-ERROR: Missing parameter(s).
Usage: https://ipv4.tunnelbroker.net/ipv4_end.php?ip=IPV4ADDR&pass=MD5PASS&apikey=USERID&tid=TUNNELID
 -or-: https://USERNAME:PASSWORD@ipv4.tunnelbroker.net/ipv4_end.php?tid=TUNNELID (auto-detect IP)
       https://USERNAME:PASSWORD@ipv4.tunnelbroker.net/ipv4_end.php?tid=TUNNELID&ip=IPV4ADDR

IPV4ADDR: Your IPv4 endpoint.  Set to AUTO to determine your IP based on the IP you requested this page from.  Previously passed as ipv4b.
MD5PASS : The MD5 hash of your password.  You may be able to 'echo -n YOURPASSWORD | md5sum' to produce the MD5 hash of your password.
USERID  : The UserID shown on the main page of tunnelbroker.net when you log in.  Previously referred to as user_id.
TUNNELID: The ID of the tunnel you're updating the endpoint on.  This can be found on the tunnel information page.  Previously referred to as the Global Tunnel ID / tunnel_id.

The following parameters are only usable when accessing this script over https.
USERNAME: Your tunnelbroker.net username.
PASSWORD: Your tunnelbroker.net password.

The legacy parameter names will continue to work for the forseable future.  Naming of them changed to be more in line with industry convention and their roles.