dccm and dccd questions and answers

Vernon Schryver vjs@calcite.rhyolite.com
Sat Oct 20 03:25:45 UTC 2001

These are some questions and answers from someone getting dccd and dccm going.
With his permission, I'm putting them in the mailing list archive.

> ...
>                    dccd, and dccm running on my system.  Sendmail seems to
> be talking to dccm as a milter process.  I'm running dccm with the -W flag
> for now since I want to be sure not to reject mail until I understand if I'm
> properly configured. But I don't see X-DCC headers added to incoming mail.
> ...

I've just added the following to the dccm man page:

   Since the checksums of messages that are white listed locally by -W or by
   -w file are not reported to the DCC server, dccm knows nothing about the
   total recipient counts for their checksums and so cannot add an X-DCC
   header line.  Sendmail does not tell dccm about messages that are not re-
   ceived by sendmail via SMTP, including messags submitted locally and re-
   ceived via UUCP, and so they also do not receive X-DCC header lines.

Unless you give it rejection thresholds with -t (or with -R to start-dccm),
dccm rejects nothing, but at most logs messages and adds header lines.

`dccm -A IGNORE` would turn off rejections that -t might otherwise cause.

> I don't see any log/tracing controls on dccm that would let me tell what's
> going on.  Is there a way to get dccm to log something?  I can always use
> ktrace I suppose.  I looked at dblist hoping perhaps I could uise it to show
> me entries created locally, but didn't see a way.

`dblist -v | tail` will show the most recently created entries.
But since you're using -W, dccm is not reporting any checksums and
so dccd is not added any locally detected checksums.

`dccm -dddd` causes various  debugging messages, but there is no equivalent
to dccd tracing as with `cdcc "id 1234; trace all on"`

Dccm logs messages with checksum thresholds above the -t values.
For example, `dccm -t all,0` would log all messages, except 
those locally whitelisted.

> One other thing.  I'm not clear on which server dccm will query/communicate
> with.  I thought it might be the default server in the map file so I tried
> to change this by running cdcc, delete'ing both servers, then adding
> localhost before rhyolite.  But I still seem to get your server when I do
> something like "cdcc stats".  Does that mean my default server is still
> yours and not the one at localhost?  How do I configure my machine so that
> dccm communicates locally?  Or do I misunderstand things?  (I thought it
> would best for dccm to communicate with localhost and then have localhost
> flood results to its neighbors.)

dccm, dccproc, and even cdcc use the "current best" DCC server.
The best DCC server is the one with the lowest measured RTT, as adjusted 
with the RTT+adj or RTT-adj kludge.
The DCC client library continually measures the RTT to the current 
best server and periodically pokes all known servers to keep up with
their RTT's (as well as any changes in IP address).


> Hmm, wonder why localhost has such a bad RTT; that's 2 seconds.  Sounds like
> some timer going off.

Dccd delays answers to anonymous DCC clients by the value of the -u option.
It's default value is 2 seconds.  Since you have not told your DCC client
about a good DCC client ID and password, it is using the anonymous ID, 1,
and getting delayed answers.

I guess somewhere it should be written that running a DCC server usually
involves maintaining client IDs and passwords in the /var/dcc/ids file.
I could allocate a client ID for you in my /var/dcc/ids file and we
could try to keep your file and mine consistent.  In the earliest days
of the DCC, that was necessary.  I found it too much work, and so went
to the other extreme of every DCC server using an independent set
of client IDs.

Note that as the section on "Client and Server IDs" in `man dcc` says,
client IDs start at 32768.

You could also run dccd with -u 0, perhaps with `start-dccm ... -a '-u0' ...`
or with the following line from my /var/dcc/dcc_conf file

Vernon Schryver    vjs@rhyolite.com

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