Installation Steps:
i) Open a terminal, type sudo apt-get install build-essential autoconf automake libxmu-dev
ii) Download the ns-allinone-2.35.tar.gz file here.
iii) Extract the file and goto ns-allinone-2.35 folder
iv) In terminal, type ./install
v) At the end of ./install, you will be asked to set path. Copy the Path information in local file.
After ns2 installation you have to set path. For that
i) Goto the ns2 folder (or) The folder where you have ns-allinone-2.35
ii) gedit .bashrc
export PATH=$PATH:<path1>:<path2>:<path3>
export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:<path1>:<path2>
export TCL_LIBRARY=$TCL_LIBRARY:<path>
For e.g) .bashrc file ( http://ubuntuone.com/4TzcPf6PLfihJbogRmyxsO )
iii) source .bashrc
iv) Ensure that you installed ns2 correctly by enabling the hello packets (or) put some print statement inside the forward() function and seeing those in terminal after running the tcl file.