/usr/lib/pyshared/python2.7/_arc.so is in nordugrid-arc-python 1.1.1-1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/pyshared/python2.7/../../python2.7/dist-packages/_arc.so
/usr/lib/pyshared/python2.7/../../python2.7/dist-packages/_arc.so