{"id":260,"date":"2015-03-24T14:12:39","date_gmt":"2015-03-24T12:12:39","guid":{"rendered":"http:\/\/le-moulin-de-verre.com\/fieldnotes\/?p=260"},"modified":"2015-04-22T23:24:24","modified_gmt":"2015-04-22T21:24:24","slug":"tackle-x11-display-issue","status":"publish","type":"post","link":"https:\/\/le-moulin-de-verre.com\/fieldnotes\/?p=260","title":{"rendered":"Tackle X11 remote display issue"},"content":{"rendered":"<p>We attempt to export a X11 display of a server to a remote computer. However the display does not appear on the remote host.<br \/>\nWe need to identify where it fails.<\/p>\n<h2>Check the client firewall<\/h2>\n<p>Obvious&#8230; but so necessary&#8230;.<br \/>\n&#8211; Check (and temporary deactivate if possible) the firewall of the client.<\/p>\n<h2>Check that display is well exported on the server<\/h2>\n<p>Yes this is evident but has to be checked first&#8230;<\/p>\n<h2>Verify that the client is listening<\/h2>\n<ul>\n<li>Check on the client that MOBAXterm or Exceed or another X server is effectively listening to port 6000<\/li>\n<li>Use <code>netstat<\/code> command to see if something is listening on port <code>netstat \u2013ano<\/code><\/li>\n<\/ul>\n<h2>Traceroute from server to the client<\/h2>\n<p>This could show an intermediate firewall or netxork equipment that may filter the traffic<br \/>\n<code>traceroute -p 6000 target_ip<\/code><\/p>\n<h2>Test connectivity with Nmap X11 script<\/h2>\n<p>Nmap provides X11 testing scripts to ease debug.<br \/>\nI did some tests to compare script results with 2 known working machines on the same subnet (that work) and the real server->client setup.<br \/>\nResults show differences. In the second attempt, Nmap indicates that X11 traffic may be filtered and X11 session cannot be started.<\/p>\n<h3>Attempt connection between working LAN machines:<\/h3>\n<p><code>nmap -Pn -p6000 --script x11-access target_IP_address_that_works<\/code><\/p>\n<pre><code>Starting Nmap 5.51 ( http:\/\/nmap.org ) at 2015-02-19 16:37 CET\nNmap scan report for target_host_that_works (target_IP_address_that_works)\nHost is up (0.0011s latency).\nPORT     STATE SERVICE\n6000\/tcp open  X11\n|_x11-access: X server access is granted\n\nNmap done: 1 IP address (1 host up) scanned in 0.08 seconds\n<\/code><\/pre>\n<h3>Attempt connection to the real client computer<\/h3>\n<p><code>nmap -Pn -p6000 --script x11-access target_IP_address<\/code><\/p>\n<p>Note the <em>filtered X11<\/em> words in result. Chances are high that a firewall is blocking our destination port.<\/p>\n<pre><code>Starting Nmap 5.51 ( http:\/\/nmap.org ) at 2015-02-19 16:37 CET\nNmap scan report for target_computer.corp (target_IP_address)\nHost is up.\nPORT     STATE    SERVICE\n6000\/tcp filtered X11\n\nNmap done: 1 IP address (1 host up) scanned in 2.08 seconds\n<\/code><\/pre>\n<h2>Re-check the client firewall<\/h2>\n<p>Yes, yes, already said&#8230;. but the gap between theory and practice &#8230;.just redo it&#8230;.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>We attempt to export a X11 display of a server to a remote computer. However the display does not appear on the remote host. We need to identify where it fails. Check the client firewall Obvious&#8230; but so necessary&#8230;. &#8211; Check (and temporary deactivate if possible) the firewall of the client. Check that display is &hellip; <a href=\"https:\/\/le-moulin-de-verre.com\/fieldnotes\/?p=260\" class=\"more-link\">Continue reading<span class=\"screen-reader-text\"> &#8220;Tackle X11 remote display issue&#8221;<\/span><\/a><\/p>\n","protected":false},"author":2,"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_newsletter_tier_id":0,"jetpack_publicize_message":"","jetpack_is_tweetstorm":false,"jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","enabled":false}}},"categories":[1],"tags":[],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/p5WcEf-4c","_links":{"self":[{"href":"https:\/\/le-moulin-de-verre.com\/fieldnotes\/index.php?rest_route=\/wp\/v2\/posts\/260"}],"collection":[{"href":"https:\/\/le-moulin-de-verre.com\/fieldnotes\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/le-moulin-de-verre.com\/fieldnotes\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/le-moulin-de-verre.com\/fieldnotes\/index.php?rest_route=\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/le-moulin-de-verre.com\/fieldnotes\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=260"}],"version-history":[{"count":10,"href":"https:\/\/le-moulin-de-verre.com\/fieldnotes\/index.php?rest_route=\/wp\/v2\/posts\/260\/revisions"}],"predecessor-version":[{"id":282,"href":"https:\/\/le-moulin-de-verre.com\/fieldnotes\/index.php?rest_route=\/wp\/v2\/posts\/260\/revisions\/282"}],"wp:attachment":[{"href":"https:\/\/le-moulin-de-verre.com\/fieldnotes\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=260"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/le-moulin-de-verre.com\/fieldnotes\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=260"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/le-moulin-de-verre.com\/fieldnotes\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=260"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}