Telnet?

Telnet is essentially a terminal emulator which allows users to access a remote computer with a valid shell. The default port for telnet is port 23. To control your computer, you have to set up a telnet server, which is accessed by a telnet client. Network administrators use these for remote access and control to machines: but hackers also try to use them. Using telnet is like using the computer as if you were sitting infront of it at a prompt. One thing that should be noted, however, is that telnet works in plaintext, meaning none of the data sent across the wire is encrypted -- which is very dangerous when you are sending your passwords.

You should check out this for more detail.

Wiki on Telnet has tons of information about it.

As Visage said, Telnet sends data in plain text, and this is very dangerous even in your LAN.
A few years ago I was working for a web hosting/design company, and we had like 5 computers in our LAN. We used to use Telnet a lot in our LAN because we figured this is secure, since all the computers in the LAN were trusted. However, after someone placed a root kit in one of the computers and a packet sniffer, we found out how much this sucked, because that guy had access to all our passwords. So since that day we used only SSH.

Use SSH. Infact, most linux distros have ssh running as a server process all the time.

If hackers can telnet me, how can i stop this? will my firewall handle this?

As mentioned before, using telnet isn't too safe. What I would recommend is either using SSH, or setting up a firewall to only accept telnet connections from protected IPs...but even then you are vulnerable to packet sniffing and man in the middle attacks.

Go with SSH.

To prevent others from telnetting you, just turn off your telnet server!

Quote:

Original post by isiahil If hackers can telnet me, how can i stop this? will my firewall handle this?

you can block the port with a firewall, you can disable the service or configure it to allow only certain ranges of ip's to log in.

The better advice is to disable everything you don't need/you don't know what it is.

Me and my friend are tryin to telnet each other right now and it dosent work. i open up command prompt and type "telnet" and then type "open" and input his ip, but it says it failed to connect. I know yall are suggesting other things we are doing this to get ahead of the class and the next subject is telnet so we are tryin to learn it. :) (even though that sounds nerdy)

Quote:

Original post by isiahil Me and my friend are tryin to telnet each other right now and it dosent work. i open up command prompt and type "telnet" and then type "open" and input his ip, but it says it failed to connect. I know yall are suggesting other things we are doing this to get ahead of the class and the next subject is telnet so we are tryin to learn it. :) (even though that sounds nerdy)

Are you using windows?

1) Click START and choose Run.
2) Type "telnet www.gamedev.net 80" in the box and click OK.
3) In the TELNET window type "GET http://www.gamedev.net/community/forums/topic.asp?topic_id=292729" and press ENTER

The program should return this thread as a web browser would see it (the HTML).

Many systems and hardware devices have a Telnet interface to configure them. I configured a laser printer recently through Telnet. I use it heavily to troubleshoot PCs in a WAN environment.

Telnet is great!

When i type that into run it gives me a command prompt type window, but when i type in it no characters so up for some strange reason, its just like pressing the space bar because all the comes up when i press a key is blank spaces. I have windows XP. We both disabled our firewalls.

Quote:

Original post by isiahil When i type that into run it gives me a command prompt type window, but when i type in it no characters so up for some strange reason, its just like pressing the space bar because all the comes up when i press a key is blank spaces. I have windows XP. We both disabled our firewalls.

I don't think windows keeps the telnet port open and any service running for it. That is usually a unix/linux service.

But if you connect to another server using telnet, it isn't safe because it uses plain text even for passwords, so someone can sniff your packets (as previously said).

Quote:

Original post by isiahil When i type that into run it gives me a command prompt type window, but when i type in it no characters so up for some strange reason, its just like pressing the space bar because all the comes up when i press a key is blank spaces. I have windows XP. We both disabled our firewalls.

Yeah, Microsoft's Telnet client sucks. If you run telnet itself without connecting to anything and type in the command "set localecho" before connecting it will allow you to see what you type. It overwrites characters already the screen though [headshake]

You're probably better off downloading a free telnet client.

BTW: The above should still work even though you can't see what your typing (when you press ENTER) -- the data is there! The problem is if you make a typo [smile]

Well, if you write a special program as the control program that listens on a port, you can telnet to that and send text over and have your control program process it. Then you can emulate keyboard and mouse commands, or open and close programs, or send over files.. but that's just the noobish approach.