I've seen intermittent failures of dlopen() when trying to run this example:  tcp-nsc-zoo

msg="liblinux2.6.18.so: cannot open shared object file: No such file or directory", file=../src/internet/model/nsc-tcp-l4-protocol.cc, line=144

despite nsc being in the usual place and liblinux2.6.18.so being there.

I looked into one such case today and found that if I set LD_LIBRARY_PATH to include ../nsc/linux-2.6.18, it would clear the error.

looking into src/internet/wscript, I found this:

    lib_to_check = 'liblinux2.6.26.so'

    found = False
    for path in ['.', 'lib', 'lib64', 'linux-2.6.26']:
        if os.path.exists(os.path.join(conf.env['WITH_NSC'], path, lib_to_check)):
            # append the NSC kernel dir to the module path so that this dir
            # will end up in the LD_LIBRARY_PATH, thus allowing the NSC NS-3
            # module to find the necessary NSC shared libraries.
            found = True
            conf.env.append_value('NS3_MODULE_PATH',
                                  os.path.abspath(os.path.join(conf.env['WITH_NSC'], path)))

and later in the build, LD_LIBRARY_PATH will get the paths in NS3_MODULE_PATH

My read of the above is that waf will append 

One brute force method is to extend the above to include also liblinux2.6.18.so, which I would recommend (over doing nothing) for the release.  However, I would rather recommend that the above code just be future-proofed to allow for different nsc directories in the future, so perhaps just append all subdirectories of ../nsc to NS3_MODULE_PATH.