.2
    R2(config)#ip route 192.168.40.0 255.255.255.0 24.1.1.2
    R2(config)#ip route 24.1.1.0 255.255.255.0 24.1.1.2
    R2(config)#ip route 23.1.1.0 255.255.255.0 2.1.1.2
    R2(config)#ip route 23.1.1.0 255.255.255.0 23.1.1.2
    R2(config)#ip route 12.1.1.0 255.255.255.0 12.1.1.1
    R2(config)#exit


    R3(config)#ip route 0.0.0.0 0.0.0.0 23.1.1.1
    R3(config)#exit 


    R4(config)#ip route 0.0.0.0 0.0.0.0 24.1.1.1
    R4(config)#exit


    R1(config)#interface tunnel 4321
    R1(config-if)#ip address 192.168.1.1 255.255.255.0
    R1(config-if)#tunnel source 12.1.1.1
    R1(config-if)#tunnel mode gre multipoint

    *Oct 23 15:53:38.431: %LINEPROTO-5-UPDOWN: Line protocol on Interface Tunnel4321, changed state to up

    R1(config-if)#ip nhrp network-id 1
    R1(config-if)#exit

    R3(config)#interface tunnel 4321

    *Oct 23 15:53:52.263: %LINEPROTO-5-UPDOWN: Line protocol on Interface Tunnel4321, changed state to down

    R3(config-if)#ip address 192.168.1.3 255.255.255.0
    R3(config-if)#tunnel source 23.1.1.2
    R3(config-if)#tunnel destination 12.1.1.1

    *Oct 23 15:54:23.315: %LINEPROTO-5-UPDOWN: Line protocol on Interface Tunnel4321, changed state to up

    R3(config-if)#ip nhrp network-id 2
    R3(config-if)#ip nhrp nhs 192.168.1.1
    R3(config-if)#ip nhrp map 192.168.1.1 12.1.1.1
    R3(config-if)#exit


    R4(config)#interface tunnel 4321

    *Oct 23 15:55:05.111: %LINEPROTO-5-UPDOWN: Line protocol on Interface Tunnel4321, changed state to down

    R4(config-if)#ip address 192.168.1.4 255.255.255.0
    R4(config-if)#tunnel source 24.1.1.2
    R4(config-if)#tunnel destination 12.1.1.1

    *Oct 23 15:55:40.667: %LINEPROTO-5-UPDOWN: Line protocol on Interface Tunnel4321, changed state to up

    R4(config-if)#ip nhrp network-id 3
    R4(config-if)#ip nhrp nhs 192.168.1.1
    R4(config-if)#ip nhrp map 192.168.1.1 12.1.1.1
    R4(config-if)#exit


    R1(config)#interface tunnel 4321
    R1(config-if)#ip nhrp map multicast dynamic
    R1(config-if)#exit


    R1(config)#router ospf 1
    R1(config-router)#router-id 1.1.1.1
    R1(config-router)#network 10.0.0.0 255.0.0.0 area 0
    R1(config-router)#network 192.168.1.0 255.0.0.0 area 0
    R1(config-router)#exit

    R3(config)#router ospf 1
    R3(config-router)#router-id 3.3.3.3
    R3(config-router)#network 30.0.0.0 255.0.0.0 area 0
    R3(config-router)#network 192.168.1.0 255.0.0.0 area 0
    R3(config-router)#exit

    R3(config)#interface tunnel 4321
    R3(config-if)#ip ospf network point-to-mult
    R3(config-if)#ip ospf network point-to-multipoint
    R3(config-if)#exit


    R4(config)#router ospf 1
    R4(config-router)#router-id 4.4.4.4
    R4(config-router)#network 40.0.0.0 255.0.0.0 area 0
    R4(config-router)#network 192.168.1.0 255.0.0.0 area 0
    R4(config-router)#exit

    R4(config)#interface tunnel 4321
    R4(config-if)#ip ospf network point-to-mul
    R4(config-if)#ip ospf network point-to-multipoint
    R4(config-if)#exit

    R1(config)#crypto isakmp policy 10
    R1(config-isakmp)#encryption aes
    R1(config-isakmp)#hash sha
    R1(config-isakmp)#authentication pre-share
    R1(config-isakmp)#group 5
    R1(config-isakmp)#exit


    R1(config)#crypto isakmp key 0 mpls123 address 0.0.0.0


    R3(config)#crypto isakmp policy 10
    R3(config-isakmp)#encryption aes
    R3(config-isakmp)#hash sha
    R3(config-isakmp)#authentication pre-share
    R3(config-isakmp)#group 5
    R3(config-isakmp)#exit


    R1(config)#crypto isakmp key 0 mpls123 address 0.0.0.0


    R4(config)#crypto isakmp policy 10
    R4(config-isakmp)#encryption aes
    R4(config-isakmp)#hash sha
    R4(config-isakmp)#authentication pre-share
    R4(config-isakmp)#group 5
    R4(config-isakmp)#exit


    {You can configure more specific IP address of the peers but we are using address 0.0.0.0}


    R1(config)#crypto isakmp key 0 mpls123 address 23.1.1.2
    R1(config)#crypto isakmp key 0 mpls123 address 24.1.1.2

    R3(config)#crypto isakmp key 0 mpls123 address 12.1.1.1
    R3(config)#crypto isakmp key 0 mpls123 address 24.1.1.2


    R4(config)#crypto isakmp key 0 mpls123 address 12.1.1.1
    R4(config)#crypto isakmp key 0 mpls123 address 23.1.1.2



    R1(config)#crypto isakmp key 0 mpls123 address 0.0.0.0


    R1#
    *Oct 23 16:08:14.239: %OSPF-5-ADJCHG: Process 1, Nbr 4.4.4.4 on Tunnel4321 from LOADING to FULL, Loading Done
    R1#
    *Oct 23 16:08:23.587: %OSPF-5-ADJCHG: Process 1, Nbr 3.3.3.3 on Tunnel4321 from LOADING to FULL, Loading Don 


    R1(config)#crypto ipsec transform-set MYSET esp-3des esp-md5-hmac
    R1(cfg-crypto-trans)#exit

    R3(config)#crypto ipsec transform-set MYSET esp-3des esp-md5-hmac
    R3(cfg-crypto-trans)#exit

    R4(config)#crypto ipsec transform-set MYSET esp-3des esp-md5-hmac
    R4(cfg-crypto-trans)#exit



    R1(config)#crypto IPsec profile INTERNETWORKS
    R1(ipsec-profile)#set transform-set MYSET
    R1(ipsec-profile)#exit


    R1(config)#interface tunnel 4321
    R1(config-if)#tunnel protection IPsec profile INTERNETWORKS
    R1(config-if)#EXIT

    *Oct 23 16:12:45.259: %CRYPTO-6-ISAKMP_ON_OFF: ISAKMP is ON



    R3(config)#crypto IPsec profile INTERNETWORKS
    R3(ipsec-profile)#set transform-set MYSET
    R3(ipsec-profile)#exit


    R3(config)#interface tunnel 4321
    R3(config-if)#tunnel protection IPsec profile INTERNETWORKS
    R3(config-if)#EXIT

    *Oct 23 16:12:45.259: %CRYPTO-6-ISAKMP_ON_OFF: ISAKMP is ON



    R4(config)#crypto IPsec profile INTERNETWORKS
    R4(ipsec-profile)#set transform-set MYSET
    R4(ipsec-profile)#exit


    R4(config)#interface tunnel 4321
    R4(config-if)#tunnel protection IPsec profile INTERNETWORKS
    R4(config-if)#EXIT

    *Oct 23 16:12:45.259: %CRYPTO-6-ISAKMP_ON_OFF: ISAKMP is ON


    R1#show crypto session
    Crypto session current status

    Interface: Tunnel4321
    Session status: UP-ACTIVE
    Peer: 24.1.1.2 port 500
      IKEv1 SA: local 12.1.1.1/500 remote 24.1.1.2/500 Active
      IPSEC FLOW: permit 47 host 12.1.1.1 host 24.1.1.2
            Active SAs: 4, origin: crypto map

    Interface: Tunnel4321
    Session status: UP-ACTIVE
    Peer: 23.1.1.2 port 500
      IKEv1 SA: local 12.1.1.1/500 remote 23.1.1.2/500 Active
      IPSEC FLOW: permit 47 host 12.1.1.1 host 23.1.1.2
            Active SAs: 4, origin: crypto map

    R3#show crypto session
    Crypto session current status

    Interface: Tunnel4321
    Session status: UP-ACTIVE
    Peer: 12.1.1.1 port 500
      IKEv1 SA: local 23.1.1.2/500 remote 12.1.1.1/500 Active
      IPSEC FLOW: permit 47 host 23.1.1.2 host 12.1.1.1
            Active SAs: 4, origin: crypto map


    R4#show crypto session
    Crypto session current status

    Interface: Tunnel4321
    Session status: UP-ACTIVE
    Peer: 12.1.1.1 port 500
      IKEv1 SA: local 24.1.1.2/500 remote 12.1.1.1/500 Active
      IPSEC FLOW: permit 47 host 24.1.1.2 host 12.1.1.1
            Active SAs: 4, origin: crypto map


    R1#show dmvpn
    Legend: Attrb --> S - Static, D - Dynamic, I - Incomplete
            N - NATed, L - Local, X - No Socket
            # Ent --> Number of NHRP entries with same NBMA peer
            NHS Status: E --> Expecting Replies, R --> Responding, W --> Waiting
            UpDn Time --> Up or Down Time for a Tunnel
    ==========================================================================

    Interface: Tunnel4321, IPv4 NHRP Details
    Type:Hub, NHRP Peers:2,

     # Ent  Peer NBMA Addr Peer Tunnel Add State  UpDn Tm Attrb
     ----- --------------- --------------- ----- -------- -----
         1 23.1.1.2            192.168.1.3    UP 01:34:52     D
         1 24.1.1.2            192.168.1.4    UP 01:33:09     D


    R3#show dmvpn
    Legend: Attrb --> S - Static, D - Dynamic, I - Incomplete
            N - NATed, L - Local, X - No Socket
            # Ent --> Number of NHRP entries with same NBMA peer
            NHS Status: E --> Expecting Replies, R --> Responding, W --> Waiting
            UpDn Time --> Up or Down Time for a Tunnel
    ==========================================================================

    Interface: Tunnel4321, IPv4 NHRP Details
    Type:Spoke, NHRP Peers:1,

     # Ent  Peer NBMA Addr Peer Tunnel Add State  UpDn Tm Attrb
     ----- --------------- --------------- ----- -------- -----
         1 12.1.1.1            192.168.1.1    UP 00:46:35     S


    R4#show dmvpn
    Legend: Attrb --> S - Static, D - Dynamic, I - Incomplete
            N - NATed, L - Local, X - No Socket
            # Ent --> Number of NHRP entries with same NBMA peer
            NHS Status: E --> Expecting Replies, R --> Responding, W --> Waiting
            UpDn Time --> Up or Down Time for a Tunnel
    ==========================================================================

    Interface: Tunnel4321, IPv4 NHRP Details
    Type:Spoke, NHRP Peers:1,

     # Ent  Peer NBMA Addr Peer Tunnel Add State  UpDn Tm Attrb
     ----- --------------- --------------- ----- -------- -----
         1 12.1.1.1            192.168.1.1    UP 00:46:45     S

    R1#show crypto ipsec transform-set
    Transform set default: { esp-aes esp-sha-hmac  }
       will negotiate = { Transport,  },

    Transform set MYSET: { esp-3des esp-md5-hmac  }
       will negotiate = { Tunnel,  },

    R3#show crypto ipsec transform-set
    Transform set default: { esp-aes esp-sha-hmac  }
       will negotiate = { Transport,  },

    Transform set MYSET: { esp-3des esp-md5-hmac  }
       will negotiate = { Tunnel,  },

    R4#show crypto ipsec transform-set
    Transform set default: { esp-aes esp-sha-hmac  }
       will negotiate = { Transport,  },

    Transform set MYSET: { esp-3des esp-md5-hmac  }
       will negotiate = { Tunnel,  },


    R1#ping 192.168.1.3 source 10.1.1.1
    Type escape sequence to abort.
    Sending 5, 100-byte ICMP Echos to 192.168.1.3, timeout is 2 seconds:
    Packet sent with a source address of 10.1.1.1
    !!!!!
    Success rate is 100 percent (5/5), round-trip min/avg/max = 56/65/88 ms

    R1#ping 192.168.1.4 source 10.1.1.1
    Type escape sequence to abort.
    Sending 5, 100-byte ICMP Echos to 192.168.1.4, timeout is 2 seconds:
    Packet sent with a source address of 10.1.1.1
    !!!!!
    Success rate is 100 percent (5/5), round-trip min/avg/max = 56/69/112 ms

    R4#ping 192.168.1.1 source 40.1.1.1
    Type escape sequence to abort.
    Sending 5, 100-byte ICMP Echos to 192.168.1.1, timeout is 2 seconds:
    Packet sent with a source address of 40.1.1.1
    !!!!!
    Success rate is 100 percent (5/5), round-trip min/avg/max = 56/67/92 ms

    R4#ping 192.168.1.3 source 40.1.1.1
    Type escape sequence to abort.
    Sending 5, 100-byte ICMP Echos to 192.168.1.3, timeout is 2 seconds:
    Packet sent with a source address of 40.1.1.1
    !!!!!
    Success rate is 100 percent (5/5), round-trip min/avg/max = 68/79/84 ms


    R1#show crypto ipsec profile
    IPSEC profile INTERNETWORKS
            Security association lifetime: 4608000 kilobytes/3600 seconds
            Responder-Only (Y/N): N
            PFS (Y/N): N
            Transform sets={
                    MYSET:  { esp-3des esp-md5-hmac  } ,
            }

    IPSEC profile default
            Security association lifetime: 4608000 kilobytes/3600 seconds
            Responder-Only (Y/N): N
            PFS (Y/N): N
            Transform sets={
                    default:  { esp-aes esp-sha-hmac  } ,
            }

    R3#show crypto ipsec profile
    IPSEC profile INTERNETWORKS
            Security association lifetime: 4608000 kilobytes/3600 seconds
            Responder-Only (Y/N): N
            PFS (Y/N): N
            Transform sets={
                    MYSET:  { esp-3des esp-md5-hmac  } ,
            }

    IPSEC profile default
            Security association lifetime: 4608000 kilobytes/3600 seconds
            Responder-Only (Y/N): N
            PFS (Y/N): N
            Transform sets={
                    default:  { esp-aes esp-sha-hmac  } ,
            }



    R4#show crypto IPsec profile
    IPSEC profile INTERNETWORKS
            Security association lifetime: 4608000 kilobytes/3600 seconds
            Responder-Only (Y/N): N
            PFS (Y/N): N
            Transform sets={
                    MYSET:  { esp-3des esp-md5-hmac  } ,
            }

    IPSEC profile default
            Security association lifetime: 4608000 kilobytes/3600 seconds
            Responder-Only (Y/N): N
            PFS (Y/N): N
            Transform sets={
                    default:  { esp-aes esp-sha-hmac  } ,
            }


     


     


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    What is IKE (Internet Key Exchange)? How to configure IPSec site-to-site?

    Internetworks August 21, 2021

    IKE (Internet Key Exchange) Phase 1

    The main reason for IKE phase 1 is to establish a secure for IKE phase 2 or IPsec. let understand Phase 1 in steps 

    • The first step is Negotiation between future neighbors or peers have traffic to be 

    Step 1: Negotiation

    the neighbor (peer) which having traffic and want to protect will initiate the initiate INK phase 1 negotiation. Peers will negotiate about the following:

    • Hashing: peers will use a hashing algorithm to verifying the integrity and use MD5 or SHA.
    • Authentication: peers have to show their identity to prove who he is. Peers use shared keys or digital certificates.
    • DH (Diffie Hellman) group : DH group determines how strong the key is and it's used in the exchange process of the key. The higher number means more secure but it takes longer to compute.
    • Lifetime: lifetime means how long does the IKE phase 1 tunnel stand up? The shorter the lifetime means the more secure it is because rebuilding the tunnel means we will also use new keying material. Each the vendor uses a different lifetime; a default value is 86400 seconds (1 day).
    • Encryption: algorithm we use for encryption DES, 3DES, or AES.


    Step 2: DH Key Exchange

    After completing the negotiation process, now both the peers will know what kind of policy they have to use. Now they will use the DH the group for negotiating and to exchange keying material and in the end result both peers will have a shared key.

    Step 3: Authentication

    in the previous step, both peers authenticate each other using authenticate method in which they agreed on in the negotiation process. Once the authentication is successful it’s mean we that both peers can send and receive on this tunnel (the tunnel is completed).

    The three steps above can be completed using two different modes:

    • Main mode
    • Aggressive mode 


    IKE Phase 2

    IPSec tunnel or IKE phase 2 is used to protect user data. In the IKE phase 2 tunnel, there is only one mode for building the IPSec tunnel is called Quick mode.

    As peers negotiate in IKE phase 1, our IKE phase 2 (IPSec) peers will be negotiated.

    • IPsec Protocol: AH or ESP
    • Encapsulation Mode: transport or tunnel mode.
    • Encryption: what encryption algorithm  DES, 3DES, or AES.
    • Authentication: what authentication algorithm is MD5 or SHA.
    • Lifetime: how long is the IKE phase 2 tunnel valid? When the tunnel is about to expire, we will refresh the keying material.

    (Optional) DH exchange: used for PFS (Perfect Forward Secrecy).

    IPsec Protocols

    AH, and ESP is the two protocols that we use to protect user data. Both of them can be used in transport or tunnel mode, let’s see all the possible options.

    Authentication Header Protocol     

    AH offers authentication and integrity which is good but it doesn’t provide any encryption. AH protects IP packet by calculating a hash value over almost all fields in the IP header. The fields it excludes are the ones that can be changed in transit (TTL and header checksum).

    Transport Mode

    Transport mode is very simple, it just adds an AH header just after the IP header. Here’s an example of an IP packet that carries some TCP traffic:



    Tunnel Mode

    In tunnel mode, we add a new IP header on top of the original IP packet. So this could be useful when you are using private IP addresses and you need to tunnel your traffic over the Internet. Yes we can use AH but it doesn’t provide encryption


    In simple words, IPsec uses three main protocols to create a security framework

    • ESP Encapsulation security payload is used for providing encryption, authentication, and sharing data.
    • AH, Authentication Header use provides a framework for authentication and sharing data.
    • IKE Internet Key Exchange offers a framework for negotiating security parameters and establishing authenticating keys. 







    Let's take a look at our topology: 

    Goal:
    • configure a site-to-site VPN 
    • configure IPSec VPN on router 1 and router 2
    • enable IKE policy on both the routers
    • verify site-to-site IPSec VPN
    • Test IPSec VPN.
    • configure an authentication type pre-shared keys
    • use AES 256 encryption, SHA Hash algorithm, and DH group 3 key exchange 
      • configure lifetime of one hour



      R1(config)#interface serial 4/0

      R1(config-if)#ip address 1.1.1.1 255.0.0.0

      R1(config-if)#no shutdown

      R1(config-if)#interface fastethernet 0/0

      R1(config-if)#ip address 10.1.1.1 255.0.0.0

      R1(config-if)#no shutdown

      R1(config-if)#no keepalive

      R1(config-if)#exit

      R1(config)#interface loopback 0

      R1(config-if)#ip address 192.168.10.1 255.255.255.0

      R1(config-if)#no shutdown

      R1(config-if)#exit


      R2(config-if)#interface serial 4/1

      R2(config-if)#ip address 3.3.3.1 255.0.0.0

      R2(config-if)#no shutdown


      R2(config-if)#interface serial 4/2

      R2(config-if)#ip address 4.4.4.1 255.0.0.0

      R2(config-if)#no shutdown


      R3(config)#interface serial 4/1
      R3(config-if)#ip address 3.3.3.2 255.0.0.0
      R3(config-if)#no shutdown

      R3(config-if)#interface fastethernet 0/0
      R3(config-if)#ip address 30.1.1.1 255.0.0.0
      R3(config-if)#no shutdown
      R3(config-if)#no keepalive
      R3(config-if)#exit
      R1(config)#ip route 0.0.0.0 0.0.0.0 serial 4/0
      R1(config)#exit


      R2(config)#ip route 1.0.0.0 255.0.0.0 serial 4/0
      R2(config)#ip route 10.0.0.0 255.0.0.0 serial 4/0
      R2(config)#ip route 30.0.0.0 255.0.0.0 serial 4/1
      R2(config)#ip route 3.0.0.0 255.0.0.0 serial 4/1
      R2(config)#ip route 4.0.0.0 255.0.0.0 serial 4/2
      R2(config)#ip route 40.0.0.0 255.0.0.0 serial 4/2
      R2(config)#exit


      R3(config)#ip route 0.0.0.0 0.0.0.0 serial 4/1
      R3(config)#exit

      R1#ping 30.1.1.1

      Type escape sequence to abort.

      Sending 5, 100-byte ICMP Echos to 30.1.1.1, timeout is 2 seconds:

      !!!!!

      Success rate is 100 percent (5/5), round-trip min/avg/max = 72/92/156 ms

      R3#ping 10.0.0.0

      Type escape sequence to abort.

      Sending 5, 100-byte ICMP Echos to 10.0.0.0, timeout is 2 seconds:

      !!!!!

      Success rate is 100 percent (5/5), round-trip min/avg/max = 52/56/60 ms

      R1(config)#access-list 100 permit ip 192.168.10.0 0.0.0.255 192.168.20.0 0.0.0.255

      R1(config)#access-list 100 permit ip 192.168.20.0 0.0.0.255 192.168.10.0 0.0.0.255


      R1(config)#crypto isakmp enable

      R2(config)#crypto isakmp enable

      R1(config)#crypto isakmp policy 10

      R1(config-isakmp)#authentication pre-share

      R1(config-isakmp)#encryption aes 256

      R1(config-isakmp)#hash sha

      R1(config-isakmp)# group 3

      R1(config-isakmp)#lifetime 3600

      R1(config-isakmp)#end


      R3(config)#crypto isakmp enable

      R3(config)#crypto isakmp policy 10

      R3(config-isakmp)#authentication pre-share

      R3(config-isakmp)#encryption aes ?

        128  128 bit keys.

        192  192 bit keys.

        256  256 bit keys.

        <cr>

       

      R3(config-isakmp)#encryption aes 256

      R3(config-isakmp)#hash sha?

      sha  sha256  sha384  sha512

       

      R3(config-isakmp)#hash sha

      R3(config-isakmp)#group 3

      R3(config-isakmp)#lifetime 3600


      R3(config-isakmp)#do show crypto isakmp policy

       

      Global IKE policy

      Protection suite of priority 10

              encryption algorithm:   AES - Advanced Encryption Standard (256 bit keys).

              hash algorithm:         Secure Hash Standard

              authentication method:  Pre-Shared Key

              Diffie-Hellman group:   #3 (1536 bit)

              lifetime:               3600 seconds, no volume limit


      R1(config)#crypto isakmp key 0 cisco123 address 2.2.2.2


      R3(config-isakmp)#crypto isakmp key 0 cisco123 address 1.1.1.1

      R1(config)#crypto ipsec transform-set ip_set esp-aes 256 esp-sha-hmac

      R3(config)#crypto ipsec transform-set ip_set esp-aes 256 esp-sha-hmac

      R3(cfg-crypto-trans)#exit

      R1(config)#crypto map CRMAP 10 ipsec-isakmp

      % NOTE: This new crypto map will remain disabled until a peer

              and a valid access list have been configured.

      R1(config-crypto-map)#match address 100

      R1(config-crypto-map)#set peer 2.2.2.2

      R1(config-crypto-map)#set transform-set ip_set

      R1(config-crypto-map)#exit


      R1(config)#interface serial 4/0

      R1(config-if)#crypto map CRMAP

      *Jul 30 14:16:13.923: %CRYPTO-6-ISAKMP_ON_OFF: ISAKMP is ON

      R1(config-if)#END

      R3(config)#crypto map CRMAP 10 ipsec-isakmp

      % NOTE: This new crypto map will remain disabled until a peer

              and a valid access list have been configured.

      R3(config-crypto-map)#match address 100

      R3(config-crypto-map)#set peer 1.1.1.1

      R3(config-crypto-map)#set transform-set ip_set

      R3(config-crypto-map)#end

      R3(config)#interface serial 4/1

      R3(config-if)#crypto map CRMAP


      R1#show crypto ipsec transform-set

      Transform set default: { esp-aes esp-sha-hmac  }

         will negotiate = { Transport,  },

       

      Transform set ip_set: { esp-256-aes esp-sha-hmac  }

         will negotiate = { Tunnel,  },


      R3(config)#do show crypto ipsec transform-set

      Transform set default: { esp-aes esp-sha-hmac  }

         will negotiate = { Transport,  },

       

      Transform set ip_set: { esp-256-aes esp-sha-hmac  }

         will negotiate = { Tunnel,  },

       

      R1#show crypto map

      Crypto Map IPv4 "CRMAP" 10 ipsec-isakmp

              Peer = 2.2.2.2

              Extended IP access list 100

                  access-list 100 permit ip 192.168.10.0 0.0.0.255 192.168.30.0 0.0.0.255

              Current peer: 2.2.2.2

              Security association lifetime: 4608000 kilobytes/3600 seconds

              Responder-Only (Y/N): N

              PFS (Y/N): N

              Transform sets={

                      ip_set:  { esp-256-aes esp-sha-hmac  } ,

              }

              Interfaces using crypto map CRMAP:

                      Serial4/0

       R1#ping 2.2.2.2 source 10.1.1.1

      Type escape sequence to abort.

      Sending 5, 100-byte ICMP Echos to 2.2.2.2, timeout is 2 seconds:

      Packet sent with a source address of 10.1.1.1

      !!!!!

      Success rate is 100 percent (5/5), round-trip min/avg/max = 56/109/208 ms

      R1#ping 192.168.30.1 so

      R1#ping 192.168.30.1 source 1.1.1.1

      Type escape sequence to abort.

      Sending 5, 100-byte ICMP Echos to 192.168.30.1, timeout is 2 seconds:

      Packet sent with a source address of 1.1.1.1

      !!!!!

      Success rate is 100 percent (5/5), round-trip min/avg/max = 52/68/88 ms
      Read More

      What is IPSec (Internet protocol security)? What is Internet Key Exchange IKE? How to configure IPSec tunnel?

      Internetworks July 29, 2021

      (Internet Protocol Security) IPSec is a set of protocols developed by the Internet Engineering Task Force (IETF). Internet protocol security (IPsec)  is a framework that helps us to protect our IP traffic on the network layer. Why? Because the ( internet protocol) IP protocol itself doesn’t have any security features at all. IPsec allows two or more hosts to communicate securely by authenticating and encrypting each IP packet of a communication session.




      IPsec can protect our traffic with the following features:

      • Confidentiality: by encrypting your data, nobody can read it except the sender and the receiver will be able to read your data. This means that the contents are not visible to third parties 
      • Integrity: we want to make sure that no one can make changes to the data in our packets. No one can modify the data (Hashing algorithms) By calculating a hash value, the sender and receiver will be able to check if changes have been made to the packet.
      • Authentication: the sender and receiver will authenticate each other to make sure that we are really talking with the device we intend to.
      • Anti-replay: even if a packet is encrypted and authenticated, an attacker could try to capture these packets and send them again. By using sequence numbers, IPsec will not transmit any duplicate packets. This means ensuring packets are received only once a security service where the receiver can reject old or duplicate packets in order to defeat replay attacks.




      We can use IPSec on many different devices; we can use it on routers, firewalls, hosts, and servers. IPSec is a bit complex and there are a lot of different ways to implement on.

      We need to understand and build the IPSec tunnel before we protect any IP packets. For establishing an IPSec tunnel we have a protocol called Internet Key Exchange (IKE).

      We have two phases for building an IPSec tunnel:

      1. Internet Key Exchange (IKE) phase 1
      2. Internet Key Exchange (IKE) phase 2

      In Internet Key Exchange (IKE)  phase 1, two peers are going to negotiate about the encryption, authentication, hashing values, and other protocol parameters that are required, which means providing a framework for the negotiation of security parameters and  Establishment of authenticated keys.



       In this phase, an Internet Security Association and Key Management Protocol (ISAKMP) session is established. This is also called the ISAKMP tunnel or IKE phase 1 tunnel. all the parameters that the two devices will use are called SA (Security Association). 

      We establish Internet Key Exchange IKE Phase 1 tunnel for traffic management, this tunnel is a method of secure establishing the second tunnel or Phase 2 in other words IPsec tunnel.


      now we have an IPsec tunnel and we can send through the IKE Phase 2 tunnel or IPSec tunnel but IKE doesn't authenticate our data or encrypt our used data so we use other protocols that will help us authenticate and encrypt our data.

      • Authenticate Header (AH)
      • Encapsulating Security Payload (ESP)

      both protocols give us authentication and integrity but ESP is today's protocol because it supports encryption. these two protocols AH and ESP offer two different modes:

      • Transparent mode- in this mode we use the original IP header.
      • Tunnel mode- in this mode we use a new IP header. 


      The five steps of IPSec are as follows:-

      Initiation we need something to start our tunnel. let's take the example of a router when we configure IPSec, the router uses an access list for what data must be protected,ed and when our router gets something that matches our assessment, the router will start the Internet Key Exchange IKE process or we can manually initiate our tunnel.

       Internet Key Exchange IKE phase 1: First we negotiate a security association to build the IKE phase 1 tunnel (ISAKMP tunnel).

       Internet Key Exchange IKEphase 2: second within the IKE phase 1 tunnel, we will build the IKE phase 2 tunnel or IPSec tunnel.

      Data transfer: we use the IKE phase 2 tunnel or IPSec tunnel for sending our user data.

      Termination: The IPSec tunnel will terminate when there is no user data to protect.

      { In the next section we take a closer look at all the components}

       

       

       
      Read More

      How to configure External BGP and EIGRP on DMVPN Phase 2?

      Internetworks May 28, 2021

       

       

      The first DMVPN lesson explained the basics and I explained how to configure a basic DMVPN phase 2 network. I also explain how to configure the EIGRP phase 1 network and OSPF Phase 1 network. 

      In this lesson, we’ll take a look at how we can use external BGP on DMVPN phase 2 networks and EIGRP. Here is the topology we will use:




      R1(config)#interface serial 4/0

      R1(config-if)#ip address 1.1.1.1 255.0.0.0

      R1(config-if)#no shutdown


      R1(config-if)#interface fastethernet 0/0

      R1(config-if)#ip address 10.1.1.1 255.0.0.0

      R1(config-if)#no shutdown

      R1(config-if)#exit



      R2(config)#interface serial 4/0

      R2(config-if)#ip address 1.1.1.2 255.0.0.0

      R2(config-if)#no shutdown


      R2(config-if)#interface serial 4/1

      R2(config-if)#ip address 3.3.3.1 255.0.0.0

      R2(config-if)#no shutdown


      R2(config-if)#interface serial 4/2

      R2(config-if)#ip address 4.4.4.1 255.0.0.0

      R2(config-if)#no shutdown


      R2(config-if)#interface fastethernet 0/0

      R2(config-if)#ip address 20.1.1.1 255.0.0.0

      R2(config-if)#no shutdown

      R2(config-if)#no keepalive

      R2(config-if)#exit



      R3(config)#interface serial 4/1

      R3(config-if)#ip address 3.3.3.2 255.0.0.0

      R3(config-if)#no shutdown


      R3(config-if)#interface fastethernet 0/0

      R3(config-if)#ip address 30.1.1.1 255.0.0.0

      R3(config-if)#no shutdown

      R3(config-if)#exit


      R4(config)#interface serial 4/2

      R4(config-if)#ip address 4.4.4.2 255.0.0.0

      R4(config-if)#no shutdown


      R4(config-if)#interface fastethernet 0/0

      R4(config-if)#ip address 40.1.1.1 255.0.0.0

      R4(config-if)#no shutdown

      R4(config-if)#exit


      R1(config)#ip route 0.0.0.0 0.0.0.0 serial 4/0

      R1(config)#exit


      R2(config)#ip route 1.0.0.0 255.0.0.0 serial 4/0

      R2(config)#ip route 10.0.0.0 255.0.0.0 serial 4/0

      R2(config)#ip route 30.0.0.0 255.0.0.0 serial 4/1

      R2(config)#ip route 3.0.0.0 255.0.0.0 serial 4/1

      R2(config)#ip route 4.0.0.0 255.0.0.0 serial 4/2

      R2(config)#ip route 40.0.0.0 255.0.0.0 serial 4/2


      R3(config)#ip route 0.0.0.0 0.0.0.0 serial 4/1

      R3(config)#exit


      R4(config)#ip route 0.0.0.0 0.0.0.0 serial 4/2

      R4(config)#exit



      R1#ping 40.1.1.1

      Type escape sequence to abort.

      Sending 5, 100-byte ICMP Echos to 40.1.1.1, timeout is 2 seconds:

      !!!!!

      Success rate is 100 percent (5/5), round-trip min/avg/max = 24/45/88 ms

      R1#ping 30.1.1.1

      Type escape sequence to abort.

      Sending 5, 100-byte ICMP Echos to 30.1.1.1, timeout is 2 seconds:

      !!!!!

      Success rate is 100 percent (5/5), round-trip min/avg/max = 32/37/40 ms

      R1#ping 20.1.1.1

      Type escape sequence to abort.

      Sending 5, 100-byte ICMP Echos to 20.1.1.1, timeout is 2 seconds:

      !!!!!

      Success rate is 100 percent (5/5), round-trip min/avg/max = 16/20/36 ms


      R1(config)#interface tunnel 4321

      R1(config-if)#ip address 192.168.1.1 255.255.255.0

      R1(config-if)#tunnel source 1.1.1.1

      R1(config-if)#tunnel mode gre multipoint

      *May 27 12:15:21.279: %LINEPROTO-5-UPDOWN: Line protocol on Interface Tunnel4321, changed state to up

       R1(config-if)#ip nhrp network-id 1

      R1(config-if)#exit


      R3(config)#interface tunnel 4321

      R3(config-if)#ip address 192.168.1.2 255.255.255.0

      R3(config-if)#tunnel source 3.3.3.2

      R3(config-if)#tunnel mode gre multipoint

      *May 27 12:19:21.451: %LINEPROTO-5-UPDOWN: Line protocol on Interface Tunnel4321, changed state to up

      R3(config-if)#ip nhrp network-id 3

      R3(config-if)# ip nhrp map 192.168.1.1 1.1.1.1

      R3(config-if)#ip nhrp nhs 192.168.1.1

      R3(config)#end


      R4(config)#interface tunnel 4321

      R4(config-if)#ip address 192.168.1.3 255.255.255.0

      R4(config-if)#tunnel source 4.4.4.2

      R4(config-if)#tunnel mode gre multipoint

      *May 27 12:27:05.091: %LINEPROTO-5-UPDOWN: Line protocol on Interface Tunnel4321, changed state to up

      R4(config-if)#ip nhrp network-id 4

      R4(config-if)#ip nhrp map 192.168.1.1 1.1.1.1

      R4(config-if)#ip nhrp nhs 192.168.1.1

      R4(config-if)#exit

      R4(config)#end


      R1(config)#router eigrp 4321

      R1(config-router)#network 192.168.1.0

      R1(config-router)#network 10.0.0.0

      R1(config-router)#no auto-summary

      R1(config-router)#exit


      R3(config)#router eigrp 4321

      R3(config-router)#network 192.168.1.0

      R3(config-router)#network 10.0.0.0

      R3(config-router)#no auto-summary

      R3(config-router)#exit


      R4(config)#router eigrp 4321

      R4(config-router)#network 192.168.1.0

      R4(config-router)#network 40.0.0.0

      R4(config-router)#no auto-summary

      R4(config-router)#exit


      R1(config)#interface tunnel 4321

      R1(config-if)#ip nhrp map multicast dynamic

      R1(config-if)#exit


      R1(config)#interface tunnel 4321

      R1(config-if)#no ip split-horizon eigrp 4321

      R1(config-if)#exit


      R1(config)#interface tunnel 4321

      R1(config-if)#no ip next-hop-self eigrp 4321


      *May 27 12:51:44.351: %DUAL-5-NBRCHANGE: EIGRP-IPv4 4321: Neighbor 192.168.1.2 (Tunnel4321) is up: new adjacency

      *May 27 12:52:53.611: %DUAL-5-NBRCHANGE: EIGRP-IPv4 4321: Neighbor 192.168.1.3 (Tunnel4321) is up: new adjacency

      R1(config-if)#end


      R3(config)#interface tunnel 4321

      R3(config-if)#ip nhrp map multicast 1.1.1.1

      R3(config-if)#ip nhrp map multicast 4.4.4.2

      *May 27 12:52:05.019: %DUAL-5-NBRCHANGE: EIGRP-IPv4 4321: Neighbor 192.168.1.3 (Tunnel4321) is up: new adjacency

      R3(config-if)#end


      R4(config)#interface tunnel 4321

      R4(config-if)#ip nhrp map multicast 3.3.3.2

      R4(config-if)#ip nhrp map multicast 1.1.1.1

      R4(config-if)#exit

      {( if you get any error msg please shutdown physical interfaces and tunnel interface and restart the interfaces) Command SHUTDOWN and NO SHUTDOWN}


      R4#show DMVPN

      Legend: Attrb --> S - Static, D - Dynamic, I - Incomplete

              N - NATed, L - Local, X - No Socket

              # Ent --> Number of NHRP entries with same NBMA peer

              NHS Status: E --> Expecting Replies, R --> Responding, W --> Waiting

              UpDn Time --> Up or Down Time for a Tunnel

      ==========================================================================

       

      Interface: Tunnel4321, IPv4 NHRP Details

      Type:Spoke, NHRP Peers:2,

       

       # Ent  Peer NBMA Addr Peer Tunnel Add State  UpDn Tm Attrb

       ----- --------------- --------------- ----- -------- -----

           1 1.1.1.1             192.168.1.1    UP 00:15:50     S

           1 3.3.3.2             192.168.1.2    UP 00:15:30     D

       

      R4#show IP NHRP

      192.168.1.1/32 via 192.168.1.1

         Tunnel4321 created 00:16:09, never expire

         Type: static, Flags: used

         NBMA address: 1.1.1.1

      192.168.1.2/32 via 192.168.1.2

         Tunnel4321 created 00:15:41, expire 01:44:18

         Type: dynamic, Flags: router used

         NBMA address: 3.3.3.2

      192.168.1.3/32 via 192.168.1.3

         Tunnel4321 created 00:15:41, expire 01:44:18

         Type: dynamic, Flags: router unique local

         NBMA address: 4.4.4.2

          (no-socket)


      R4(config-if)#do show ip route eigrp 

      Gateway of last resort is 0.0.0.0 to network 0.0.0.0

       

      D     10.0.0.0/8 [90/26882560] via 192.168.1.1, 00:00:54, Tunnel4321

      D     30.0.0.0/8 [90/26882560] via 192.168.1.2, 00:00:32, Tunnel4321

      R4(config-if)#end



      R4#ping 10.1.1.1

      Type escape sequence to abort.

      Sending 5, 100-byte ICMP Echos to 10.1.1.1, timeout is 2 seconds:

      !!!!!

      Success rate is 100 percent (5/5), round-trip min/avg/max = 32/40/44 ms

      R4#ping 30.1.1.1

      Type escape sequence to abort.

      Sending 5, 100-byte ICMP Echos to 30.1.1.1, timeout is 2 seconds:

      !!!!!

      Success rate is 100 percent (5/5), round-trip min/avg/max = 12/21/40 ms


       

      R4#traceroute 10.1.1.1

      Type escape sequence to abort.

      Tracing the route to 10.1.1.1

      VRF info: (vrf in name/id, vrf out name/id)

        1 192.168.1.1 56 msec 64 msec 20 msec


      R4#traceroute 30.1.1.1

      Type escape sequence to abort.

      Tracing the route to 30.1.1.1

      VRF info: (vrf in name/id, vrf out name/id)

        1 192.168.1.2 20 msec 36 msec 32 msec


      R1#traceroute 30.1.1.1

      Type escape sequence to abort.

      Tracing the route to 30.1.1.1

      VRF info: (vrf in name/id, vrf out name/id)

        1 192.168.1.2 20 msec 48 msec 28 msec

      R1#traceroute 40.1.1.1

      Type escape sequence to abort.

      Tracing the route to 40.1.1.1

      VRF info: (vrf in name/id, vrf out name/id)

        1 192.168.1.3 20 msec 24 msec 44 msec


      R3#show dmvpn

      Legend: Attrb --> S - Static, D - Dynamic, I - Incomplete

              N - NATed, L - Local, X - No Socket

              # Ent --> Number of NHRP entries with same NBMA peer

              NHS Status: E --> Expecting Replies, R --> Responding, W --> Waiting

              UpDn Time --> Up or Down Time for a Tunnel

      ==========================================================================

       

      Interface: Tunnel4321, IPv4 NHRP Details

      Type:Spoke, NHRP Peers:2,

       

       # Ent  Peer NBMA Addr Peer Tunnel Add State  UpDn Tm Attrb

       ----- --------------- --------------- ----- -------- -----

           1 1.1.1.1             192.168.1.1    UP 00:09:29     S

           1 4.4.4.2             192.168.1.3    UP 00:00:58     D


       

       R3#traceroute 10.1.1.1

      Type escape sequence to abort.

      Tracing the route to 10.1.1.1

      VRF info: (vrf in name/id, vrf out name/id)

        1 192.168.1.1 16 msec 36 msec 16 msec


      R3#traceroute 40.1.1.1

      Type escape sequence to abort.

      Tracing the route to 40.1.1.1

      VRF info: (vrf in name/id, vrf out name/id)

        1 192.168.1.3 12 msec 48 msec 40 msec
      Read More

      How to configure EIGRP and OSPF over DMVPN Phase 1 & 2?

      Internetworks April 26, 2021


      As we already discuss Phase 1 is Not used nowadays, In phase 1 we use NHRP so that spokes can register themselves with the hub (NHRP needed for spokes to register with hub). The hub is the only router that is using a multipoint GRE (mGRE) interface, all spokes will be using regular point-to-point GRE tunnel interfaces. No spokes hub and spokes topology were dynamic IP addresses on the spokes may be used. All your traffic goes through the hub. This means that there will be no direct spoke-to-spoke communication; all traffic has to go through the hub.

      Before we start our configuration of EIGRP and OSPF over DMVPN, we need to understand few things about EIGRP and OSPF.

      The IP NHRP map multicast dynamic enables the forwarding of multicast traffic across the tunnel to dynamic spokes. This is usually required by the routing protocol as OSPF and EIGRP. In most cases, DMVPN is accompanied by a routing protocol to send and receive dynamic updates about the private networks. The IP NHRP map multicast dynamic command is not required if we are using static NHRP mappings.

      EIGRP routers will not be advertising back on the same interface because of the split horizon rules the split-horizon rule prohibits a router from advertising a route through an interface that the router itself uses to reach the destination. To disable the split-horizon behavior, use the { NO IP SPLIT-HORIZON EIGRP AS-number interfaces command. Split horizon behavior is turned on by default. When you change the EIGRP split-horizon setting on an interface, it reset all adjacencies with EIGRP neighbors reachable over that interface. The split horizon should only be disabled on the hub site in a hub and spoke network.

      Disabling split-horizon on the spokes radically increases EIGRP memory consumption on the hub router and the amount of traffic generated on the spoke routers.

      By default, OSPF handles tunnel interface as a point-to-point interface no matter even if you configure multipoint GRE.  we will get neighbourship goes down messages repeatedly. to over this issue, we need to change the default setting we will see in this OSPF LAB.


      Let see the configuration-_

      Topology:-
      Read More
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      About me

      I am a CCIE Technical Instructor/Network, consultant. I am having experience of ranging from operating and maintaining PCs and peripherals to network control programs for multi-faceted data communication networks in LAN, MAN, and WAN environments.

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