Setting a Client Machine's Cell Membership
| Chapter 10. Administering Client Machines and the Cache Manager |

## Setting a Client Machine's Cell Membership

Each client machine belongs to a particular cell, as named in the /usr/vice/etc/ThisCell on its local disk. The machine's cell membership determines three defaults important to users of the machine:

- The cell for which users of the machine obtain tokens (authenticate) when they use the login program or issue the klog command. There are two effects:

  - The klog program and AFS-modified login utilities contact an Authentication Server in the cell named in the ThisCell file.

  - The klog program and AFS-modified login utilities combine the contents of the ThisCell file with the password that the user provides, generating an encryption key from the combination. The user's entry in the Authentication Database includes an encryption key also generated from the combination of password and cell name. If the cell name in the ThisCell file is incorrect, users cannot authenticate even if they provide the correct password.

- The cell the Cache Manager considers its local, or home, cell. The Cache Manager allows programs from its local cell to run with setuid permission, but not programs from foreign cells, as discussed further in Determining if a Client Can Run Setuid Programs.

- The default database server machines that are contacted by the AFS command interpreters running on this machine.

### To display a client machine's cell membership

1. Use a text editor or the cat command to display the contents of the /usr/vice/etc/ThisCell file.

          % cat /usr/vice/etc/ThisCell

### To set a client machine's cell membership

1. Become the local superuser root on the machine, if you are not already, by issuing the su command.

          % su root
          Password: <root_password>

2. Using a text editor, replace the cell name in the /usr/vice/etc/ThisCell file.

3. (Optional.) Reboot the machine to enable the Cache Manager to use the new cell name immediately; the appropriate command depends on the machine's system type. The klog program, AFS-modified login utilities, and the AFS command interpreters use the new cell name the next time they are invoked; no reboot is necessary.

          # sync
          # shutdown

Setting the File Server Probe Interval |  | Forcing the Update of Cached Data