| SAS/C Cross-Platform Compiler and C++ Development System User's Guide, Release 6.50 |
NFS servers use a UNIX, or POSIX, file-permission system. This system gives each user a UID, a GID, and possibly several additional supplementary GIDs. Each file is assigned ownership by user
identification number (UID) and by group identification number (GID). Permissions for the file are set based on whether the user desiring access is the owner (has the same UID as the file), is in the
file's group (has a GID that matches the GID of the file), or is some other user. For each of these
three categories
(owner, group, and other) read, write, and execute permissions can be assigned.
To access files using NFS, your session on MVS or CMS must acquire UID and GID numbers that
correspond to some user on the NFS server network. You acquire these numbers by contacting a login server on the NFS network to ask permission to access files according to a username that
is known to that server. In many cases, contact with the NFS login server can be automatic the first time you access an NFS file. In other cases, you must issue the NFSLOGIN command to effect the
login.
The function of the login server is to check your identification and grant you access to the network. Once logged on, the login server functions as an NFS server and
provides access to the files located on the machine on which it resides. At this point you may also use the network to access files controlled by other NFS servers on other
machines.
If you have a RACF compatible security system running on your mainframe and your site administration has given you access to your NFS login server username, then
the security system can vouch for you and no password is required. Note that the login server username is not necessarily the same as your MVS or CMS userid. If you do not have a security system, then
you will need to enter your password during the login process.
In summary, the login process can involve three pieces of information:
The requirement for a password depends on whether a mainframe security system can provide authentication for login server
usernames. If the NFS client software can determine the other two pieces of information, either by default or by environment variables, then automatic login is possible. Otherwise, the NFSLOGIN
command must be used.
For example, if your NFS network is composed of UNIX machines, your UNIX username is
comkzz
, and your login server is a UNIX machine called
byrd.unx
, then the CSL NFS client software must contact
byrd.unx
and provide
comkzz
as the user name. If your MVS username is also COMKZZ (the same except for upper case), the mainframe security administrator has authorized you to use the
comkzz
username for NFS, and
byrd.unx
has been configured as the default login server at your site, then the NFS client library will log you in automatically
the
first time you try to use NFS.
If, on the other hand, your site does not have RACF, a password is required. In this case, you need to issue the NFSLOGIN command to enter
your password. See
NFSLOGIN for details.
After the login processing has succeeded, your session receives a UID and one or more GIDs.
These control your subsequent accesses to NFS files.
Copyright © 1998 by SAS Institute Inc., Cary, NC, USA. All rights reserved.
