Le Cloud de Christophe BOUCETTA (MVP Lync/Skype for Business, CCNP Voice, CCNP Collaboration)

Voici le blog sur les communications unifiées

[Cisco] Status des messages ISAKMP (phase 1)

Voici un petit status sur les messages ISAKMP qui peuvent remonter dans une commande "show crypto isakmp sa" lorsque l'on souhaite debugger un problème de vpn :

ASA ISAKMP STATES

  • MM_WAIT_MSG2
    Initial DH public key sent to responder. Awaiting initial contact reply from other side.

    If stuck here it usually means the other end is not responding. This could be due to no route to the far end or the far end does not have ISAKMP enabled on the outside or the far end is down.
  • MM_WAIT_MSG3
    Both peers have agreed on the ISAKMP policies. Awaiting exchange of keyring information.

    Hang up’s here may be due to mismatch device vendors, a router with a firewall in the way, or even ASA version mismatches.
  • MM_WAIT_MSG4
    In this step the pre-share key hashes are exchanged. They are not compared or checked, only sent. If one side sends a key and does not receive a key back, this is where the tunnel will fail.
    I have seen the tunnel fail at this step due to the remote side having the wrong Peer IP address. Hang up’s here may also be due to mismatch device vendors, a router with a firewall in the way, or even ASA version mismatches.
  • MM_WAIT_MSG5
    This step is where the devices exchange pre-shared keys.
    If the pre-shared keys do not match it will stay at this MSG. I have also seen the tunnel stop here when NAT Traversal was on when it needed to be turned off.
  • MM_WAIT_MSG6
    This step is where the devices exchange pre-shared keys.
    If the pre-shared keys do not match it will stay at this MSG. I have also seen the tunnel stop here when NAT Traversal was on when it needed to be turned off.
    However, if the state goes to MSG6 then the ISAKMP gets reset that means phase 1 finished but phase 2 failed. Check that IPSEC settings match in phase 2 to get the tunnel to MM_ACTIVE.
  • AM_ACTIVE / MM_ACTIVE
    The ISAKMP negotiations are complete. Phase 1 has successfully completed.

PIX ISAKMP STATES

  • MM_NO_STATE
  • ISAKMP SA has been created but nothing else has happened yet.

  • MM_SA_SETUP
  • The peers have agreed on parameters for the ISAKMP SA.

  • MM_KEY_EXCH
  • The peers have exchanged Diffie-Hellman public keys and have generated a shared secret. The I SAKMP SA remains unauthenticated.

  • MM_KEY_AUTH
  • The ISAKMP SA has been authenticated. If the router initiated this exchange, this state trans itions immediately to QM_IDLE and a Quick mode exchange begins.

  • AG_NO_STATE
  • The ISAKMP SA has been created but nothing else has happened yet.

  • AG_INIT_EXCH
  • The peers have done the first exchange in Aggressive mode but the SA is not authenticated.

  • AG_AUTH
  • The ISAKMP SA has been authenticated. If the router initiated this exchange, this state transitions immediately to QM_IDLE and a Quick mode exchange begins.

  • QM_IDLE
  • The ISAKMP negotiations are complete. Phase 1 successfully completed. It remains authenticated with its peer and may be used for subsequent Quick mode exchanges.

Errors With ISAKMP Or Phase 1 Establishing

A very common problem is phase 1 not establishing correctly.

  • Verify ISAKMP parameters match exactly.
  • Verify pre-shared-keys match exactly.
  • Check that each side has a route to the peer address that you are trying to form a tunnel with.
  • Verify ISAKMP is enabled on the outside interfaces.
  • Is ESP traffic permitted in through the outside interface?
  • Is UDP port 500 open on the outside ACL?
  • Some situations require that UDP port 4500 is open for the outside.
Facebook Like
Anonymous