Differences between Unix and AFS - NFS/AFS

As AFS is not a native Unix file system, separate installation and management are required. Unix users and/or data may be located either on a local Unix disk partition or on AFS volumes or on a NFS file system. In a Unix system both local disk and NFS file systems are treated in the same way with regard to protections that differ from AFS file system ownership handling. To access NFS files, AFS supports a translator managed by the knfs command. No detailed information on the translator is given in this document.

AFS users may be authenticated in two differents ways:

• by the AFS login program
• by the following Unix steps: issue pagsh to create space for token holding issue klog to authenticate

AFS and Unix protections are completely different: Unix relies on mode bits while AFS relies on ACLs and interacts with Unix mode bits. Unix mode bits specify for each file the following protections:

UNIX MODE BITS: rwx for ugo --->
                read|write|execute for user|group|others

AFS access in controlled by 7 ACls that apply to the whole directory and provides up to 20 user/group definitions. The provided ACLs are:

AFS ACLs: rldiwka for 'groups' --->
          read|lookup|insert|delete|write|lock|administer for adm|any|user
          (Default: system:administrators|system:anyuser|user)

When running ftp, rcp, rsh, rlogin on an AFS machine, if the user is not AFS authenticated on the remote node (in which case direct access is given), the following message is displayed:

Warning: unable to authenticate

in this case file access is granted only as system:anyuser member.