{"id":160,"date":"2021-07-06T17:17:52","date_gmt":"2021-07-06T17:17:52","guid":{"rendered":"https:\/\/www.geekmungus.co.uk\/?p=160"},"modified":"2022-11-05T10:53:18","modified_gmt":"2022-11-05T10:53:18","slug":"putty-exe-couldnt-agree-a-key-exchange-algorithm","status":"publish","type":"post","link":"https:\/\/geekmungus.co.uk\/?p=160","title":{"rendered":"Putty.exe &#8211; &#8220;Couldn&#8217;t agree a key exchange algorithm&#8221;"},"content":{"rendered":"\n<p class=\"wp-block-paragraph\">I had this issue today, on a host that had recently had a software upgrade.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Problem:<\/strong> A host to which I was connecting with SSH gave this error: \u201cCouldn\u2019t agree a key exchange algorithm (available:\u00a0Curve25519-sha256@libssh.org, ECDH-sha2-nistp521, ECDH-sha2-nistp384, ECDH-sha2-nistp256)\u201d.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img decoding=\"async\" src=\"https:\/\/www.geekmungus.co.uk\/wp-content\/uploads\/2021\/07\/image.png\" alt=\"\" class=\"wp-image-161\"\/><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Solution:<\/strong> In my case I updated to a later release of Putty.exe and the issue was resolved. It appeared that the host was supporting ciphers that my putty.exe was not able to use, therefore the negotiation of a cipher failed.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>I had this issue today, on a host that had recently had a software upgrade. Problem: A host to which I was connecting with SSH gave this error: \u201cCouldn\u2019t agree a key exchange algorithm (available:\u00a0Curve25519-sha256@libssh.org, ECDH-sha2-nistp521, ECDH-sha2-nistp384, ECDH-sha2-nistp256)\u201d. Solution: In my case I updated to a later release of Putty.exe and the issue was resolved. &#8230; <a title=\"Putty.exe &#8211; &#8220;Couldn&#8217;t agree a key exchange algorithm&#8221;\" class=\"read-more\" href=\"https:\/\/geekmungus.co.uk\/?p=160\" aria-label=\"Read more about Putty.exe &#8211; &#8220;Couldn&#8217;t agree a key exchange algorithm&#8221;\">Read more<\/a><\/p>\n","protected":false},"author":4,"featured_media":137,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[20,22],"tags":[],"class_list":["post-160","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-random","category-security"],"_links":{"self":[{"href":"https:\/\/geekmungus.co.uk\/index.php?rest_route=\/wp\/v2\/posts\/160","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/geekmungus.co.uk\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/geekmungus.co.uk\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/geekmungus.co.uk\/index.php?rest_route=\/wp\/v2\/users\/4"}],"replies":[{"embeddable":true,"href":"https:\/\/geekmungus.co.uk\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=160"}],"version-history":[{"count":1,"href":"https:\/\/geekmungus.co.uk\/index.php?rest_route=\/wp\/v2\/posts\/160\/revisions"}],"predecessor-version":[{"id":1372,"href":"https:\/\/geekmungus.co.uk\/index.php?rest_route=\/wp\/v2\/posts\/160\/revisions\/1372"}],"wp:attachment":[{"href":"https:\/\/geekmungus.co.uk\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=160"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/geekmungus.co.uk\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=160"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/geekmungus.co.uk\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=160"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}