Here is .pro format for NS3 integration(for anyone else in future):
TEMPLATE = app
CONFIG += console c++11
CONFIG -= app_bundle
CONFIG -= qt
NS_BUILD_DIR = <path-to-ns3>/ns-3.26/build
LIBS += -L$$NS_BUILD_DIR
INCLUDEPATH += $$NS_BUILD_DIR
unix {
SHARED_LIB_FILES = $$files($$NS_BUILD_DIR/*.so)
for(FILE, SHARED_LIB_FILES) {
BASENAME = $$basename(FILE)
CLEARNAME = $$replace(BASENAME,libns,ns)
CLEARNAME = $$replace(CLEARNAME,.so,)
LIBS += -l$$CLEARNAME
}
}
SOURCES += main.cpp