Not much used anymore. But nice to use on an old Mac!
On a old Mac use NSCA telnet.
What could you do with it? Well.. this:
Many people use sites like http://www.whatismyip.com or http://www.ipchicken.com to identify the public IP address of an unfamiliar network.
Telnet to ip.blindhog.net or 188.8.131.52 if you do not have a web browser (router, switch, linux).
Note: the original domain name was v4address.com but it has not worked for a while.
[josh@webserver ~]$ telnet ip.blindhog.net
Connected to ip.blindhog.net.
Escape character is ‘^]’.
This is the telnet autoresponder at v6address.com.
You have connected over IPv4.
Your IP address is 184.108.40.206
Connection closed by foreign host.