An update to the ns-3.18 release, numbered ns-3.18.1, has now been posted at

ns-3.18.1 adds support for the Clang/LLVM compiler used in Apple Xcode 5.0.1, released with OS X Mavericks, and also in FreeBSD and other distributions. ns-3.18.1 also provides Python API scanning support for recent compilers, and updates support (via the bake build system) for Direct Code Execution version 1.1, released in September 2013.

The next feature release, ns-3.19, is scheduled for mid-December.