dcc not working

Vernon Schryver vjs@calcite.rhyolite.com
Fri Jun 1 16:23:34 UTC 2007

> From: "Robert Welz" 

> > I can't get dcc working. My email traffic is at about 3500 email/day so I

> > What is the IP address of your DCC client?  I get NXDOMAIN when trying
> > to resolve the name Nausciaa.fixe-post.de from your tcpdump output.

> Outside my firewalls ethereal shows me an
> 37426 6277 DCCP Request: No-Op is an RFC 1918 IP address that is useless on the
Internet.  No DCC server can answer a request from
I assume you are using a NAT box of some sort such as a so called
"broadband gateway" to translate between and some
other IP address such as

Is your NAT box configured to translate the addresses in the 
IP headers of UDP packets including DCC requests?  Some NAT implementations
do such things under the heading "PAT".
If that is not possible, can you configure the NAT box to put your
DCC client to be in a "DMZ"?

Again, port 6277 should be handled by your firewalls and NAT box like
port 53.

Your mail uses an SMTP HELO value of www.fixe-post.de from an IP address
of  The IP address of www.fixe-post.de is also, but nothing answers port 80 at
If there should be web pages at http://www.fixe-post.de it might be
easiest to debug your NAT configuration for ports 80 and 443 before
considering port 6277.

> What does No-Op mean, except No-Operational?

NOP has meant "no operation" or "do nothing" for almost forever.  See

The NOP request in the DCC client-server protocol does nothing
significant.  It is used by DCC clients to find the fastest available
DCC server among the IP addresses of servers in the /var/dcc/map file.

Vernon Schryver    vjs@rhyolite.com

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