There are problems with how the ntop ebuilds (both 3.0 and 3.1) activate use flag dependant features in the src_compile function: ntop-3.0.ebuild: use readline || myconf="${myconf} --without-readline" use tcpd || myconf="${myconf} --with-tcpwrap" use ssl || myconf="${myconf} --without-ssl" ntop-3.1.ebuild: use readline || myconf="${myconf} --without-readline" use tcpd || myconf="${myconf} --with-tcpwrap" ...these should say && not || to actually to what is expected.
Oops, only the tcpd lines are wrong, the rest are correct, didn't notice the withouts on the other lines.
cleaned up in ntop-3.2