The Coda Distributed Filesystem for Linux
Authenticating to Coda

Bill von Hagen
Monday, October 7, 2002 11:12:44 AM
If you've followed the instructions in the previous section, your
Coda client is now talking to your Coda server, and you should be able
to list the /coda directory on the client ("ls /coda") and see any
files that are located on the data partition that the server is
exporting. If you see output like that in the following example, your
client and server aren't talking correctly:
ls /coda
NOT_REALLY_CODA
In this case, you should check your logs (/var/log/messages, for
system problems, and /vice/srv/SrvLog, for Coda-specific
problems). Unfortunately, debugging every possible problem is outside
the scope of this article, but Coda usually just works.
If you can list the /coda directory on your client and see no files,
the natural thing to do is to want to create a file there and make
sure that you can see it from any and all Coda clients that are
communicating with your server. To do this, you must authenticate to
Coda, which will give you the privileges that you need to actually
create files in a standard Coda filesystem. The Coda filesystem
exported by CMU for Coda testing is specially configured to enable
anyone to read and write there, which--as you might hope--is not the
default configuration of a Coda filesystem. The following shows an
unauthenticated attempt to create a file in /coda:
ls /coda
cp linux-coda-5.0.0.tgz /coda
cp: cannot create regular file `/coda/linux-coda-5.0.0.tgz': Permission denied
A complete discussion of Coda authentication is outside the scope of
this article. Coda provides the au command to create and manage
Coda user accounts and administrative groups. This example will
authenticate as the administrative Coda user that was created during
the server installation procedure discussed in a previous section of
this article.
Authenticating to Coda can be done manually using Coda's clog
command. In production Coda environments, Coda authentication is
typically incorporated into the standard system login process using
PAM or by adding the clog command to a user's login script.
The following example shows using the clog command to
authenticate as the "codaroot" user, which is the Coda system
administration account that was created in the previous section of
this article:
clog codaroot
username: codaroot
Password:
19:24:01 root acquiring Coda tokens!
After authenticating to Coda (known as "acquiring tokens" in
Coda-speak), you should now be able to create a file in the
distributed Coda filesystem, as in the following example.
cp linux-coda-5.0.0.tgz /coda
In this case, no news is good news--the file was correctly copied to
the /coda partition, which is the client's mount point for the Coda
partition that is being exported by your server.
Next: Hoarding Files for Disconnected Operation »