Coda File System

Re: "Newbie" question

From: Jan Harkes <>
Date: Sun, 18 Jul 1999 20:10:22 -0400
On Sun, Jul 18, 1999 at 05:34:49PM -0400, Pete Gonzalez wrote:
> Thanks for the quick reply.  BTW, is this a "bug" or a "feature"?
> It seems kind of unusal to have a daily cronjob that uses the cleartext
> administrator's password.  For example, the server could instead validate
> the client with a simple zero-knowledge authentication scheme such as
> the one described here:

I don't see how that would get the password out of the daily cronjob.
This is from the protocol description:

User -> Host:  U, A = g^a                  (identifies self, a = random number)
Host -> User:  s, B = v + g^b, u           (sends salt, b = random number,
                                            u = t-bit random number)
        User:  x = H(s, p)                 (user enters password)
However, it is interesting that the file wouldn't have to
contain xor-ed cleartext passwords anymore. We currently need them
because of the shared secret authentication/key exchange.

> Is the 25-hour rule inherited from AFS?

No, I believe that came from kerberos. In fact kerberized machines have
a srvtab file which is as far as I know used as some `unlimited and
unsecured token' for daemons. But I'm not completely sure how it is
used, maybe it is used by a daemon like a password to get new session

You could mimic this by using the tokentool to create a token which is
valid for the next year or so, and from the cron start *)
    clog -fromfile /etc/codatoken

Not that I recommend this, the current scheme with a cleartext password
in the cronjob obtains a new session key every day. And as soon as it is
known that a daemon password has been compromised it can be changed and
any `illegaly' obtained tokens can only be used for a maximum of 25
hours. Also a daemon shouldn't need to be given Coda administrator rights.


*) or "cat /etc/codapassword | clog -pipe ftp/web/mail", which does get
   a new session key. This is just as insecure as putting the password
   in the cronjob, but simplifies changing the password on a group of
Received on 1999-07-18 20:11:22