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<TITLE>Administration Reference</TITLE>
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<META HTTP-EQUIV="updated" CONTENT="Tue, 03 Oct 2000 16:18:29">
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<A NAME="Top_Of_Page"></A>
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<H1>Administration Reference</H1>
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<HR><P ALIGN="center"> <A HREF="../index.htm"><IMG SRC="../books.gif" BORDER="0" ALT="[Return to Library]"></A> <A HREF="auarf002.htm#ToC"><IMG SRC="../toc.gif" BORDER="0" ALT="[Contents]"></A> <A HREF="auarf192.htm"><IMG SRC="../prev.gif" BORDER="0" ALT="[Previous Topic]"></A> <A HREF="#Bot_Of_Page"><IMG SRC="../bot.gif" BORDER="0" ALT="[Bottom of Topic]"></A> <A HREF="auarf194.htm"><IMG SRC="../next.gif" BORDER="0" ALT="[Next Topic]"></A> <A HREF="auarf284.htm#HDRINDEX"><IMG SRC="../index.gif" BORDER="0" ALT="[Index]"></A> <P>
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<P>
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<H2><A NAME="HDRKAS_SETFIELDS" HREF="auarf002.htm#ToC_207">kas setfields</A></H2>
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<A NAME="IDX5130"></A>
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<A NAME="IDX5131"></A>
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<A NAME="IDX5132"></A>
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<A NAME="IDX5141"></A>
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<A NAME="IDX5142"></A>
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<P><STRONG>Purpose</STRONG>
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<P>Sets optional characteristics in an Authentication Database entry
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<P><STRONG>Synopsis</STRONG>
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<PRE><B>kas setfields -name</B> <<VAR>name of user</VAR>>
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[<B>-flags</B> <<VAR>hex flag value or flag name expression</VAR>>]
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[<B>-expiration</B> <<VAR>date of account expiration</VAR>>]
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[<B>-lifetime</B> <<VAR>maximum ticket lifetime</VAR>>]
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[<B>-pwexpires</B> <<VAR>number days password is valid ([0..254])</VAR>>]
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[<B>-reuse</B> <<VAR>permit password reuse (yes/no)</VAR>>]
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[<B>-attempts</B> <<VAR>maximum successive failed login tries ([0..254])</VAR>>]
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[<B>-locktime</B> <<VAR>failure penalty [hh:mm or minutes]</VAR>>]
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[<B>-admin_username</B> <<VAR>admin principal to use for authentication</VAR>>]
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[<B>-password_for_admin</B> <<VAR>admin password</VAR>>] [<B>-cell</B> <<VAR>cell name</VAR>>]
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[<B>-servers</B> <<VAR>explicit list of authentication servers</VAR>><SUP>+</SUP>]
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[<B>-noauth</B>] [<B>-help</B>]
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<B>kas setf -na</B> <<VAR>name of user</VAR>> [<B>-f</B> <<VAR>hex flag value or flag name expression</VAR>>]
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[<B>-e</B> <<VAR>date of account expiration</VAR>>] [<B>-li</B> <<VAR>maximum ticket lifetime</VAR>>]
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[<B>-pw</B> <<VAR>number days password is valid ([0..254])</VAR>>]
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[<B>-r</B> <<VAR>permit password reuse (yes/no)</VAR>>]
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[<B>-at</B> <<VAR>maximum successive failed login tries ([0..254])</VAR>>]
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[<B>-lo</B> <<VAR>failure penalty [hh:mm or minutes]</VAR>>]
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[<B>-ad</B> <<VAR>admin principal to use for authentication</VAR>>]
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[<B>-pa</B> <<VAR>admin password</VAR>>] [<B>-c</B> <<VAR>cell name</VAR>>]
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[<B>-s</B> <<VAR>explicit list of authentication servers</VAR>><SUP>+</SUP>] [<B>-no</B>] [<B>-h</B>]
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<B>kas sf -na</B> <<VAR>name of user</VAR>> [<B>-f</B> <<VAR>hex flag value or flag name expression</VAR>>]
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[<B>-e</B> <<VAR>date of account expiration</VAR>>] [<B>-li</B> <<VAR>maximum ticket lifetime</VAR>>]
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[<B>-pw</B> <<VAR>number days password is valid ([0..254])</VAR>>]
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[<B>-r</B> <<VAR>permit password reuse (yes/no)</VAR>>]
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[<B>-at</B> <<VAR>maximum successive failed login tries ([0..254])</VAR>>]
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[<B>-lo</B> <<VAR>failure penalty [hh:mm or minutes]</VAR>>]
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[<B>-ad</B> <<VAR>admin principal to use for authentication</VAR>>]
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[<B>-pa</B> <<VAR>admin password</VAR>>] [<B>-c</B> <<VAR>cell name</VAR>>]
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[<B>-s</B> <<VAR>explicit list of authentication servers</VAR>><SUP>+</SUP>] [<B>-no</B>] [<B>-h</B>]
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</PRE>
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<P><STRONG>Description</STRONG>
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<P>The <B>kas setfields</B> command changes the Authentication Database
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entry for the user named by the <B>-name</B> argument in the manner
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specified by the various optional arguments, which can occur singly or in
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combination:
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<UL>
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<P><LI>To set the flags that determine whether the user has administrative
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privileges to the Authentication Server, can obtain a ticket, can change his
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or her password, and so on, include the <B>-flags</B> argument.
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<P><LI>To set when the Authentication Database entry expires, include the
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<B>-expiration</B> argument.
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<P><LI>To set the maximum ticket lifetime associated with the entry, include the
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<B>-lifetime</B> argument. The reference page for the
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<B>klog</B> command explains how this value interacts with others to
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determine the actual lifetime of a token.
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<P><LI>To set when the user's password expires, include the
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<B>-pwexpires</B> argument.
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<P><LI>To set whether the user can reuse any of the previous twenty passwords
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when creating a new one, include the <B>-reuse</B> argument.
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<P><LI>To set the maximum number of times the user can provide an incorrect
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password before the Authentication Server refuses to accept any more attempts
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(locks the issuer out), include the <B>-attempts</B> argument.
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After the sixth failed authentication attempt, the Authentication Server logs
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a message in the UNIX system log file (the <B>syslog</B> file or
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equivalent, for which the standard location varies depending on the operating
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system).
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<P><LI>To set how long the Authentication Server refuses to process
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authentication attempts for a locked-out user, set the <B>-locktime</B>
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argument.
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</UL>
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<P>The <B>kas examine</B> command displays the settings made with this
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command.
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<P><STRONG>Cautions</STRONG>
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<P>The password lifetime set with the <B>-pwexpires</B> argument begins at
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the time the user's password was last changed, rather than when this
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command is issued. It can therefore be retroactive. If, for
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example, a user changed her password 100 days ago and the password lifetime is
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set to 100 days or less, the password effectively expires immediately.
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To avoid retroactive expiration, instruct the user to change the password just
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before setting a password lifetime.
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<P>Administrators whose authentication accounts have the <TT>ADMIN</TT> flag
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enjoy complete access to the sensitive information in the Authentication
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Database. To prevent access by unauthorized users, use the
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<B>-attempts</B> argument to impose a fairly strict limit on the number of
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times that a user obtaining administrative tokens can provide an incorrect
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password. Note, however, that there must be more than one account in
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the cell with the <TT>ADMIN</TT> flag. The <B>kas unlock</B>
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command requires the <TT>ADMIN</TT> privilege, so it is important that the
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locked-out administrator (or a colleague) can access another
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<TT>ADMIN</TT>-privileged account to unlock the current account.
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<P>In certain circumstances, the mechanism used to enforce the number of
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failed authentication attempts can cause a lockout even though the number of
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failed attempts is less than the limit set by the <B>-attempts</B>
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argument. Client-side authentication programs such as <B>klog</B>
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and an AFS-modified login utility normally choose an Authentication Server at
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random for each authentication attempt, and in case of a failure are likely to
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choose a different Authentication Server for the next attempt. The
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Authentication Servers running on the various database server machines do not
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communicate with each other about how many times a user has failed to provide
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the correct password to them. Instead, each Authentication Server
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maintains its own separate copy of the auxiliary database file
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<B>kaserverauxdb</B> (located in the <B>/usr/afs/local</B> directory
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by default), which records the number of consecutive authentication failures
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for each user account and the time of the most recent failure. This
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implementation means that on average each Authentication Server knows about
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only a fraction of the total number of failed attempts. The only way to
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avoid allowing more than the number of attempts set by the
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<B>-attempts</B> argument is to have each Authentication Server allow only
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some fraction of the total. More specifically, if the limit on failed
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attempts is <I>f</I>, and the number of Authentication Servers is
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<I>S</I>, then each Authentication Server can only permit a number of
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attempts equal to <I>f</I> divided by <I>S</I> (the Ubik
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synchronization site for the Authentication Server tracks any remainder,
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<I>fmodS</I>).
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<P>Normally, this implementation does not reduce the number of allowed
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attempts to less than the configured limit (<I>f</I>). If one
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Authentication Server refuses an attempt, the client contacts another instance
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of the server, continuing until either it successfully authenticates or has
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contacted all of the servers. However, if one or more of the
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Authentication Server processes is unavailable, the limit is effectively
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reduced by a percentage equal to the quantity <I>U</I> divided by
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<I>S</I>, where <I>U</I> is the number of unavailable servers and
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<I>S</I> is the number normally available.
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<P>To avoid the undesirable consequences of setting a limit on failed
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authentication attempts, note the following recommendations:
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<UL>
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<P><LI>Do not set the <B>-attempts</B> argument (the limit on failed
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authentication attempts) too low. A limit of nine failed attempts is
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recommended for regular user accounts, to allow three failed attempts per
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Authentication Server in a cell with three database server machines.
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<P><LI>Set fairly short lockout times when including the <B>-locktime</B>
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argument. Although guessing passwords is a common method of attack, it
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is not a very sophisticated one. Setting a lockout time can help
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discourage attackers, but excessively long times are likely to be more of a
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burden to authorized users than to potential attackers. A lockout time
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of 25 minutes is recommended for regular user accounts.
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<P><LI>Do not assign an infinite lockout time on an account (by setting the
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<B>-locktime</B> argument to <B>0</B> [zero]) unless there is a highly
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compelling reason. Such accounts almost inevitably become locked at
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some point, because each Authentication Server never resets the account's
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failure counter in its copy of the <B>kaauxdb</B> file (in contrast, when
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the lockout time is not infinite, the counter resets after the specified
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amount of time has passed since the last failed attempt to that Authentication
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Server). Furthermore, the only way to unlock an account with an
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infinite lockout time is for an administrator to issue the <B>kas
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unlock</B> command. It is especially dangerous to set an infinite
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lockout time on an administrative account; if all administrative accounts
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become locked, the only way to unlock them is to shut down all instances of
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the Authentication Server and remove the <B>kaauxdb</B> file on
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each.
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</UL>
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<P><STRONG>Options</STRONG>
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<DL>
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<P><DT><B>-name
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</B><DD>Names the Authentication Database account for which to change
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settings.
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<P><DT><B>-flags
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</B><DD>Sets one or more of four toggling flags, adding them to any flags
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currently set. Either specify one or more of the following strings, or
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specify a hexidecimal number that combines the indicated values. To
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return all four flags to their defaults, provide a value of <B>0</B>
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(zero). To set more than one flag at once using the strings, connect
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them with plus signs (example: <B>NOTGS+ADMIN+CPW</B>). To
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remove all the current flag settings before setting new ones, precede the list
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with an equal sign (example: <B>=NOTGS+ADMIN+CPW</B>).
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<DL>
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<P><DT><B>ADMIN
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</B><DD>The user is allowed to issue privileged <B>kas</B> commands
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(hexadecimal equivalent is <B>0x004</B>, default is
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<B>NOADMIN</B>).
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<A NAME="IDX5143"></A>
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<P><DT><B>NOTGS
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</B><DD>The Authentication Server's Ticket Granting Service (TGS) refuses to
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issue tickets to the user (hexadecimal equivalent is <B>0x008</B>, default
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is <B>TGS</B>).
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<A NAME="IDX5144"></A>
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<P><DT><B>NOSEAL
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</B><DD>The Ticket Granting Service cannot use the contents of this entry's
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key field as an encryption key (hexadecimal equivalent is <B>0x020</B>,
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default is <B>SEAL</B>).
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<A NAME="IDX5145"></A>
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<P><DT><B>NOCPW
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</B><DD>The user cannot change his or her own password or key (hexadecimal
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equivalent is <B>0x040</B>, default is <B>CPW</B>).
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<A NAME="IDX5146"></A>
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</DL>
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<P><DT><B>-expiration
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</B><DD>Determines when the entry itself expires. When a user entry
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expires, the user becomes unable to log in; when a server entry such as
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<B>afs</B> expires, all server processes that use the associated key
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become inaccessible. Provide one of the three acceptable values:
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<DL>
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<P><DT><B>never
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</B><DD>The account never expires (the default).
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<P><DT><B><VAR>mm/dd/yyyy</VAR>
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</B><DD>Sets the expiration date to 12:00 a.m. on the
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indicated date (month/day/year). Examples: <B>01/23/1999</B>,
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<B>10/07/2000</B>.
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<P><DT><B>"<VAR>mm/dd/yyyy hh:MM</VAR>"
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</B><DD>Sets the expiration date to the indicated time (hours:minutes) on
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the indicated date (month/day/year). Specify the time in 24-hour format
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(for example, <B>20:30</B> is 8:30 p.m.) Date
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format is the same as for a date alone. Surround the entire instance
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with quotes because it contains a space. Examples:
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<B>"01/23/1999 22:30"</B>, <B>"10/07/2000
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3:45"</B>.
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</DL>
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<P>
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<P>Acceptable values for the year range from <B>1970</B> (1 January 1970
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is time 0 in the standard UNIX date representation) through <B>2037</B>
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(2037 is the maximum because the UNIX representation cannot accommodate dates
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later than a value in February 2038).
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<P><DT><B>-lifetime
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</B><DD>Specifies the maximum lifetime that the Authentication Server's
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Ticket Granting Service (TGS) can assign to a ticket. If the account
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belongs to a user, this value is the maximum lifetime of a token issued to the
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user. If the account corresponds to a server such as <B>afs</B>,
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this value is the maximum lifetime of a ticket that the TGS issues to clients
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for presentation to the server during mutual authentication.
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<P>Specify an integer that represents a number of seconds (<B>3600</B>
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equals one hour), or include a colon in the number to indicate a number of
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hours and minutes (<B>10:00</B> equals 10 hours). If this
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argument is omitted, the default setting is 100:00 hours (360000
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seconds).
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<P><DT><B>-pwexpires
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</B><DD>Sets the number of days after the user's password was last changed
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that it remains valid. Provide an integer from the range <B>1</B>
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through <B>254</B> to specify the number of days until expiration, or the
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value <B>0</B> to indicate that the password never expires (the
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default).
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<P>When the password expires, the user is unable to authenticate, but has 30
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days after the expiration date in which to use the <B>kpasswd</B> command
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to change the password (after that, only an administrator can change it by
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using the <B>kas setpassword</B> command). Note that the clock
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starts at the time the password was last changed, not when the <B>kas
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setfields</B> command is issued. To avoid retroactive expiration,
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have the user change the password just before issuing a command that includes
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this argument.
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<P><DT><B>-reuse
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</B><DD>Specifies whether or not the user can reuse any of his or her last 20
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passwords. The acceptable values are <B>yes</B> to allow reuse of
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old passwords (the default) and <B>no</B> to prohibit reuse of a password
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that is similar to one of the previous 20 passwords.
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<P><DT><B>-attempts
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</B><DD>Sets the number of consecutive times the user can provide an incorrect
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password during authentication (using the <B>klog</B> command or a login
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utility that grants AFS tokens). When the user exceeds the limit, the
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Authentication Server rejects further attempts (locks the user out) for the
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amount of time specified by the <B>-locktime</B> argument. Provide
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an integer from the range <B>1</B> through <B>254</B> to specify the
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number of failures allowed, or <B>0</B> to indicate that there is no limit
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on authentication attempts (the default value).
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<P><DT><B>-locktime
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</B><DD>Specifies how long the Authentication Server refuses authentication
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attempts from a user who has exceeded the failure limit set by the
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<B>-attempts</B> argument.
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<P>Specify a number of hours and minutes (<VAR>hh</VAR>:<VAR>mm</VAR>) or
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minutes only (<VAR>mm</VAR>), from the range <B>01</B> (one minute) through
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<B>36:00</B> (36 hours). The <B>kas</B> command
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interpreter automatically reduces any larger value to <B>36:00</B>
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and also rounds up any non-zero value to the next higher multiple of
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8.5 minutes. A value of <B>0</B> (zero) sets an infinite
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lockout time; an administrator must issue the <B>kas unlock</B>
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command to unlock the account.
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<P><DT><B>-admin_username
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</B><DD>Specifies the user identity under which to authenticate with the
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Authentication Server for execution of the command. For more details,
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see the introductory <B>kas</B> reference page.
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<P><DT><B>-password_for_admin
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</B><DD>Specifies the password of the command's issuer. If it is
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omitted (as recommended), the <B>kas</B> command interpreter prompts for
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it and does not echo it visibly. For more details, see the introductory
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<B>kas</B> reference page.
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<P><DT><B>-cell
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</B><DD>Names the cell in which to run the command. For more details, see
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the introductory <B>kas</B> reference page.
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<P><DT><B>-servers
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</B><DD>Names each machine running an Authentication Server with which to
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establish a connection. For more details, see the introductory
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<B>kas</B> reference page.
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<P><DT><B>-noauth
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</B><DD>Assigns the unprivileged identity <B>anonymous</B> to the
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issuer. For more details, see the introductory <B>kas</B> reference
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page.
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<P><DT><B>-help
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</B><DD>Prints the online help for this command. All other valid options
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are ignored.
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</DL>
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<P><STRONG>Examples</STRONG>
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<P>In the following example, an administrator using the <B>admin</B>
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account grants administrative privilege to the user <B>smith</B>, and sets
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the Authentication Database entry to expire at midnight on 31 December
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2000.
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<PRE> %<B> kas setfields -name smith -flags ADMIN -expiration 12/31/2000</B>
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Password for admin:
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</PRE>
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<P>In the following example, an administrator using the <B>admin</B>
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account sets the user <B>pat</B>'s password to expire in 60 days from
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when it last changed, and prohibits reuse of passwords.
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<PRE> %<B> kas setfields -name pat -pwexpires 60 -reuse no</B>
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Password for admin:
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</PRE>
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<P><STRONG>Privilege Required</STRONG>
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<P>The issuer must have the <TT>ADMIN</TT> flag set on his or her
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Authentication Database entry.
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<P><STRONG>Related Information</STRONG>
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<P><A HREF="auarf046.htm#HDRKASERVERAUXDB">kaserverauxdb</A>
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<P><A HREF="auarf181.htm#HDRKAS_INTRO">kas</A>
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<P><A HREF="auarf185.htm#HDRKAS_EXAMINE">kas examine</A>
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<P><A HREF="auarf194.htm#HDRKAS_SETPASSWORD">kas setpassword</A>
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<P><A HREF="auarf197.htm#HDRKAS_UNLOCK">kas unlock</A>
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<P><A HREF="auarf200.htm#HDRKLOG">klog</A>
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