Where do I type that command?" People ask that all the time when they read my early Guides to (mostly) Harmless Hacking. I wrote those guides back when the Internet was in its infancy and almost everyone in cyberspace used telnet. However, nowadays you might never even hear about telnet, much less use it, unless you are a hacker. So if you are still wondering about telnet, today is your lucky day.
What Is Telnet?
Telnet is a protocol that is most commonly used to log into a remote computer. It also is the single most powerful hacking tool on the planet. With just a telnet client program, you can:
send email
download source code from web sites
send unexpected input to webservers that can give you amazing and sometimes illegal results
give arbitrary input to many other services on Internet host computers
probe the services offered by servers, routers and even people's home computers.
How to Telnet
Don't know how to telnet? Click the easy telnet links at http://happyhacker.org/wargame/ and land in the middle of a real hacker wargame! This should work regardless of your computer operating system -- if you have an up to date browser, if your online service provider gives you a true Internet connection, and if your computer is able to telnet at all.
Did those links get you into a telnet session? Were you able to login to a remote computer? If yes, congratulations.
If not, how can you fix the problem? If no telnet program appeared on your monitor when you clicked these links, perhaps your browser is too ancient to allow telnet. Try installing the latest Netscape browser (http://www.netscape.com). Or, perhaps your operating system does not include a telnet program. In that case, install or reinstall Windows 95 or 98. If you own a Mac, get the superb Mac OS X or Linux PPC (http://www.linuxppc.com).
If a telnet program came up and failed to connect, possibly the computer you were trying to telnet into was down or just plain no longer in existence. Or, you may be using America Online (or a similar extremely poor online service). If so, your simplest solution may be to get a better online service provider. Determined to hack using AOL? See http://happyhacker.org/aol.shtml for some ways to make AOL give you a true Internet connection.
OK, so you've managed to telnet for the first time. Presumably you don't want to limit yourself to telnet links on web sites. How do you telnet anywhere you want to go?
If you have Linux or any other type of Unix (BSD, SCO, Solaris, Sun OS, Irix, Ultrix, etc.) telneting is easy. Just bring up "console" or "shell" (or whatever your GUI calls the command line interface). At the prompt type:
telnet
More on Telnet: the Number One Hacker Tool
Windows 2000 works pretty much like Unix. See Figure 1 for an example of a Win 2000 telnet login. Not shown on the screen was the command "telnet 10.0.0.10", which I gave at the Command (MS-DOS) prompt.
Figure 1: Telnet using Windows 2000
If you have Windows 95, 98 or NT, to telnet, bring up the MS-DOS prompt (Start --> Programs --> MS-DOS).
Click "connect" then "remote system…". In the host name box place the host name or IP address of the computer to which you wish to telnet. Leave the Port and Term Type boxes alone for now.
Here is a really important point. Every day people email me complaining that some computer won't let them telnet into it. They ask what they are doing wrong. They aren't doing anything wrong:
Maybe the computer they are trying to reach no longer exists.
Maybe the computer they are trying to reach doesn't allow telnet logins. For example, whois.internic.net no longer allows telnet logins on port 23 (the default port). Click here to learn how to telnet into whois.internic.net on the right port for that particular server.
Maybe a firewall is blocking them.
Or maybe they make a telnet connection and the remote computer asks for a user name and password they don't have. Then they email me asking for how to get a login name and password that will work.
Newbie note: The owners or administrators of any Internet host computer decide who gets user names and passwords. Believe it or not, about once a week someone emails me asking what user name and password their own online service provider has assigned them for a telnet login. That's why I'm telling people the obvious -- if you want to telnet into any computer, and you don't have a user name and password, you must ask the owner, administrator of tech support for that system for a user name and password. If they won't give that to you, they don't want you to have it!
You can go to jail warning: If you guess the user name and password, or use a computer breakin technique to get or create them, or if someone other than an owner or administrator or a legitimate user on that system gives you a user name and password, it is against the law to use them. Many computer criminals give out user names and passwords that they obtained illegally.
