ns-3 (replacement for ns-2) is one standalone program, ns-3.0.12.tar.gz from
The code for the framework and the default models provided
by ns-3 is built as a set of libraries. User simulations
are expected to be written as simple programs that make
use of these ns-3 libraries.
Unpack to /home/"user" and build with command
'./waf configure --enable-gcov' and './waf'
and then just follow doc/build.txt
(Forgot: no "dependencies", all you need is python and g++)
Also consider: ns-allinone-2.32 (ns-2)