DCC client issues

Vernon Schryver vjs@calcite.rhyolite.com
Wed Apr 14 19:36:17 UTC 2010

> From: Eric Chenard <echenard@uottawa.ca>

>                                        Is it possible the dccifd process
> gets overwhelmed and stops responding and so amavis just gives up on the
> DCC check?

The DCC clients, dccm, dccifd, and dccproc, are rarely themselves "slow"
compared to filters that check for viruses or malware.
However, if the DCC servers used by a DCC client is slow, the client
can appear to be slow.  If the DCC server is slow enough or not responding,
the DCC client will give up and stop asking and adding X-DCC headers for
an exponentially increasing times.   When this happens, there should 
be "continue not asking" complaints in logs from the client.

The /var/dcc/map file should always list more than one DCC server.
It often makes sense for non-commercial DCC installations to use
the public DCC servers as backups when a local server is busy with
dbclean or simply down.  That can be done with

    cdcc "add dcc1.dcc-servers.net RTT+1000 ms"
    cdcc "add dcc2.dcc-servers.net RTT+1000 ms"
    cdcc "add dcc3.dcc-servers.net RTT+1000 ms"
    cdcc "add dcc4.dcc-servers.net RTT+1000 ms"
    cdcc "add dcc5.dcc-servers.net RTT+1000 ms"

Commercial installations should use the backup commercial DCC servers.

See also the fix-map script in /var/dcc/build/dcc/homedir
after running /var/dcc/updatedcc.

Vernon Schryver    vjs@rhyolite.com

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