{"id":63,"date":"2008-06-01T14:55:07","date_gmt":"2008-06-01T19:55:07","guid":{"rendered":"http:\/\/installingcats.com\/?p=63"},"modified":"2008-06-01T14:55:07","modified_gmt":"2008-06-01T19:55:07","slug":"debugging-mac-os-x-dns-tcpdump","status":"publish","type":"post","link":"https:\/\/installingcats.com\/2008\/06\/01\/debugging-mac-os-x-dns-tcpdump\/","title":{"rendered":"Debugging Mac OS X DNS – tcpdump"},"content":{"rendered":"

Need to debug a slow Internet connection in OS X<\/a>? Or simply have a desire to watch incoming and outgoing DNS (domain name service) queries in Leopard? Then tcpdump is your friend.<\/p>\n

Open a terminal window and use the following command:<\/p>\n

sudo tcpdump -i en1 -s 128 port 53<\/code><\/p>\n

-i Sets which interface to listen to. en1 for me is the AirPort wifi card. en0 would be the ethernet card.
\n-s sets the number of bytes to “sniff” or “snarf” per call that goes through this interface. 128 gives us a bit better coverage than the default 68 bytes. If you find that tcpdump requests are showing up simply as [|domain], that means that the request is longer than 68 bytes and is truncated. To prevent truncation, increase -s.
\nport 53 is simply the network port for DNS communcation<\/p>\n

Learn more about tcpdump at developer.apple.com<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

Need to debug a slow Internet connection in OS X? Or simply have a desire to watch incoming and outgoing DNS (domain name service) queries in Leopard? Then tcpdump is your friend. Open a terminal window and use the following command: sudo tcpdump -i en1 -s 128 port 53 -i Sets which interface to listen […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[2],"tags":[131,32,103,132],"_links":{"self":[{"href":"https:\/\/installingcats.com\/wp-json\/wp\/v2\/posts\/63"}],"collection":[{"href":"https:\/\/installingcats.com\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/installingcats.com\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/installingcats.com\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/installingcats.com\/wp-json\/wp\/v2\/comments?post=63"}],"version-history":[{"count":0,"href":"https:\/\/installingcats.com\/wp-json\/wp\/v2\/posts\/63\/revisions"}],"wp:attachment":[{"href":"https:\/\/installingcats.com\/wp-json\/wp\/v2\/media?parent=63"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/installingcats.com\/wp-json\/wp\/v2\/categories?post=63"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/installingcats.com\/wp-json\/wp\/v2\/tags?post=63"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}