/usr/include/SFML/Network/ is in libsfml-dev 1.6+dfsg1-2ubuntu2.
This file is owned by root:root, with mode 0o755.
..
/usr/include/SFML/Network/Ftp.hpp
/usr/include/SFML/Network/Http.hpp
/usr/include/SFML/Network/IPAddress.hpp
/usr/include/SFML/Network/Packet.hpp
/usr/include/SFML/Network/Selector.hpp
/usr/include/SFML/Network/Selector.inl
/usr/include/SFML/Network/SelectorBase.hpp
/usr/include/SFML/Network/SocketHelper.hpp
/usr/include/SFML/Network/SocketTCP.hpp
/usr/include/SFML/Network/SocketUDP.hpp
/usr/include/SFML/Network/Sockets.hpp
/usr/include/SFML/Network/Unix/
/usr/include/SFML/Network/Unix/SocketHelper.hpp
/usr/include/SFML/Network/Win32/
/usr/include/SFML/Network/Win32/SocketHelper.hpp