i can not use telnet via dude ,but i can use telnet with putty ,cmd, SucureCRT.
please give any suggestion in advance.
If you are running your Dude on Windows 7 then that will be the problem. Telnet is not installed on Windows 7 by default but can be added as a feature. Even when you add Telnet as a feature it still not able to be launched by The Dude. This may be because Telnet is no longer in the directory where The Dude expects to find it. Either make a new tool that calls telnet from wherever Microsoft have decided to hide it, or keep using Putty.