MailCleaner Slave DNS and other Network Adjustments

Posted at 11:37:59 PM in Spam Management Gateways (6) | Read count: 4721

One of the things I discovered, or re-discovered, while setting up MailCleaner is DNS lookups will not work with public name servers. While running the mailscanner spam test (located here /usr/mailcleaner/bin/ 

 /usr/mailcleaner/bin/ -D check.eml > results

I received a notice that my rbls were blocked and to contact the administrator. Researching a little, I found this:

Anthony Cartmell-2 wrote
> The caching aspect isn't particularly relevant.

> The problem is that your ISP's name server will be querying the URIBL
> server on behalf of perhaps thousands of SpamAssassin instances on other
> machines. So it's blocked because it's making too many queries from a
> single IP address.

Yep, thank you, already figured this out. My problem was that I was not sure
how exactly DNS works, and by studying dnsmasq configuration I incorrectly
assumed that a dns server is always supposed to have an upstream server.
Apparently this is the case for dnsmasq but not the case in general. So now
with djbdns setup that I have in place that perform recursive queries
starting from the root servers this all makes sense. Thank you again.

The master MailCleaner server was easy to fix. The web interface has a connection to upate the DNS information under Base System. the slave server was not so easy to fix. When I try to connect to the web browser at the slave, I get redirected to the web site on the main server. Digging around, I found in /usr/mailcleaner/scripts/configuration. Running it ask questions about the network interface, which includes the DNS settings. After running that and answering the questions, I ran dig to see what DNS server the slave would check. The end of the script errored out as it did not restart the network interface, but it did set the DNS servers.

This made the most dramatic change in spam detection for me. I pretty much had SpamAssassin configured, but with the DNS being blocked, many of the SpamAssassin tests didn't work either.

Written by Leonard Rogers on Saturday, February 7, 2015 | Comments (0)

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