To build this within the NDK the following things have to be done: - By default the strongSwan sources of the current Git tree are used. They have to be prepared first (see HACKING for a list of required tools): ./autogen.sh && ./configure && make && make distclean It is also possible to use the sources from a different directory (e.g. an extracted tarball) by setting strongswan_DIR in app/src/main/jni/Android.mk. - The OpenSSL or BoringSSL sources are expected in app/src/main/jni/openssl. Since the sources need to be changed to be built on Android (and especially in the NDK) we provide a modified mirror of the official Android repositories on git.strongswan.org.