Telnet and netstat

edit: I am putting tis edit at the top, in case it is your answer. The ':telnet' may mean that the is an active open telnet port on your system. It is listening. Otherwise, you should get further info regarding an actual connection (what other IP address is trying to make a connection to you, or if is already established.
end edit.

DOS/Windows command?
GNU/Linux utility?
The AnalogX Windows utility?
It may make a difference.
Are you on a network, just connected to the Internet?

I don't use these things a lot, but I may have a few hints. Telnet is a protocol used to send commands to a system across a network, but protocols like HTTP are much more frequently used these days. This may be indicating that someone is trying to telnet into your machine, or maybe it is just indicating that a port is available for telnet (usually TCP port 23, but not necessarily).

You aren't on a mainframe, are you? Even on a LAN, SysAdmins may use this for debugging and stuff. I suppose it is possible that someone is trying to have a peek at you. Or crack your system.

Anyway, can you post a little more of your particulars (OS, what kind of network, which netstat you are using) and maybe a little of the output from netstat (hide actual IP addresses) and what parameters you are calling netstat with, if any.

I am going to quit while I still know (maybe) what I am talking about. There are quite a few people here that could probably give you an answer in two seconds flat, given a little more info.