Exported file systems with NFS Introduction NFS (Network File System) is the de facto standard _U_n_i_x to _U_n_i_x file sharing protocol. This means that _L_i_n_u_x can be a file server for any _U_n_i_x system out there. This configuration screen allows you to "pub- lish" some specific parts of your file system tree. 11.. EExxppoorrttiinngg ffiillee ssyysstteemmss Your _L_i_n_u_x system manage its files under a large big tree. You can specify which subdirectories you are making available to which machine. Ultimately, you can specify that you export the root "/" with an empty list of machine. This means any machine will be able to access your files. By specifying one or more machines, you are restricting access. 22.. OOppttiioonnss For each path you export, you can specify a list of hosts and a set of options associated with these hosts. If more than one host share the same option set, you can enter them on the line, using the comma as the separator. Each option is presented with a check box. Here they are +o _M_a_y _w_r_i_t_e Writing to this directory is allowed for this client. +o _R_o_o_t _p_r_i_v_i_l_e_g_e Withouth this option, all requests from user ID 0 (root) on the client are mapped to uid NOBODY_UID (a compile-time option) on the server. Unless you have full trust in the client security, you don't give away this option. +o _T_r_a_n_s_l_a_t_e _s_y_m_b_o_l_i_c _l_i_n_k_s Convert absolute symbolic links (where the link contents start with a slash) into relative links by prepending the necessary number of ../'s to get from the directory containing the link to the root on the server. This has sub- tle, perhaps questionable, semantics when the file hierarchy is not mounted at its root. +o _R_e_q_u_e_s_t _a_c_c_e_s_s _f_r_o_m _s_e_c_u_r_e _p_o_r_t Connexion will be only accepted if they originate from secure port on the client. 33.. UUssiinngg wwiilldd ccaarrddss You may want to export a given path to all machine in a given domain. You are allowed to enter *.a_domain.com for example. Beware that the * does not match the dots. So if you want to give access to all machine of a_domain.com and all machines of all sub-domain of a_domain.com, then you must enter: *.a_domain.com,*.*.a_domain.com 44.. MMaacchhiinnee ttoo mmaacchhiinnee NFS introduce a fairly different approach to normal PC networking. Most PC file sharing protocols establish a relation between one user and one or several servers. The machine used by the user is not relevant. Given that many PCs are running single user operating systems this scheme make sens. _U_n_i_x and _L_i_n_u_x are multi-user systems. NFS configuration is a machine to machine issue. One NFS server is granting access to different machines either one by one or to all machine of a given network. Once an NFS relation is activated between one server machine and one client, all users on the client have access to the server, in the same way they have access to files and directories on the client machine. If fact one user one the client machine will have about the same access as if he was logged in the server. His access will be limited to the different part of the file system exported by the server.