FlexVPN - troubleshooting

I would like to share with you very useful commands which can helpful you during your troubleshooting. Instead of checking (sometimes very long) configuration, you can check/compare the same block of configuration between your peers.

1) ikev2 proposal

r5#sh crypto ikev2 proposal
 IKEv2 proposal: IKEV2-PROPOSAL
     Encryption : AES-CBC-128
     Integrity  : SHA512
     PRF        : SHA512
     DH Group   : DH_GROUP_1536_MODP/Group 5
 IKEv2 proposal: default
     Encryption : AES-CBC-256 AES-CBC-192 AES-CBC-128
     Integrity  : SHA512 SHA384 SHA256 SHA96 MD596
     PRF        : SHA512 SHA384 SHA256 SHA1 MD5
     DH Group   : DH_GROUP_1536_MODP/Group 5 DH_GROUP_1024_MODP/Group 2
r5#

From above output you can learn about all available ikev2 proposals. As you see there is one proposal default. You can use it in your config but you can also disable it:

r5(config)#no crypto ikev2 proposal default

you have to first disable the default policy.

r5#sh crypto ikev2 proposal
 IKEv2 proposal: IKEV2-PROPOSAL
     Encryption : AES-CBC-128
     Integrity  : SHA512
     PRF        : SHA512
     DH Group   : DH_GROUP_1536_MODP/Group 5
 IKEv2 proposal: default Disabled
r5#

to enable it again, issue following command:

r5(config)#default crypto ikev2 proposal

2) ikev2 policy

 r5#sh crypto ikev2 policy

 IKEv2 policy : IKEV2-POLICY
      Match fvrf  : global
      Match address local : any
      Proposal    : IKEV2-PROPOSAL

 IKEv2 policy : default
      Match fvrf : any
      Match address local : any
      Proposal    : default
r5#

As with the proposal, you can enable/disable it:

r5(config)#no crypto ikev2 policy default

r5(config)#default crypto ikev2 policy

3) ikev2 profile

r5#sh crypto ikev2 profile

IKEv2 profile: IKEV2-PROFILE
 Ref Count: 3
 Match criteria:
  Fvrf: global
  Local address/interface: none
  Identities:
   address 0.0.0.0
  Certificate maps: none
 Local identity: none
 Remote identity: none
 Local authentication method: pre-share
 Remote authentication method(s): pre-share
 EAP options: none
 Keyring: KEYRING123
 Trustpoint(s): none
 Lifetime: 86400 seconds
 DPD: interval 10, retry-interval 2, periodic
 NAT-keepalive: disabled
 Ivrf: none
 Virtual-template: 1
 AAA EAP authentication mlist: none
 AAA Accounting: none
 AAA group authorization: none
 AAA user authorization: none
r5#

4) transform-set

r5#sh crypto ipsec transform-set
Transform set default: { esp-aes esp-sha-hmac  }
   will negotiate = { Transport,  },

Transform set TS: { esp-256-aes esp-sha512-hmac  }
   will negotiate = { Tunnel,  },

r5#

To enable/disable the default transform-set issue the command:

r5(config)#no crypto ipsec transform-set default

r5(config)#default crypto ipsec transform-set

5) IPsec profile

r5#sh crypto ipsec profile
IPSEC profile IPSEC-PROFILE
        IKEV2 profile IKEV2-PROFILE
        Security association lifetime: 4608000 kilobytes/3600 seconds
        Responder-Only (Y/N): N
        PFS (Y/N): N
        Transform sets={
                TS:  { esp-256-aes esp-sha512-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  } ,
        }

r5#

r5(config)#default crypto ipsec profile

r5(config)#no crypto ipsec profile default