tailieunhanh - Managing NFS and NIS 2nd phần 6

và máy chủ hoặc kích thước khối hệ thống tập tin của khách hàng. Nó được lựa chọn dựa vào kích thước hiệu quả xử lý bởi các giao thức mạng lưới giao thông vận tải, và thường là 8 kilobytes cho NFS phiên bản 2, và 32 kilobytes cho NFS phiên bản 3. Các khách hàng NFS thực hiện kế hoạch này, bộ đệm | Managing NFS and NIS depends upon the sensitivity of the data on the clients if you don t want other users to see the private data then you must treat the client machine like a server. The etc and .rhosts files in each user s home directory define the set of trusted hosts users and user-host pairs for each system. Again trust and transparent access are granted by the machine being accessed remotely so these configuration files vary from host to host. The .rhosts file is maintained by each user and specifies a list of hosts or user-host pairs that are also parsed for determining if a host or user is trusted. Enabling transparent access Both rlogin and rsh use the ruserok library routine to bypass the normal login and password security mechanism. The ruserok routine is invoked on the server side of a connection to see if the remote user gets transparent . no password prompt access. To understand the semantics let s look at its function prototype int ruserok const char rhost int suser const char ruser const char luser The rhost parameter is the name of the remote host from where the remote user is. The ruser parameter is the login name of the remote user. The luser parameter is the name of local login name that the remote user wants transparent access to. Often luser and ruser are the same but not always. The suser parameter is set to 1 if the UID of luser is 0 . superuser. Otherwise suser is set to 0. ruserok checks first if luser exists . does getpwnam return success for luser It then determines if the remote user and hostname given are trusted on the local host it is usually called by the remote daemon for these utilities during its startup. If the user or host are not trusted then the user must supply a password to log in or get Permission denied errors when attempting to use rsh. If the remote host trusts the user and host execution or login proceeds without any other verification of the user s identity. The file contains .