The missing “crypt” symbol is probably this function: <http://pubs.opengroup.org/onlinepubs/9699919799/functions/crypt.html>. It is defined by the OS or a separate library, not by Python. You may need to link the “_crypt” Python module to the library that contains the function. E.g. in Glibc <http://man7.org/linux/man-pages/man3/crypt.3.html> you are meant to “link with -lcrypt”, although I suspect Python’s “setup.py” normally does that automatically.