{"id":6471,"date":"2017-02-11T15:43:17","date_gmt":"2017-02-11T07:43:17","guid":{"rendered":"http:\/\/rmohan.com\/?p=6471"},"modified":"2017-02-11T15:43:17","modified_gmt":"2017-02-11T07:43:17","slug":"reverse-mapping-checking-getaddrinfo-and-possible-break-in-attempt-error-messages-via-ssh","status":"publish","type":"post","link":"https:\/\/mohan.sg\/?p=6471","title":{"rendered":"reverse mapping checking getaddrinfo&#8221; and &#8220;POSSIBLE BREAK-IN ATTEMPT&#8221; error messages via SSH"},"content":{"rendered":"<section class=\"field_kcs_issue_txt\">\n<div class=\"code-raw\">\n<pre><code>$ ssh hostname\r\nreverse mapping checking getaddrinfo for client.example.com [10.0.0.1] failed - POSSIBLE BREAK-IN ATTEMPT!\r\nusername@hostname password: \r\n<\/code><\/pre>\n<\/div>\n<\/section>\n<section class=\"field_kcs_resolution_txt\">\n<h2>Resolution<\/h2>\n<p>There are several ways to resolve this issue:<\/p>\n<ul>\n<li>Setup a <a href=\"https:\/\/access.redhat.com\/site\/documentation\/en-US\/Red_Hat_Enterprise_Linux\/5\/html\/Deployment_Guide\/s2-bind-configuration-zone-reverse.html\">Reverse DNS Record (aka PTR Record)<\/a> for the SSH client.<\/li>\n<li>Ensure <code>UseDNS no<\/code> and <code>GSSAPIAuthentication no<\/code> are set in <code>\/etc\/ssh\/sshd_config<\/code> on the SSH server, then restart the sshd.<\/li>\n<li>Confirm that <code>\/etc\/hosts<\/code> on the SSH server has an entry for the SSH client IP address and hostname.<\/li>\n<\/ul>\n<\/section>\n","protected":false},"excerpt":{"rendered":"<p> $ ssh hostname reverse mapping checking getaddrinfo for client.example.com [10.0.0.1] failed &#8211; POSSIBLE BREAK-IN ATTEMPT! username@hostname password: Resolution <\/p>\n<p>There are several ways to resolve this issue:<\/p>\n<p> Setup a Reverse DNS Record (aka PTR Record) for the SSH client. Ensure UseDNS no and GSSAPIAuthentication no are set in \/etc\/ssh\/sshd_config on the SSH server, then restart [&#8230;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[5,73],"tags":[],"_links":{"self":[{"href":"https:\/\/mohan.sg\/index.php?rest_route=\/wp\/v2\/posts\/6471"}],"collection":[{"href":"https:\/\/mohan.sg\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/mohan.sg\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/mohan.sg\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/mohan.sg\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=6471"}],"version-history":[{"count":1,"href":"https:\/\/mohan.sg\/index.php?rest_route=\/wp\/v2\/posts\/6471\/revisions"}],"predecessor-version":[{"id":6472,"href":"https:\/\/mohan.sg\/index.php?rest_route=\/wp\/v2\/posts\/6471\/revisions\/6472"}],"wp:attachment":[{"href":"https:\/\/mohan.sg\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=6471"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/mohan.sg\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=6471"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/mohan.sg\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=6471"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}