{"id":2970,"date":"2024-11-14T13:44:10","date_gmt":"2024-11-14T12:44:10","guid":{"rendered":"https:\/\/www.robert-oswald.de\/blog\/?p=2970"},"modified":"2025-03-30T13:46:00","modified_gmt":"2025-03-30T12:46:00","slug":"disable-duplicate-address-detection-in-networkmanager-connections","status":"publish","type":"post","link":"https:\/\/www.robert-oswald.de\/blog\/?p=2970","title":{"rendered":"Disable Duplicate Address Detection in NetworkManager Connections"},"content":{"rendered":"\n<h3 class=\"wp-block-heading\" id=\"ipv4-duplicate-address-detection\">IPv4 Duplicate Address Detection<\/h3>\n\n\n\n<p>It appears that IPv4 DAD is enabled in NetworkManager connections now by default.<br><a href=\"https:\/\/gitlab.freedesktop.org\/NetworkManager\/NetworkManager\/-\/blob\/0e64af01cc520ac3e44a815d7050a65e8816496a\/NEWS#L77\" target=\"_blank\" rel=\"noreferrer noopener\">NetworkManager Changelog<\/a><\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"what-could-be-a-problem-with-that\">What Could be a Problem With That?<\/h3>\n\n\n\n<p>In a situation where you want the same IP address on multiple interfaces at the same time the second interface is prevent to go online as long as the first interface has already assigned the desired IP address. A real life example for that circumstance is when you want a fixed IP address on your laptop and your network connection should switch seamlessly between Wi-Fi and Ethernet.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"sharing-ip-over-wi-fi-and-ethernet\">Sharing IP over Wi-Fi and Ethernet<\/h3>\n\n\n\n<p>By default the metric for wired connections is lower than for Wi-Fi connections so that wired connections are priorized in the routing table.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"disable-dad-for-dedicated-connections\">Disable DAD for Dedicated Connections<\/h3>\n\n\n\n<p>Unfortunately this option is at the time writing this article not available in the NetworkManager GUI so we need to use the <code>nmcli<\/code> command.<\/p>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"show-configured-connections\">Show Configured Connections<\/h4>\n\n\n\n<pre class=\"wp-block-code\"><code>user@host:~$ nmcli connection show \nNAME                     UUID                                  TYPE      DEVICE          \nwifi                     27328bfa-cd5b-4bde-965f-24d46f7078df  wifi      wlo1            \nWired connection 1       74f9dedd-6ea2-3882-8c62-162d637f39b9  ethernet  enx030ec4e054c6 \nlo                       0b43a56d-ca15-4fe2-b0e7-36s5eea7c311  loopback  lo              \n<\/code><\/pre>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"disable-dad-for-wi-fi-and-ethernet-connection\">Disable DAD for Wi-Fi and Ethernet Connection<\/h4>\n\n\n\n<pre class=\"wp-block-code\"><code>user@host:~$ nmcli connection show wifi | grep dad\nipv4.dad-timeout:                       -1 (default)\nuser@host:~$ nmcli connection modify wifi ipv4.dad-timeout 0\nuser@host:~$ nmcli connection show wifi | grep dad\nipv4.dad-timeout:                       0 (off)\n\nuser@host:~$ nmcli connection show Wired\\ connection\\ 1 | grep dad\nipv4.dad-timeout:                       -1 (default)\nuser@host:~$ nmcli connection modify Wired\\ connection\\ 1 ipv4.dad-timeout 0\nuser@host:~$ nmcli connection show Wired\\ connection\\ 1 | grep dad\nipv4.dad-timeout:                       0 (off)\n<\/code><\/pre>\n\n\n\n<p>These changes are persistent and you can find them in the connection files after the commands have been applied. Be aware that since Ubuntu 24.04 these files are located in <code>\/etc\/netplan<\/code>.  <\/p>\n\n\n\n<p>The modified connections have to be re-connected to take changes in affect.  <\/p>\n\n\n\n<p><a href=\"https:\/\/blog.riton.fr\/en-us\/2024\/04\/how-ive-migrated-from-xubuntu-22.04-lts-to-24.04-lts\/\" target=\"_blank\" rel=\"noreferrer noopener\">Based on this article<\/a><\/p>\n\n\n\n<p><\/p>\n","protected":false},"excerpt":{"rendered":"<p>IPv4 Duplicate Address Detection It appears that IPv4 DAD is enabled in NetworkManager connections now by default.NetworkManager Changelog What Could be a Problem With That? In a situation where you want the same IP address on multiple interfaces at the same time the second interface is prevent to go online as long as the first [&hellip;]<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_import_markdown_pro_load_document_selector":0,"_import_markdown_pro_submit_text_textarea":"","ngg_post_thumbnail":0,"footnotes":""},"categories":[5],"tags":[],"class_list":["post-2970","post","type-post","status-publish","format-standard","hentry","category-linux"],"_links":{"self":[{"href":"https:\/\/www.robert-oswald.de\/blog\/index.php?rest_route=\/wp\/v2\/posts\/2970","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.robert-oswald.de\/blog\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.robert-oswald.de\/blog\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.robert-oswald.de\/blog\/index.php?rest_route=\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.robert-oswald.de\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=2970"}],"version-history":[{"count":5,"href":"https:\/\/www.robert-oswald.de\/blog\/index.php?rest_route=\/wp\/v2\/posts\/2970\/revisions"}],"predecessor-version":[{"id":3052,"href":"https:\/\/www.robert-oswald.de\/blog\/index.php?rest_route=\/wp\/v2\/posts\/2970\/revisions\/3052"}],"wp:attachment":[{"href":"https:\/\/www.robert-oswald.de\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=2970"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.robert-oswald.de\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=2970"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.robert-oswald.de\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=2970"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}