DCC server or Client suite to us?

Mathew Thomas mathew.thomas@rmit.edu.au
Thu Jul 6 01:01:30 UTC 2006


Thanks Vernon.
I believe, I can upgrade DCC alone without upgrading SpamAssassin &
MimeDefang. Upgrading everything will take more time.  Currently I am
getting al lot of the following error:

Jul  5 02:05:43 hostname dccproc[19395]: [ID 702911 mail.error]
continue not asking DCC 13 seconds after failure
Jul  5 02:05:46 hostname dccproc[19401]: [ID 702911 mail.error]
continue not asking DCC 10 seconds after failure
Jul  5 02:05:48 hostname dccproc[19404]: [ID 702911 mail.error]
continue not asking DCC 8 seconds after failure
Jul  5 02:05:48 hostname dccproc[19406]: [ID 702911 mail.error]
continue not asking DCC 8 seconds after failure

The current version of DCC on mail gateway is 1.2.50. I will upgrade
DCC on all 4 gateways and set up a  DCC server on a separate m/c.

Regards
Mathew


>>> Vernon Schryver <vjs@calcite.rhyolite.com> 5/07/06 23:25:27 >>>
> From: "Mathew Thomas" 

> We have got four mail gateways - Total mail per day on four gateways
> together is 400,000 to 450,000 (50,000 -100,000 outbound, 300,000 -
> 350,000 inbound)
>
> Should I set up our own DCC server or can I use the public dcc
servers?

400K mail messages/day is above the 100,000 threshold at which a local
DCC server is justified.
It is high enough that it will trigger some of the DoS defenses
in the public DCC servers.  Those start with delaying responses and
then ignoring requests entirely.  At 400K/day, some of your requests
should be ignored.

> Can I do it on one of the gateway? 

The DCC server process, dccd, uses needs trivial CPU cycles but at
least 3 GByte of RAM.  4 GByte is not too much.  If one of your
gateways
has that much RAM to spare, it could run dccd.
A DCC server also needs as much as 12 GByte of disk space, but that is
also trivial today.


>                                    If I needed to set it up on one
of
> the gateway, how can I set it up so that all four mail gateways can
use
> it?

/var/dcc/map contains the names and IP addresses of the DCC servers
known to a DCC client such as one of your gateways.  It is best to
teach a DCC client about a local server with a command like:

   cdcc "add host.example.com  RTT-1000 ms  32768  secret"

where secret is the password for client-ID 32768 in /var/dcc/ids on
the
DCC servers.


A DCC server needs a server-ID and 3-4 flooding peers to receive
checksums of recently seen bulk mail.  I can provide those.


Vernon Schryver    vjs@rhyolite.com 
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