Provided by: openafs-krb5_1.8.0~pre5-1ubuntu1.2_amd64 
NAME
klog.krb5 - Authenticates to Kerberos and obtains a token
SYNOPSIS
klog.krb5 [-x] [-principal <user name>]
[-password <user's password>] [-cell <cell name>]
[-k <realm>] [-pipe] [-silent]
[-lifetime <ticket lifetime in hh[:mm[:ss]]>]
[-setpag] [-tmp] [-noprdb] [-unwrap] [-help]
klog.krb5 [-x] [-pr <user name>]
[-pa <user's password>]
[-c <cell name>]
[-k <realm>] [-pi] [-si]
[-l <ticket lifetime in hh[:mm[:ss]]>]
[-se] [-t] [-n] [-u] [-h]
DESCRIPTION
The klog.krb5 command obtains a Kerberos v5 ticket from a Kerberos KDC and, from the ticket, an AFS token
and then stores it in the Cache Manager. The Cache Manager keeps the token in kernel memory and uses it
when obtaining authenticated access to the AFS filespace. This command does not affect the issuer's
identity (UNIX UID) on the local file system.
By default, the command interpreter obtains a token for the AFS user name that matches the issuer's local
user name. To specify an alternate user, include the -principal argument. The user named by the
-principal argument does not have to appear in the local password file (the /etc/passwd file or
equivalent).
By default, the command interpreter obtains a token for the local cell, as defined by the AFSCELL
environment variable set in the command shell or by the /etc/openafs/ThisCell file on the local machine.
To specify an alternate cell, include the -cell argument. A user can have tokens in multiple cells
simultaneously, but only one token per cell per connection to the client machine. If the user's
credential structure already contains a token for the requested cell, the token resulting from this
command replaces it.
By default, the command interpreter obtains a Kerberos ticket for the local realm. To specify a
different Kerberos realm, include the -k argument. The Kerberos realm name need not match the AFS cell
name. klog.krb5 will request a ticket for the principal "afs/cell" where cell is the cell name for which
the user is requesting tokens, falling back on the principal "afs" if that principal does not work.
The lifetime of the token resulting from this command is the smallest of the following:
• The lifetime specified by the issuer with the -lifetime argument if that argument was given.
• The maximum ticket lifetime recorded for the "afs/cell" principal in thet Kerberos database.
• The maximum ticket lifetime recorded in the specified user's Kerberos database entry.
CAUTIONS
By default, this command does not create a new process authentication group (PAG); see the description of
the pagsh command to learn about PAGs. If a cell does not use an AFS-modified login utility, users must
include -setpag option to this command, or issue the pagsh command before this one, to have their tokens
stored in a credential structure that is identified by PAG rather than by local UID. Users should be
aware that -setpag will not work on some systems, most notably recent Linux systems, and using pagsh is
preferrable and more reliable.
When a credential structure is identified by local UID, the potential security exposure is that the local
superuser "root" can use the UNIX su command to assume any other identity and automatically inherit the
tokens associated with that UID. Identifying the credential structure by PAG makes it more difficult
(but not impossible) for the local superuser to obtain tokens of other users.
If the -password argument is used, the specified password cannot begin with a hyphen, because it is
interpreted as another option name. Use of the -password argument is not recommended in any case.
By default, it is possible to issue this command on a properly configured NFS client machine that is
accessing AFS via the NFS/AFS Translator, assuming that the NFS client machine is a supported system
type. However, if the translator machine's administrator has enabled UID checking by including the
-uidcheck on argument to the fs exportafs command, the command fails with an error message similar to the
following:
Warning: Remote pioctl to <translator_machine> has failed (err=8). . .
Unable to authenticate to AFS because a pioctl failed.
Enabling UID checking means that the credential structure in which tokens are stored on the translator
machine must be identified by a UID that matches the local UID of the process that is placing the tokens
in the credential structure. After the klog.krb5 command interpreter obtains the token on the NFS
client, it passes it to the remote executor daemon on the translator machine, which makes the system call
that stores the token in a credential structure on the translator machine. The remote executor generally
runs as the local superuser "root", so in most cases its local UID (normally zero) does not match the
local UID of the user who issued the klog.krb5 command on the NFS client machine.
Issuing the klog.krb5 command on an NFS client machine creates a security exposure: the command
interpreter passes the token across the network to the remote executor daemon in clear text mode.
OPTIONS
-x Appears only for backwards compatibility. Its former function is now the default behavior of this
command.
-principal <user name>
Specifies the user name to authenticate. If this argument is omitted, the default value is the local
user name.
-password <user's password>
Specifies the issuer's password (or that of the alternate user identified by the -principal
argument). Omit this argument to have the command interpreter prompt for the password, in which case
it does not echo visibly in the command shell.
-cell <cell name>
Specifies the cell for which to obtain a token. During a single login session on a given machine, a
user can be authenticated in multiple cells simultaneously, but can have only one token at a time for
each of them (that is, can only authenticate under one identity per cell per session on a machine).
It is acceptable to abbreviate the cell name to the shortest form that distinguishes it from the
other cells listed in the /etc/openafs/CellServDB file on the client machine on which the command is
issued.
If this argument is omitted, the command is executed in the local cell, as defined
• First, by the value of the environment variable AFSCELL.
• Second, in the /etc/openafs/ThisCell file on the client machine on which the command is issued.
-k <realm>
Obtain tickets and tokens from the <realm> Kerberos realm. If this option is not given, klog.krb5
defaults to using the default local realm. The Kerberos realm name need not match the AFS cell name.
-pipe
Suppresses all output to the standard output stream, including prompts and error messages. The
klog.krb5 command interpreter expects to receive the password from the standard input stream. Do not
use this argument; it is designed for use by application programs rather than human users.
-silent
Suppresses some of the trace messages that the klog.krb5 command produces on the standard output
stream by default. It still reports on major problems encountered.
-lifetime <ticket lifetime
Requests a specific lifetime for the token. Provide a number of hours and optionally minutes and
seconds in the format hh[:mm[:ss]].
-setpag
Creates a process authentication group (PAG) prior to requesting authentication. The token is
associated with the newly created PAG.
-tmp
Creates a Kerberos-style ticket file rather than only obtaining tokens. The ticket file will be
stored in the default Kerberos ticket cache location, which is usually in the /tmp directory of the
local machine (but depends on the Kerberos implementation used).
-noprdb
By default, klog.krb5 looks up the user's AFS ID in the Protection Server and associates the token
with that AFS ID. This is helpful when looking at the output of commands like tokens but is not
required. If this option is given, this behavior is suppressed and klog.krb5 will store the token
under a generic name. You may wish this if, for example, you have problems contacting the Protection
Server for an AFS cell for some reason.
-unwrap
Normally, klog.krb5 uses the Kerberos service ticket for the AFS principal as the AFS token. If this
option is given, klog.krb5 creates a different, simplified AFS token form based on the service ticket
(the so-called "rxkad 2b" token). Normally, this is not necessary. However, if you are using older
OpenAFS software that cannot handle large ticket sizes in conjunction with Active Directory as the
Kerberos server, using -unwrap can shrink the AFS token size so that older software can handle it
more easily.
-help
Prints the online help for this command. All other valid options are ignored.
OUTPUT
If the -tmp flag is included, the following message confirms that a Kerberos ticket cache was created:
Wrote ticket file to /tmp/krb5cc_1000_rENJoZ
The path to the cache will vary, of course.
EXAMPLES
Most often, this command is issued without arguments. The appropriate password is for the person
currently logged into the local system. The ticket's lifetime is calculated as described in
"DESCRIPTION".
% klog.krb5
Password for user@EXAMPLE.ORG:
The following example authenticates the user as admin in the Example Corporation's test cell:
% klog.krb5 -principal admin -cell test.example.com
Password for admin@EXAMPLE.COM:
In the following, the issuer requests a ticket lifetime of 104 hours 30 minutes (4 days 8 hours 30
minutes).
% klog.krb5 -lifetime 104:30
Password for user@EXAMPLE.ORG:
PRIVILEGE REQUIRED
None
SEE ALSO
aklog(1), fs_exportafs(1), pagsh(1), tokens(1)
COPYRIGHT
IBM Corporation 2000. <http://www.ibm.com/> All Rights Reserved.
This documentation is covered by the IBM Public License Version 1.0. It was converted from HTML to POD
by software written by Chas Williams and Russ Allbery, based on work by Alf Wachsmann and Elizabeth
Cassell.
OpenAFS 2019-11-22 KLOG.KRB5(1)