ThisCell - Defines the local cell name
The
ThisCell file defines the local cell name. There are two versions of
this file, one for a AFS client and one for an AFS server.
The client version of the
ThisCell file defines the complete Internet
domain-style name (for example, "example.com") of the cell to which
the local client machine belongs. It must reside in the
/etc/openafs
directory on every AFS client machine. To change a client machine's cell
membership, edit the file and reboot the machine.
The file is in ASCII format and contains a character string on a single line.
The
OpenAFS Quick Start Guide instructs the administrator to create it
during the installation of each client machine.
The client machine's cell membership determines three defaults important to its
functioning:
- •
- The cell in which the machine's users authenticate by
default. The effect is two-fold:
- •
- The AFS-modified login utilities and the klog command
interpreter contact an Authentication Server in the cell named in the
ThisCell file (unless -cell argument to the klog
command specifies an alternate cell).
- •
- The command interpreters combine the cell name with the
password that the user provides, generating an encryption key from the
combination. For authentication to succeed, both the cell name and
password must match the ones used to generate the user's encryption key
stored in the Authentication Database.
- •
- The cell the Cache Manager considers its local, or home,
cell. By default, the Cache Manager allows programs that reside in its
home cell to run with setuid permission, but not programs from foreign
cells. For more details, see the fs getcellstatus and fs
setcell reference pages.
- •
- Which AFS server processes the local AFS command
interpreters contact by default as they execute commands issued on the
machine.
The client version of the
ThisCell file is distinct from the server
version, which resides in the
/etc/openafs/server directory on each AFS
server machine. If a server machine also runs as a client, it is acceptable
for the server and client versions of the file on the same machine to name
different cells. However, the behavior that results from this configuration
can be more confusing than useful.
The server version of the
ThisCell file defines the complete Internet
domain-style name (for example, "example.com") of the cell to which
the server machine belongs. It must reside in the
/etc/openafs/server
directory on every AFS server machine.
The file is in ASCII format and contains a character string on a single line.
The initial version of the file is created with the
bos
setcellname command during the installation of the cell's first file
server machine, and the
OpenAFS Quick Start Guide includes instructions
for copying it over to additional server machine during their installation.
The only reason to edit the file is as part of changing the cell's name, which
is strongly discouraged because of the large number of configuration changes
involved. In particular, changing the cell name requires rebuilding the entire
Authentication Database, because the Authentication Server combines the cell
name it finds in this file with each user and server password and converts the
combination into an encryption key before recording it in the Database.
bos_setcellname(8),
fs_getcellstatus(1),
fs_setcell(1)
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