{"id":56,"date":"2016-10-18T07:22:56","date_gmt":"2016-10-18T14:22:56","guid":{"rendered":"http:\/\/wp.estone.ca\/?p=56"},"modified":"2019-03-18T13:26:12","modified_gmt":"2019-03-18T20:26:12","slug":"3","status":"publish","type":"post","link":"https:\/\/www.estone.ca\/?p=56","title":{"rendered":"Prevent spam with DNS"},"content":{"rendered":"<p>I learned a neat antispam technique\u00a0from a good colleague of mine on how to help stop spam email coming into your mail host. The goal is to\u00a0trick spamming mail servers to hit a fake mail server, thus causing them to give up and not attempt a 2nd connection to your true mail server. The technique to accomplish this is to configure your MX records in DNS and rank your &#8220;true&#8221; mail server lower than your fake one.\u00a0 <img loading=\"lazy\" decoding=\"async\" class=\"alignnone\" title=\"devil\" src=\"https:\/\/cdn.ckeditor.com\/4.4.0\/full-all\/plugins\/smiley\/images\/devil_smile.png\" alt=\"devil\" width=\"23\" height=\"23\" data-cke-saved-src=\"\/\/cdn.ckeditor.com\/4.4.0\/full-all\/plugins\/smiley\/images\/devil_smile.png\" \/><\/p>\n<p>Here&#8217;s my example below using bind in Linux.<\/p>\n<div><em>;<br \/>\n$TTL\u00a0\u00a0\u00a0 1D<br \/>\n@\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 IN\u00a0\u00a0\u00a0\u00a0\u00a0 SOA\u00a0\u00a0\u00a0\u00a0 ns1.estone.ca. hostmaster.estone.ca. (<br \/>\n2015032701\u00a0\u00a0\u00a0\u00a0\u00a0 ; Serial<br \/>\n7200\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 ; Refresh<br \/>\n7200\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 ; Retry<br \/>\n2419200\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 ; Expire<br \/>\n10800 )\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 ; Negative Cache TTL<br \/>\n;<br \/>\nNS\u00a0\u00a0\u00a0\u00a0\u00a0 ns1<br \/>\nNS\u00a0\u00a0\u00a0\u00a0\u00a0 ns2<br \/>\nMX\u00a0\u00a0\u00a0\u00a0\u00a0 10 mail1<br \/>\nMX\u00a0\u00a0\u00a0\u00a0\u00a0 20 mail<br \/>\n;<\/em><\/div>\n<div><\/div>\n<div><em>;<br \/>\nestone.ca.\u00a0\u00a0\u00a0\u00a0\u00a0 IN\u00a0\u00a0\u00a0\u00a0\u00a0 TXT\u00a0\u00a0\u00a0\u00a0 &#8220;v=spf1 mx -all&#8221;<\/em><\/div>\n<div><\/div>\n<div><em>mail\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 A\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 206.116.5.55<br \/>\nestone.ca.\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 A\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 206.116.5.55<br \/>\nns\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 A\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 206.116.5.55<br \/>\nns1\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 A\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 206.116.5.55<br \/>\nns2\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 A\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 206.116.5.111<br \/>\nwww\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 A\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 206.116.5.55<br \/>\ncomm\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 A\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 206.116.5.55<br \/>\nmail1\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 A\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 206.116.5.1<\/em>\u200bHere is the result of a host command:<\/p>\n<p>root@estone:~# host estone.ca<br \/>\nestone.ca has address 206.116.5.55<br \/>\n<em>estone.ca mail is handled by 10 mail1.estone.ca.<br \/>\nestone.ca mail is handled by 20 mail.estone.ca.<br \/>\nroot@estone:~#<\/em><\/p>\n<p>Now hopefully when a spam engine mail server attempts to connect to my fake mail1 email server, it will of course fail(because their is no mail service on the mail1 host) and then hopefully give up.<\/p>\n<\/div>\n","protected":false},"excerpt":{"rendered":"<p>I learned a neat antispam technique\u00a0from a good colleague of mine on how to help stop spam email coming into your mail host. The goal is to\u00a0trick spamming mail servers to hit a fake mail server, thus causing them to give up and not attempt a 2nd connection to your true mail server. The technique &hellip; <\/p>\n<p class=\"read-more\"><a class=\"btn btn-default\" href=\"https:\/\/www.estone.ca\/?p=56\"> Read More<span class=\"screen-reader-text\">  Read More<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":false,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2}},"categories":[1],"tags":[],"class_list":["post-56","post","type-post","status-publish","format-standard","hentry","category-mikesposts"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/sal9Cn-3","_links":{"self":[{"href":"https:\/\/www.estone.ca\/index.php?rest_route=\/wp\/v2\/posts\/56","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.estone.ca\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.estone.ca\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.estone.ca\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.estone.ca\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=56"}],"version-history":[{"count":4,"href":"https:\/\/www.estone.ca\/index.php?rest_route=\/wp\/v2\/posts\/56\/revisions"}],"predecessor-version":[{"id":224,"href":"https:\/\/www.estone.ca\/index.php?rest_route=\/wp\/v2\/posts\/56\/revisions\/224"}],"wp:attachment":[{"href":"https:\/\/www.estone.ca\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=56"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.estone.ca\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=56"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.estone.ca\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=56"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}