和ping命令一样，加个参数-6 就可以了
# telnet -6 ipv6.google.com 443
Trying 2607:f8b0:4007:803::200e...
Connected to ipv6.google.com.
Escape character is '^]'.
^]
telnet> quit
Connection closed.
[root@zhzl ~]# telnet -6 ipv6.google.com 80
Trying 2607:f8b0:4007:80d::200e...
Connected to ipv6.google.com.
Escape character is '^]'.
^]
telnet> quit
Connection closed.