Crostini の IP アドレスを調べる
$ ip addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
5: eth0@if6: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
    link/ether 00:16:3e:f8:6e:b1 brd ff:ff:ff:ff:ff:ff link-netnsid 0
    inet 100.115.92.199/28 brd 100.115.92.207 scope global eth0
       valid_lft forever preferred_lft forever
    inet6 fe80::216:3eff:fef8:6eb1/64 scope link 
       valid_lft forever preferred_lft forever
→ http://100.115.92.207:8080 で netbeans で立ち上げた Web サーバにアクセス可能