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r1 - 2004-08-15 - 04:07:00 - SteveKosteckeYou are here: NTP >  Support Web > ConfiguringAutokey > ConfiguringAutokeyDev
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Are you using Autokey in production? If so, please contact Harlan - he's got some questions for you.

Discussion of ConfiguringAutokey

The checklist

A short checklist to setup a ntp server Alice and a client Bob to use autokey with the IFF identity scheme:
1) On both Alice and Bob, add two lines to your ntp.conf:
### ntp.conf
[...]
#added lines to switch on autokey usage:
crypto pw littlesecret
keysdir /etc/ntp/

And add the server line for Alice to Bob's ntp.conf, including the autokey parameter:

### ntp.conf of Bob
server Alice autokey
[...]

2) On Alice, create trusted public key and identity scheme parameter file, and use a password with at least 4 characters:

Alice:/etc/ntp# ntp-keygen -T -I -p littlesecret


3) Then copy the file ntpkey_IFFpar_Alice.[timestamp] securely to Bob's keysdir:
Bob:/etc/ntp# scp root@alice:/etc/ntp/ntpkey_IFFpar_Alice.3288592503 /etc/ntp/

4) Create two links in Bob's keysdir:
Bob:/etc/ntp# ln -s ntpkey_IFFpar_Alice.3288592503 ntpkey_iff_Alice
Bob:/etc/ntp# ln -s ntpkey_IFFpar_Alice.3288592503 ntpkey_iff_Bob

5) Restart your ntpd on Alice
6) Restart your ntpd on Bob
7) Sit back, get a beer (or any other beverage you prefer) and - if religous - pray a little prayer

After a while, Bob should accept Alice as his timesource and the world is a better place (well, at least a little bit better).

In order to generate a new public key (you could do this on a monthly basis), use the following command on Alice:

Alice:/etc/ntp# ntp-keygen -T -q littlesecret

-- HeikoGerstung


Additional comments:

Here is an additional comment from Dave:

You might need to automate a scheme for a new user to get an (encrypted) copy of the group key, say by electric mail. I did that for one of our NTP servers as an experiment and proposed that for use by others. It amounts to a procmail recipe that sends back a script containing the encrypted key. The client runs the script and the appropriate magic happens. Of course, it should be done using PGP mail, but I'm not a mail expert here and I was hoping some volunteer would do it properly.

If you really want to have some fun, try the MV identity scheme. Use that scheme if you can't trust the servers, much less the clients, and need to be able for the trusted agent to revoke some client turned terrorist. The mathematics of that scheme is delicious.

Dave

-- HeikoGerstung - 19 Mar 2004

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