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Rod
Asked: 2010-08-24 13:13:52 +0800 CST

How to avoid sendmail relay domains spoofing

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I have a bunch of domains as relay domains at my sendmail config, i noticed that some dirty botnet is using dns spoof to be able to send emails using those relay domains.

How it works:

a domain zzz.xxx.tld resolves back to 127.0.0.1, when my server tries to resolve zzz.xxx.tld it falls back to 127.0.0.1 spoof!

Is there anyway to fix/avoid/block this? relaying only on specific server ips would be better?

Thanks.

domain-name-system sendmail spoofing

1 Answers

  1. Do you need to have a hosts entry pointing to 127.0.0.1? Perhaps you could point the hosts to your external IP instead and only allow relaying from localhost.

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