This is a known issue with Mozilla Firefox running on Ubuntu for amd64 systems. The correct solution is:

1.open Firefox and type “about:config” in address bar

2.create a new Boolean preference (right click on an empty space), name it “network.protocol-handler.expose.telnet” and set the value “false” and restart the browser. That should be enough for Firefox to let us select an external application to open “telnet://” links.

3. Then run this script:

   !/bin/sh

address=echo ${*##telnet://} | sed 's/:/ /g'

For xterm junkies :

xterm -e "telnet $address"

For gnome-terminal users :

uncomment the next line but comment

all other terminal launchers (xterm, konsole)

gnome-terminal -e "telnet $address"

For konsole hipsters :

konsole sends args separately to command so we use "" only for telnet

uncomment the next line but comment

all other terminal launchers (gnome-terminal, xterm)

konsole -e "telnet" $address

For furthur refrences : http://ccielab.ro/2009/11/telnet-handler-in-firefox-kubuntu/ http://www.tolaris.com/2010/08/23/enabling-telnet-and-ssh-urls-in-firefox-for-linux/

Regards.