Set sv_register to 0. This will make sure that it doesn't show up on the internet tab.
You have probably not setup your router correctly. See http://portforward.com for help.
The configuration file syntax has changed. Try replaceing all the = with space, and read this documentation.
sv_name Teeworlds sample dm sv_map dm1 sv_scorelimit 20 sv_timelimit 10 sv_gametype dm sv_rcon_password remember sv_motd Teeworlds sample dm configuration sv_max_clients 12 sv_spectator_slots 10
sv_name Teeworlds sample tdm sv_map dm6 sv_scorelimit 50 sv_gametype tdm sv_rcon_password remember sv_motd Teeworlds sample tdm configuration
sv_name Teeworlds sample ctf sv_map ctf2 sv_scorelimit 400 sv_gametype ctf sv_rcon_password remember sv_motd Teeworlds sample ctf configuration
Syntax: setting value
This is the name of the server which will show up in the server browser. (default: unnamed server)
The map that is chosen when starting the server. (default: dm1)
Used to specify multiple maps which rotates after the time or score limit is reached. (default: )
Warmup time in seconds before the game starts. If it is set to 1 it will start immideatly. (default: 1)
What score that should be reached to end the game. Don't forget to set this to zero if you want a timebased limit. (default: 20)
The time in minutes before the game ends. (default: 0)
What gametype, could be dm, tdm or ctf. (default: dm)
The server's binding port. (default: 8303)
Set number of rounds. Map will be changed after last round ends. (default: 1)
Whether the server should register on the masterserver or not (if on, it will show up in the server list). (default: 1)
Password to access the remote control (rcon). (default: )
Message of the day, shows when joining the server and under the server info-tab. (default: )
Number of clients which can be on the server. This can't be changed without restart. (default: 12)
Number of all the slots that should be spectators. (default: 0)
The time in minutes after the teams are uneven to use auto balance. (default: 1)
Turning on/off spam filter. (default: 1)
Password to join the server. (default: )
If this is on, player automatically join spectators when entering a server. (default: 0)
If teammates will hurt each other or not. (default: 0)
If this is off ninja is disabled. (default: 1)
Address to bind to. (default: )
What port the server reports to the master servers in cases of firewall rename/redirection rules. (default: 0)
Doubles the snap rate, the game gets a bit more responsive but it requires more than doubled bandwidth. Only recommended for LAN-servers. (default: 0)
Syntax: kick id
Kicks the user with the specified id out of the server.
Syntax: status
Shows client stats and ids.
Syntax: restart value
Null the score and starting warmup timer (depends on the value).
If no value, then new round begins instantly.