[Freeipa-users] Not able to get kerberos ticket from keytab

Fri Feb 26 08:15:17 UTC 2016

On 26/02/16 08:56, David Kupka wrote:
> On 26/02/16 02:22, Teik Hooi Beh wrote:
>> Hi,
>>
>> I have manged to deployed 1 ipa master and 1 ipa client with success on
>> centos 7.2 with freeipa v4.2. I also managed to create user and set
>> sshd-rules to for ttester user and also successfully get krb ticket
>> using *kinit
>> ttester at EXAMPLE.MY*. I am trying to deploy password-less SSH login with
>> kerberos using the following guide  (
>> https://uz.sns.it/~enrico/wordpress/2014/03/password-less-ssh-login-with-kerberos/)
>>
>> -
>>
>> snippet -
>>
>>
>>
>> *$ ktutil ktutil: add_entry -password -p ttester at EXAMPLE.MY -k 1 -e
>> aes256-cts-hmac-sha1-96 ktutil: write_kt keytab*
>>
>> When I tried *kinit -kt keytab ttester at EXAMPLE.MY*, I get *"**kinit:
>> Password incorrect while getting initial credentials"*
>> Doing a trace using KRB5_TRACE on both calls
>>
>> *1. KRB5_TRACE=/dev/stderr kinit ttester at EXAMPLE.MY*
>> 27242] 1456447025.219676: Getting initial credentials for
>> ttester at EXAMPLE.MY
>> [27242] 1456447025.222070: Sending request (164 bytes) to EXAMPLE.MY
>> [27242] 1456447025.222223: Resolving hostname node1.example.my
>> [27242] 1456447035.238004: Initiating TCP connection to stream
>> 192.168.38.2:88
>> [27242] 1456447035.238675: Sending TCP request to stream 192.168.38.2:88
>> [27242] 1456447035.241248: Received answer (337 bytes) from stream
>> 192.168.38.2:88
>> [27242] 1456447035.241257: Terminating TCP connection to stream
>> 192.168.38.2:88
>> [27242] 1456447035.241377: Response was from master KDC
>> [27242] 1456447035.241437: Received error from KDC:
>> -1765328359/Additional
>> pre-authentication required
>> [27242] 1456447035.241484: Processing preauth types: 136, 19, 2, 133
>> [27242] 1456447035.241499: Selected etype info: etype aes256-cts, salt
>> "s`GD^,#=cA:Vr9hD", params ""
>> [27242] 1456447035.241504: Received cookie: MIT
>> Password for ttester at EXAMPLE.MY:
>> [27242] 1456447062.215750: AS key obtained for encrypted timestamp:
>> aes256-cts/73C6
>> [27242] 1456447062.215815: Encrypted timestamp (for 1456447062.215315):
>> plain 301AA011180F32303136303232363030333734325AA1050203034913, encrypted
>> F9A2E97E916FC14D141690E151A25DCC00168361179C7F0ACDA94C7F58F3D50429780A5608A6B8623E355F2A5BD676F6FA5272D38FD05C8B
>>
>> [27242] 1456447062.215942: Preauth module encrypted_timestamp (2) (real)
>> returned: 0/Success
>> [27242] 1456447062.215948: Produced preauth for next request: 133, 2
>> [27242] 1456447062.215965: Sending request (257 bytes) to EXAMPLE.MY
>> [27242] 1456447062.216010: Resolving hostname node1.example.my
>> [27242] 1456447072.229254: Initiating TCP connection to stream
>> 192.168.38.2:88
>> [27242] 1456447072.229655: Sending TCP request to stream 192.168.38.2:88
>> [27242] 1456447072.236955: Received answer (722 bytes) from stream
>> 192.168.38.2:88
>> [27242] 1456447072.236974: Terminating TCP connection to stream
>> 192.168.38.2:88
>> [27242] 1456447072.237080: Response was from master KDC
>> [27242] 1456447072.237117: Processing preauth types: 19
>> [27242] 1456447072.237125: Selected etype info: etype aes256-cts, salt
>> "s`GD^,#=cA:Vr9hD", params ""
>> [27242] 1456447072.237131: Produced preauth for next request: (empty)
>> [27242] 1456447072.237140: AS key determined by preauth: aes256-cts/73C6
>> [27242] 1456447072.237199: Decrypted AS reply; session key is:
>> aes256-cts/2A71
>> [27242] 1456447072.237216: FAST negotiation: available
>> [27242] 1456447072.237236: Initializing KEYRING:persistent:1000:1000 with
>> default princ ttester at EXAMPLE.MY
>> [27242] 1456447072.237275: Storing ttester at EXAMPLE.MY ->
>> krbtgt/EXAMPLE.MY at EXAMPLE.MY in KEYRING:persistent:1000:1000
>> [27242] 1456447072.237330: Storing config in KEYRING:persistent:1000:1000
>> for krbtgt/EXAMPLE.MY at EXAMPLE.MY: fast_avail: yes
>> [27242] 1456447072.237345: Storing ttester at EXAMPLE.MY ->
>> krb5_ccache_conf_data/fast_avail/krbtgt\/EXAMPLE.MY\@EXAMPLE.MY at X-CACHECONF:
>>
>> in KEYRING:persistent:1000:1000
>> [27242] 1456447072.237371: Storing config in KEYRING:persistent:1000:1000
>> for krbtgt/EXAMPLE.MY at EXAMPLE.MY: pa_type: 2
>> [27242] 1456447072.237380: Storing ttester at EXAMPLE.MY ->
>> krb5_ccache_conf_data/pa_type/krbtgt\/EXAMPLE.MY\@EXAMPLE.MY at X-CACHECONF:
>> in KEYRING:persistent:1000:1000
>>
>> *2. KRB5_TRACE=/dev/stderr kinit -kt keytab ttester at EXAMPLE.MY*
>> [27248] 1456447236.144685: Getting initial credentials for
>> ttester at EXAMPLE.MY
>> [27248] 1456447236.147107: Looked up etypes in keytab: aes256-cts
>> [27248] 1456447236.147255: Sending request (164 bytes) to EXAMPLE.MY
>> [27248] 1456447236.147381: Resolving hostname node1.example.my
>> [27248] 1456447246.161528: Initiating TCP connection to stream
>> 192.168.38.2:88
>> [27248] 1456447246.161970: Sending TCP request to stream 192.168.38.2:88
>> [27248] 1456447246.164772: Received answer (337 bytes) from stream
>> 192.168.38.2:88
>> [27248] 1456447246.164791: Terminating TCP connection to stream
>> 192.168.38.2:88
>> [27248] 1456447246.164904: Response was from master KDC
>> [27248] 1456447246.164943: Received error from KDC:
>> -1765328359/Additional
>> pre-authentication required
>> [27248] 1456447246.164987: Processing preauth types: 136, 19, 2, 133
>> [27248] 1456447246.164997: Selected etype info: etype aes256-cts, salt
>> "s`GD^,#=cA:Vr9hD", params ""
>> [27248] 1456447246.165001: Received cookie: MIT
>> [27248] 1456447246.165142: Retrieving ttester at EXAMPLE.MY from FILE:keytab
>> (vno 0, enctype aes256-cts) with result: 0/Success
>> [27248] 1456447246.165166: AS key obtained for encrypted timestamp:
>> aes256-cts/0A17
>> [27248] 1456447246.165210: Encrypted timestamp (for 1456447246.164647):
>> plain 301AA011180F32303136303232363030343034365AA1050203028327, encrypted
>> C092E6C29FC1CD794625CF12162D18767A68D1728E6C2ADC1F50492D6605E039B664213C29767715E04B3CA8D97EBD691BBF40B76370C9FA
>>
>> [27248] 1456447246.165224: Preauth module encrypted_timestamp (2) (real)
>> returned: 0/Success
>> [27248] 1456447246.165228: Produced preauth for next request: 133, 2
>> [27248] 1456447246.165239: Sending request (257 bytes) to EXAMPLE.MY
>> [27248] 1456447246.165253: Resolving hostname node1.example.my
>> [27248] 1456447256.178637: Initiating TCP connection to stream
>> 192.168.38.2:88
>> [27248] 1456447256.179456: Sending TCP request to stream 192.168.38.2:88
>> [27248] 1456447256.184929: Received answer (167 bytes) from stream
>> 192.168.38.2:88
>> [27248] 1456447256.184941: Terminating TCP connection to stream
>> 192.168.38.2:88
>> [27248] 1456447256.185043: Response was from master KDC
>> [27248] 1456447256.185065: Received error from KDC: -1765328353/Decrypt
>> integrity check failed
>> kinit: Password incorrect while getting initial credentials
>>
>>> From the 2 trace I notice the return bytes on return from calling using
>> keytab is only 167 bytes compare to 722 bytes. Does anybody know the
>> reasons or could point me to where I could debug further?
>>
>> Thanks
>>
>>
>>
>
> Hello!
>
> I don't know why it does not work with ktutil but I've find other way
> how to get keytab for a user:
>
> $ kinit ttester
> $ ipa-getkeytab -p ttester at EXAMPLE.TEST -k ttester.keytab -e
> aes256-cts-hmac-sha1-96
> $ kdestroy ttester
> $ kinit ttester at EXAMPLE.TEST -kt ttester.keytab
>
> HTH,
>

Oh, I forget to mention that this also sets random krbPrincipalKey for 
the user so you can kinit only with the keytab. ipa-getkeytab has also 
option -r (--retrive) that should not change krbPrincipalKey but for 
some reason user is not allowed to retrieve it.
You can of course add ACI to allow that but I would not do it because 
there's probably good reason why it's forbidden by default.

-- 
David Kupka