[ntp:questions] Re: autokey setup with GQ Identity Scheme

user at domain.invalid user at domain.invalid
Wed May 31 15:37:42 UTC 2006


Very thorough. This of course is the acid test for Autokey - symmetric 
modes and something other than IFF. GQ does have a few quirks, as the 
public group key is embedded in the certificate extension field. If you 
watch the protocol exchange with the -d trace, you might get a surprise. 
The protocol is awesome, as the passive peer has first to authenticate 
the active one, then the active peer has to authenticate the passive 
one. It takes several minutes. Don't use iburst; that really confuses 
the protocol.

The acid test is, once the peers have completed the dance and packets 
have only the MAC, restart one of the peers and verify the protocol 
recovers, then restart the other peerb and verify the protocol recovers. 
Note that restarting the active peer forces the passive one to 
demobilize and then remobilize. Awesome.


Steve Kostecke wrote:
> Jean-Francois Malouin wrote:
>>After a few days of reading all sort of doc (mainly
>>http://ntp.isc.org/bin/view/Support/ConfiguringAutokey) I have
>>convinced myself that I'm missing something crucial in my NTP
>>sub-domain setup but I can't put the finger on it... I'll be quite
>>happy to give further output/debug to anyone who can help and I 
>>appologize if this is too long but it has been a few very frustating
> I ran some tests this afternoon and here's what I learned:
> 1. You need a "relatively" recent ntp-dev snapshot; it must support the
> 'crypto ident' configuration option.
> 2. You must use a shared, or common, password.
> 3. Generate GQ parameters on each peer:
> 	ntp-keygen -T -G -p common_password
> (append '-q common_password' to the above line if you've already
> generated the host parameters.)
> 4. 'cross copy' the GQPar files between the systems which will be peers
> and create the sum-link. In a two peer trust group you would see the
> following in each peers' keys dir (in addition to the host parameters):
> ntpkey_GQpar_peer1.xxxxxxxxxx
> ntpkey_GQpar_peer2.xxxxxxxxxx
> ntpkey_gq_peer1 -> ntpkey_GQpar_peer1.xxxxxxxxxx
> ntpkey_gq_peer2 -> ntpkey_GQpar_peer2.xxxxxxxxxx
> 5. In the ntp.conf for each peer:
> 	* add a 'crypto ident <hostname>' line; where <hostname>
> 	  is the hostname used in the filename of that system's
> 	  ntpkey_GQpar_hostname.xxxxxxxxxx file. This line tells ntpd
> 	  which crypto identity to assume.
> 	* add a 'peer other_peer_hostname_or_ip_address autokey' line.
> 6. (Re-)Start both ntpds and _be patient_. Use something like 'watch
> -n5 ntpq -pcas' (for each peer) to watch the associations form. If the
> authentication is successful you should see the 'other_peer' information
> start to appear in the 'ntpq -p' billboard for one of the peers after
> 1 or 2 poll periods (64 sec) have expired. It may take a few more poll
> periods before both peers show an established association. You should
> see an 'ok' in the auth column for the 'other peer'.
> 7. Use ntpq to verify the crypto status. Here's an example:
> | steve at stasis:~$ ntpq
> | ntpq> as
> | 
> | ind assID status  conf reach auth condition  last_event cnt
> | ===========================================================
> |   1 18765  f034   yes   yes   ok     reject   reachable  3
> |   2 18766  9014   yes   yes  none    reject   reachable  1
> |   3 18767  9614   yes   yes  none  sys.peer   reachable  1
> In this case assID 18765 is my Authenticated Peer. So...
> | ntpq> ps 18765
> | assID=18765 status=f034 reach, conf, auth, 3 events, event_reach,
> <snip>
> | hostname="rover", signature="md5WithRSAEncryption", flags=0x87f43,
> | trust="rover", initsequence=62, initkey=0xc293cd34,
> | timestamp=200605302026
> The flags shown above (flags=0x87f43) mean the following (see
> ./include/ntp_crypto.h):
> #define CRYPTO_FLAG_ENAB  0x0001 /* crypto enable */
> #define CRYPTO_FLAG_TAI   0x0002 /* leapseconds table */
> #define CRYPTO_FLAG_GQ    0x0040 /* GQ identity scheme */
> #define CRYPTO_FLAG_VALID 0x0100 /* public key verified */
> #define CRYPTO_FLAG_VRFY  0x0200 /* identity verified */
> #define CRYPTO_FLAG_PROV  0x0400 /* signature verified */
> #define CRYPTO_FLAG_AGREE 0x0800 /* cookie verifed */
> #define CRYPTO_FLAG_AUTO  0x1000 /* autokey verified */
> #define CRYPTO_FLAG_SIGN  0x2000 /* certificate signed */
> #define CRYPTO_FLAG_LEAP  0x4000 /* leapseconds table verified */
> I've not tested this beyond two peers, so I don't know what will happen
> when you add the third.

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