{"id":49,"date":"2016-12-19T23:12:36","date_gmt":"2016-12-19T22:12:36","guid":{"rendered":"http:\/\/netgab.net\/web\/?p=49"},"modified":"2016-12-23T14:36:14","modified_gmt":"2016-12-23T13:36:14","slug":"vmware-esxi-mysterious-mac-addresses","status":"publish","type":"post","link":"https:\/\/netgab.net\/web\/2016\/12\/19\/vmware-esxi-mysterious-mac-addresses\/","title":{"rendered":"VMWare ESXi and mysterious MAC addresses"},"content":{"rendered":"<p>Lately I&#8217;ve done a lot of lab testing with access switches and security features. To be more precise, I&#8217;ve done 802.1X testing on Cisco switches with the new IBNS 2.0 configuration style &#8211; but that&#8217;s another story.<br \/>\nDuring testing, bogus MAC addresses are sent in frames from the ESXi host to my switch, which interferes with some security features &#8230;<\/p>\n<p><!--more--><\/p>\n<p>So here&#8217;s a sample lab exhibit:<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-50 size-large\" src=\"http:\/\/netgab.net\/web\/wp-content\/uploads\/2016\/12\/20161219_vmware-1024x453.png\" alt=\"Lab-exhibit\" width=\"700\" height=\"310\" srcset=\"https:\/\/netgab.net\/web\/wp-content\/uploads\/2016\/12\/20161219_vmware-1024x453.png 1024w, https:\/\/netgab.net\/web\/wp-content\/uploads\/2016\/12\/20161219_vmware-300x133.png 300w, https:\/\/netgab.net\/web\/wp-content\/uploads\/2016\/12\/20161219_vmware-768x340.png 768w, https:\/\/netgab.net\/web\/wp-content\/uploads\/2016\/12\/20161219_vmware.png 1106w\" sizes=\"auto, (max-width: 700px) 100vw, 700px\" \/><\/p>\n<p>We have an access switch connected to an ESXi host with one active virtual machine. No 802.1Q VLAN tagging is in place. The goal is to test a single client connected to on a physical switch port. The client has the MAC 00:50:56:11:22:33.<\/p>\n<p>The switch port is configured as 802.1X authenticator in multi domain mode. So <strong>one<\/strong> MAC address in the configured data VLAN (switchport access vlan &#8230;) and <strong>one<\/strong> MAC address in the voice VLAN (switchport voice vlan &#8230;) is allowed.<\/p>\n<p>During testing, the switch port on the network switch raises a security violation and the switch port goes into error disable state (security-violation), because a new MAC address is seen on the switch port. The MAC addresses are in the range 00:00:00:00:00:01 &#8211; 00:00:00:00:00:04. This behavior is reproducable in case the network adapter in the VM guest operating system (Windows) is disabled and enabled again.<\/p>\n<p>This is very, very disruptive and annoying during testing. First of all I captured on the VM itself if these frames are generated by my guest operating system &#8211; fail &#8211; no success at all! So, after I had physical access to the lab, I configured a SPAN session on that access port and voila, I captured the bad frames, which are reverse ARP frames.<\/p>\n<p>These RARP frames doesn&#8217;t make any sense, because they contain only the bogus MACs mentioned above. After some &lt;insert-your-search-engine-here&gt;&#8217;ing for VMWare and RARP I stumbled upon this KB article:<\/p>\n<p><a href=\"https:\/\/kb.vmware.com\/selfservice\/microsites\/search.do?language=en_US&amp;cmd=displayKC&amp;externalId=1556\">https:\/\/kb.vmware.com\/selfservice\/microsites\/search.do?language=en_US&amp;cmd=displayKC&amp;externalId=1556<\/a><\/p>\n<p>The feature &#8220;<strong>Notify Switches<\/strong>&#8221; has something to do with the RARP behavior in ESXi. And this feature makes perfectly sense in a VMotion migration scenario or in case the ESXi host is connected redundantly. In case the VM moves to a new link the vSwitch updates the physical switch MAC address table using RARP.<\/p>\n<p>However, I have no idea why this bogus MAC in the RARP frames is generated and furthermore I don&#8217;t get the good idea behind this (except the fact that this provides the content for my first blog post of course).<\/p>\n<p>Long story short: If you&#8217;re in a lab testing environment along with security features as 802.1X, MAB or port-security and simulate you clients using VMWare, make sure to <strong>disable<\/strong> the &#8220;<strong>Notify Switches<\/strong>&#8221; setting in your vSwitch or port-group configuration in VMware.\u00a0 Please refer to my linked VMWare KB article to find that setting.<\/p>\n<p>However, if you are in a productive environment, the setting makes perfectly sense and should be enabled in case of link redundancy (no port-channels) or vMotion scenarios.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Lately I&#8217;ve done a lot of lab testing with access switches and security features. To be more precise, I&#8217;ve done 802.1X testing on Cisco switches with the new IBNS 2.0 configuration style &#8211; but that&#8217;s another story. During testing, bogus MAC addresses are sent in frames from the ESXi host [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":true,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[1],"tags":[7,8,6],"class_list":["post-49","post","type-post","status-publish","format-standard","hentry","category-uncategorized","tag-dot1x","tag-security","tag-vmware"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v27.3 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>VMWare ESXi and mysterious MAC addresses - NetGab - The daily networking madness<\/title>\n<meta name=\"description\" content=\"VMware ESXi vSwitch behavior to generate bogus RARP MACs, which influence switch security features as 802.1X or port security.\" \/>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/netgab.net\/web\/2016\/12\/19\/vmware-esxi-mysterious-mac-addresses\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"VMWare ESXi and mysterious MAC addresses - NetGab - The daily networking madness\" \/>\n<meta property=\"og:description\" content=\"VMware ESXi vSwitch behavior to generate bogus RARP MACs, which influence switch security features as 802.1X or port security.\" \/>\n<meta property=\"og:url\" content=\"https:\/\/netgab.net\/web\/2016\/12\/19\/vmware-esxi-mysterious-mac-addresses\/\" \/>\n<meta property=\"og:site_name\" content=\"NetGab - The daily networking madness\" \/>\n<meta property=\"article:published_time\" content=\"2016-12-19T22:12:36+00:00\" \/>\n<meta property=\"article:modified_time\" content=\"2016-12-23T13:36:14+00:00\" \/>\n<meta property=\"og:image\" content=\"http:\/\/netgab.net\/web\/wp-content\/uploads\/2016\/12\/20161219_vmware-1024x453.png\" \/>\n<meta name=\"author\" content=\"joe\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:label1\" content=\"Written by\" \/>\n\t<meta name=\"twitter:data1\" content=\"joe\" \/>\n\t<meta name=\"twitter:label2\" content=\"Est. reading time\" \/>\n\t<meta name=\"twitter:data2\" content=\"2 minutes\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\\\/\\\/schema.org\",\"@graph\":[{\"@type\":\"Article\",\"@id\":\"https:\\\/\\\/netgab.net\\\/web\\\/2016\\\/12\\\/19\\\/vmware-esxi-mysterious-mac-addresses\\\/#article\",\"isPartOf\":{\"@id\":\"https:\\\/\\\/netgab.net\\\/web\\\/2016\\\/12\\\/19\\\/vmware-esxi-mysterious-mac-addresses\\\/\"},\"author\":{\"name\":\"joe\",\"@id\":\"https:\\\/\\\/netgab.net\\\/web\\\/#\\\/schema\\\/person\\\/b3c8a779d0a772a9b047559d7bba4ccd\"},\"headline\":\"VMWare ESXi and mysterious MAC addresses\",\"datePublished\":\"2016-12-19T22:12:36+00:00\",\"dateModified\":\"2016-12-23T13:36:14+00:00\",\"mainEntityOfPage\":{\"@id\":\"https:\\\/\\\/netgab.net\\\/web\\\/2016\\\/12\\\/19\\\/vmware-esxi-mysterious-mac-addresses\\\/\"},\"wordCount\":506,\"commentCount\":0,\"image\":{\"@id\":\"https:\\\/\\\/netgab.net\\\/web\\\/2016\\\/12\\\/19\\\/vmware-esxi-mysterious-mac-addresses\\\/#primaryimage\"},\"thumbnailUrl\":\"http:\\\/\\\/netgab.net\\\/web\\\/wp-content\\\/uploads\\\/2016\\\/12\\\/20161219_vmware-1024x453.png\",\"keywords\":[\"dot1x\",\"security\",\"vmware\"],\"inLanguage\":\"en-US\",\"potentialAction\":[{\"@type\":\"CommentAction\",\"name\":\"Comment\",\"target\":[\"https:\\\/\\\/netgab.net\\\/web\\\/2016\\\/12\\\/19\\\/vmware-esxi-mysterious-mac-addresses\\\/#respond\"]}]},{\"@type\":\"WebPage\",\"@id\":\"https:\\\/\\\/netgab.net\\\/web\\\/2016\\\/12\\\/19\\\/vmware-esxi-mysterious-mac-addresses\\\/\",\"url\":\"https:\\\/\\\/netgab.net\\\/web\\\/2016\\\/12\\\/19\\\/vmware-esxi-mysterious-mac-addresses\\\/\",\"name\":\"VMWare ESXi and mysterious MAC addresses - NetGab - The daily networking madness\",\"isPartOf\":{\"@id\":\"https:\\\/\\\/netgab.net\\\/web\\\/#website\"},\"primaryImageOfPage\":{\"@id\":\"https:\\\/\\\/netgab.net\\\/web\\\/2016\\\/12\\\/19\\\/vmware-esxi-mysterious-mac-addresses\\\/#primaryimage\"},\"image\":{\"@id\":\"https:\\\/\\\/netgab.net\\\/web\\\/2016\\\/12\\\/19\\\/vmware-esxi-mysterious-mac-addresses\\\/#primaryimage\"},\"thumbnailUrl\":\"http:\\\/\\\/netgab.net\\\/web\\\/wp-content\\\/uploads\\\/2016\\\/12\\\/20161219_vmware-1024x453.png\",\"datePublished\":\"2016-12-19T22:12:36+00:00\",\"dateModified\":\"2016-12-23T13:36:14+00:00\",\"author\":{\"@id\":\"https:\\\/\\\/netgab.net\\\/web\\\/#\\\/schema\\\/person\\\/b3c8a779d0a772a9b047559d7bba4ccd\"},\"description\":\"VMware ESXi vSwitch behavior to generate bogus RARP MACs, which influence switch security features as 802.1X or port security.\",\"breadcrumb\":{\"@id\":\"https:\\\/\\\/netgab.net\\\/web\\\/2016\\\/12\\\/19\\\/vmware-esxi-mysterious-mac-addresses\\\/#breadcrumb\"},\"inLanguage\":\"en-US\",\"potentialAction\":[{\"@type\":\"ReadAction\",\"target\":[\"https:\\\/\\\/netgab.net\\\/web\\\/2016\\\/12\\\/19\\\/vmware-esxi-mysterious-mac-addresses\\\/\"]}]},{\"@type\":\"ImageObject\",\"inLanguage\":\"en-US\",\"@id\":\"https:\\\/\\\/netgab.net\\\/web\\\/2016\\\/12\\\/19\\\/vmware-esxi-mysterious-mac-addresses\\\/#primaryimage\",\"url\":\"http:\\\/\\\/netgab.net\\\/web\\\/wp-content\\\/uploads\\\/2016\\\/12\\\/20161219_vmware-1024x453.png\",\"contentUrl\":\"http:\\\/\\\/netgab.net\\\/web\\\/wp-content\\\/uploads\\\/2016\\\/12\\\/20161219_vmware-1024x453.png\"},{\"@type\":\"BreadcrumbList\",\"@id\":\"https:\\\/\\\/netgab.net\\\/web\\\/2016\\\/12\\\/19\\\/vmware-esxi-mysterious-mac-addresses\\\/#breadcrumb\",\"itemListElement\":[{\"@type\":\"ListItem\",\"position\":1,\"name\":\"Home\",\"item\":\"https:\\\/\\\/netgab.net\\\/web\\\/\"},{\"@type\":\"ListItem\",\"position\":2,\"name\":\"VMWare ESXi and mysterious MAC addresses\"}]},{\"@type\":\"WebSite\",\"@id\":\"https:\\\/\\\/netgab.net\\\/web\\\/#website\",\"url\":\"https:\\\/\\\/netgab.net\\\/web\\\/\",\"name\":\"NetGab - The daily networking madness\",\"description\":\"Networking at its best ... and worst\",\"potentialAction\":[{\"@type\":\"SearchAction\",\"target\":{\"@type\":\"EntryPoint\",\"urlTemplate\":\"https:\\\/\\\/netgab.net\\\/web\\\/?s={search_term_string}\"},\"query-input\":{\"@type\":\"PropertyValueSpecification\",\"valueRequired\":true,\"valueName\":\"search_term_string\"}}],\"inLanguage\":\"en-US\"},{\"@type\":\"Person\",\"@id\":\"https:\\\/\\\/netgab.net\\\/web\\\/#\\\/schema\\\/person\\\/b3c8a779d0a772a9b047559d7bba4ccd\",\"name\":\"joe\",\"image\":{\"@type\":\"ImageObject\",\"inLanguage\":\"en-US\",\"@id\":\"https:\\\/\\\/secure.gravatar.com\\\/avatar\\\/32b66c7321ea985e8c54f9975e87605df70ac5e4167a1e4153d91d72c67cf150?s=96&d=retro&r=g\",\"url\":\"https:\\\/\\\/secure.gravatar.com\\\/avatar\\\/32b66c7321ea985e8c54f9975e87605df70ac5e4167a1e4153d91d72c67cf150?s=96&d=retro&r=g\",\"contentUrl\":\"https:\\\/\\\/secure.gravatar.com\\\/avatar\\\/32b66c7321ea985e8c54f9975e87605df70ac5e4167a1e4153d91d72c67cf150?s=96&d=retro&r=g\",\"caption\":\"joe\"}}]}<\/script>\n<!-- \/ Yoast SEO plugin. -->","yoast_head_json":{"title":"VMWare ESXi and mysterious MAC addresses - NetGab - The daily networking madness","description":"VMware ESXi vSwitch behavior to generate bogus RARP MACs, which influence switch security features as 802.1X or port security.","robots":{"index":"index","follow":"follow","max-snippet":"max-snippet:-1","max-image-preview":"max-image-preview:large","max-video-preview":"max-video-preview:-1"},"canonical":"https:\/\/netgab.net\/web\/2016\/12\/19\/vmware-esxi-mysterious-mac-addresses\/","og_locale":"en_US","og_type":"article","og_title":"VMWare ESXi and mysterious MAC addresses - NetGab - The daily networking madness","og_description":"VMware ESXi vSwitch behavior to generate bogus RARP MACs, which influence switch security features as 802.1X or port security.","og_url":"https:\/\/netgab.net\/web\/2016\/12\/19\/vmware-esxi-mysterious-mac-addresses\/","og_site_name":"NetGab - The daily networking madness","article_published_time":"2016-12-19T22:12:36+00:00","article_modified_time":"2016-12-23T13:36:14+00:00","og_image":[{"url":"http:\/\/netgab.net\/web\/wp-content\/uploads\/2016\/12\/20161219_vmware-1024x453.png","type":"","width":"","height":""}],"author":"joe","twitter_card":"summary_large_image","twitter_misc":{"Written by":"joe","Est. reading time":"2 minutes"},"schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":"Article","@id":"https:\/\/netgab.net\/web\/2016\/12\/19\/vmware-esxi-mysterious-mac-addresses\/#article","isPartOf":{"@id":"https:\/\/netgab.net\/web\/2016\/12\/19\/vmware-esxi-mysterious-mac-addresses\/"},"author":{"name":"joe","@id":"https:\/\/netgab.net\/web\/#\/schema\/person\/b3c8a779d0a772a9b047559d7bba4ccd"},"headline":"VMWare ESXi and mysterious MAC addresses","datePublished":"2016-12-19T22:12:36+00:00","dateModified":"2016-12-23T13:36:14+00:00","mainEntityOfPage":{"@id":"https:\/\/netgab.net\/web\/2016\/12\/19\/vmware-esxi-mysterious-mac-addresses\/"},"wordCount":506,"commentCount":0,"image":{"@id":"https:\/\/netgab.net\/web\/2016\/12\/19\/vmware-esxi-mysterious-mac-addresses\/#primaryimage"},"thumbnailUrl":"http:\/\/netgab.net\/web\/wp-content\/uploads\/2016\/12\/20161219_vmware-1024x453.png","keywords":["dot1x","security","vmware"],"inLanguage":"en-US","potentialAction":[{"@type":"CommentAction","name":"Comment","target":["https:\/\/netgab.net\/web\/2016\/12\/19\/vmware-esxi-mysterious-mac-addresses\/#respond"]}]},{"@type":"WebPage","@id":"https:\/\/netgab.net\/web\/2016\/12\/19\/vmware-esxi-mysterious-mac-addresses\/","url":"https:\/\/netgab.net\/web\/2016\/12\/19\/vmware-esxi-mysterious-mac-addresses\/","name":"VMWare ESXi and mysterious MAC addresses - NetGab - The daily networking madness","isPartOf":{"@id":"https:\/\/netgab.net\/web\/#website"},"primaryImageOfPage":{"@id":"https:\/\/netgab.net\/web\/2016\/12\/19\/vmware-esxi-mysterious-mac-addresses\/#primaryimage"},"image":{"@id":"https:\/\/netgab.net\/web\/2016\/12\/19\/vmware-esxi-mysterious-mac-addresses\/#primaryimage"},"thumbnailUrl":"http:\/\/netgab.net\/web\/wp-content\/uploads\/2016\/12\/20161219_vmware-1024x453.png","datePublished":"2016-12-19T22:12:36+00:00","dateModified":"2016-12-23T13:36:14+00:00","author":{"@id":"https:\/\/netgab.net\/web\/#\/schema\/person\/b3c8a779d0a772a9b047559d7bba4ccd"},"description":"VMware ESXi vSwitch behavior to generate bogus RARP MACs, which influence switch security features as 802.1X or port security.","breadcrumb":{"@id":"https:\/\/netgab.net\/web\/2016\/12\/19\/vmware-esxi-mysterious-mac-addresses\/#breadcrumb"},"inLanguage":"en-US","potentialAction":[{"@type":"ReadAction","target":["https:\/\/netgab.net\/web\/2016\/12\/19\/vmware-esxi-mysterious-mac-addresses\/"]}]},{"@type":"ImageObject","inLanguage":"en-US","@id":"https:\/\/netgab.net\/web\/2016\/12\/19\/vmware-esxi-mysterious-mac-addresses\/#primaryimage","url":"http:\/\/netgab.net\/web\/wp-content\/uploads\/2016\/12\/20161219_vmware-1024x453.png","contentUrl":"http:\/\/netgab.net\/web\/wp-content\/uploads\/2016\/12\/20161219_vmware-1024x453.png"},{"@type":"BreadcrumbList","@id":"https:\/\/netgab.net\/web\/2016\/12\/19\/vmware-esxi-mysterious-mac-addresses\/#breadcrumb","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https:\/\/netgab.net\/web\/"},{"@type":"ListItem","position":2,"name":"VMWare ESXi and mysterious MAC addresses"}]},{"@type":"WebSite","@id":"https:\/\/netgab.net\/web\/#website","url":"https:\/\/netgab.net\/web\/","name":"NetGab - The daily networking madness","description":"Networking at its best ... and worst","potentialAction":[{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https:\/\/netgab.net\/web\/?s={search_term_string}"},"query-input":{"@type":"PropertyValueSpecification","valueRequired":true,"valueName":"search_term_string"}}],"inLanguage":"en-US"},{"@type":"Person","@id":"https:\/\/netgab.net\/web\/#\/schema\/person\/b3c8a779d0a772a9b047559d7bba4ccd","name":"joe","image":{"@type":"ImageObject","inLanguage":"en-US","@id":"https:\/\/secure.gravatar.com\/avatar\/32b66c7321ea985e8c54f9975e87605df70ac5e4167a1e4153d91d72c67cf150?s=96&d=retro&r=g","url":"https:\/\/secure.gravatar.com\/avatar\/32b66c7321ea985e8c54f9975e87605df70ac5e4167a1e4153d91d72c67cf150?s=96&d=retro&r=g","contentUrl":"https:\/\/secure.gravatar.com\/avatar\/32b66c7321ea985e8c54f9975e87605df70ac5e4167a1e4153d91d72c67cf150?s=96&d=retro&r=g","caption":"joe"}}]}},"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/p8dgKr-N","_links":{"self":[{"href":"https:\/\/netgab.net\/web\/wp-json\/wp\/v2\/posts\/49","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/netgab.net\/web\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/netgab.net\/web\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/netgab.net\/web\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/netgab.net\/web\/wp-json\/wp\/v2\/comments?post=49"}],"version-history":[{"count":6,"href":"https:\/\/netgab.net\/web\/wp-json\/wp\/v2\/posts\/49\/revisions"}],"predecessor-version":[{"id":81,"href":"https:\/\/netgab.net\/web\/wp-json\/wp\/v2\/posts\/49\/revisions\/81"}],"wp:attachment":[{"href":"https:\/\/netgab.net\/web\/wp-json\/wp\/v2\/media?parent=49"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/netgab.net\/web\/wp-json\/wp\/v2\/categories?post=49"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/netgab.net\/web\/wp-json\/wp\/v2\/tags?post=49"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}