次のコマンドがFacebook Webサイトのデータパケットをキャプチャできないのはなぜですか？
sudo tcpdump host facebook.com and dst port 443
しかし、次の争奪戦
sudo tcpdump host java.com
答え1
https://facebook.comリダイレクトhttps://www.facebook.comIPアドレスはfacebook.comとは異なります。 ssl.facebook.comもありますが、それが何であるかよくわかりません。
$ host facebook.com
facebook.com has address 69.171.229.11
facebook.com has address 69.171.224.37
facebook.com has address 66.220.158.11
facebook.com has address 66.220.149.11
facebook.com has address 69.171.242.11
facebook.com has IPv6 address 2a03:2880:10:1f02:face:b00c:0:25
facebook.com has IPv6 address 2a03:2880:2110:3f01:face:b00c::
facebook.com has IPv6 address 2a03:2880:10:8f01:face:b00c:0:25
facebook.com mail is handled by 10 smtpin.mx.facebook.com.
$ host www.facebook.com
www.facebook.com has address 69.171.237.16
www.facebook.com has IPv6 address 2a03:2880:10:1f03:face:b00c:0:25
$ host ssl.facebook.com
ssl.facebook.com is an alias for star.facebook.com.
star.facebook.com has address 69.171.234.39
star.facebook.com has IPv6 address 2a03:2880:10:cf02:face:b00c:0:4
一方、java.comの場合、www.java.comとjava.comのエントリは同じです。
$ host java.com
java.com has address 137.254.16.66
java.com mail is handled by 10 mx5.sun.com.
java.com mail is handled by 10 mx6.sun.com.
java.com mail is handled by 10 mx8.sun.com.
java.com mail is handled by 10 mx9.sun.com.
$ host www.java.com
www.java.com is an alias for java.com.
java.com has address 137.254.16.66
java.com mail is handled by 10 mx5.sun.com.
java.com mail is handled by 10 mx6.sun.com.
java.com mail is handled by 10 mx8.sun.com.
java.com mail is handled by 10 mx9.sun.com.