Administration Reference

kas

Purpose

Introduction to the kas command suite

Description

The commands in the kas command suite are the administrative interface to the Authentication Server, which runs on each database server machine in a cell, maintains the Authentication Database, and provides the authentication tickets that client applications must present to AFS servers in order to obtain access to AFS data and other services.

There are several categories of commands in the kas command suite:

Commands to create, modify, examine and delete entries in the Authentication Database, including passwords: kas create, kas delete, kas examine, kas list, kas setfields, kas setkey, kas setpassword, and kas unlock
Commands to create, delete, and examine tokens and server tickets: kas forgetticket, kas listtickets, kas noauthentication, and kas stringtokey
A command to enter interactive mode: kas interactive
A command to trace Authentication Server operations: kas statistics
Commands to obtain help: kas apropos and kas help

Because of the sensitivity of information in the Authentication Database, the Authentication Server authenticates issuers of kas commands directly, rather than accepting the standard token generated by the Ticket Granting Service. Any kas command that requires administrative privilege prompts the issuer for a password. The resulting ticket is valid for six hours unless the maximum ticket lifetime for the issuer or the Authentication Server's Ticket Granting Service is shorter.

To avoid having to provide a password repeatedly when issuing a sequence of kas commands, enter interactive mode by issuing the kas interactive command, typing kas without any operation code, or typing kas followed by a user and cell name, separated by an at-sign (@; an example is kas smith.admin@abc.com). After prompting once for a password, the Authentication Server accepts the resulting token for every command issued during the interactive session. See the reference page for the kas interactive command for a discussion of when to use each method for entering interactive mode and of the effects of entering a session.

The Authentication Server maintains two databases on the local disk of the machine where it runs:

The Authentication Database (/usr/afs/db/kaserver.DB0) stores the information used to provide AFS authentication services to users and servers, including the password scrambled as an encryption key. The reference page for the kas examine command describes the information in a database entry.
An auxiliary file (/usr/afs/local/kaauxdb by default) that tracks how often the user has provided an incorrect password to the local Authentication Server. The reference page for the kas setfields command describes how the Authentication Server uses this file to enforce the limit on consecutive authentication failures. To designate an alternate directory for the file, use the kaserver command's -localfiles argument.

Options

The following arguments and flags are available on many commands in the kas suite. (Some of them are unavailable on commands entered in interactive mode, because the information they specify is established when entering interactive mode and cannot be changed except by leaving interactive mode.) The reference page for each command also lists them, but they are described here in greater detail.

-admin_username

Specifies the user identity under which to authenticate with the Authentication Server for execution of the command. If this argument is omitted, the kas command interpreter requests authentication for the identity under which the issuer is logged onto the local machine. Do not combine this argument with the -noauth flag.

-cell <cell name>

Names the cell in which to run the command. It is acceptable to abbreviate the cell name to the shortest form that distinguishes it from the other entries in the /usr/vice/etc/CellServDB file on the local machine. If the -cell argument is omitted, the command interpreter determines the name of the local cell by reading the following in order:

The value of the AFSCELL environment variable
The local /usr/vice/etc/ThisCell file

The -cell argument is not available on commands issued in interactive mode. The cell defined when the kas command interpreter enters interactive mode applies to all commands issued during the interactive session.

-help

Prints a command's online help message on the standard output stream. Do not combine this flag with any of the command's other options; when it is provided, the command interpreter ignores all other options, and only prints the help message.

-noauth

Establishes an unauthenticated connection to the Authentication Server, in which the Authentication Server treats the issuer as the unprivileged user anonymous. It is useful only when authorization checking is disabled on the server machine (during the installation of a server machine or when the bos setauth command has been used during other unusual circumstances). In normal circumstances, the Authentication Server allows only privileged users to issue most kas commands, and refuses to perform such an action even if the -noauth flag is provided. Do not combine this flag with the -admin_username and -password_for_admin arguments.

-password_for_admin

Specifies the password of the command's issuer. It is best to omit this argument, which echoes the password visibly in the command shell, instead enter the password at the prompt. Do not combine this argument with the -noauth flag.

-servers

Establishes a connection with the Authentication Server running on each specified database server machine, instead of on each machine listed in the local /usr/vice/etc/CellServDB file. In either case, the kas command interpreter then chooses one of the machines at random to contact for execution of each subsequent command. The issuer can abbreviate the machine name to the shortest form that allows the local name service to identify it uniquely.

Privilege Required

To issue most kas commands, the issuer must have the ADMIN flag set in his or her Authentication Database entry (use the kas setfields command to turn the flag on).

Related Information

CellServDB (client version)

kaserver.DB0 and kaserver.DBSYS1