MUNGED(8) MUNGE Uid 'N' Gid Emporium MUNGED(8)NAMEmunged - MUNGE daemon
SYNOPSISmunged [OPTION]...
DESCRIPTION
The munged daemon is responsible for authenticating local MUNGE clients
and servicing their credential encode & decode requests. All munged
daemons within a security realm share a secret key. This key is used
to protect the contents of a credential.
When a credential is created, munged embeds metadata within it includ‐
ing the effective UID and GID of the requesting client (as determined
by munged) and the current time (as determined by the local clock). It
then compresses the data, computes a message authentication code,
encrypts the data, and base64-encodes the result before returning the
credential to the client.
When a credential is validated, munged first checks the message authen‐
tication code to ensure the credential has not been subsequently
altered. Next, it checks the embedded UID/GID restrictions to deter‐
mine whether the requesting client is allowed to decode it. Then, it
checks the embedded encode time against the current time; if this dif‐
ference exceeds the embedded time-to-live, the credential has expired.
Finally, it checks whether this credential has been previously decoded
on this host; if so, the credential has been replayed. If all checks
pass, the credential metadata and payload are returned to the client.
OPTIONS-h, --help
Display a summary of the command-line options.
-L, --license
Display license information.
-V, --version
Display version information.
-f, --force
Force the daemon to run if at all possible. This overrides
warnings for an existing local domain socket, a lack of entropy
for the PRNG, and insecure file/directory permissions. Use with
caution as overriding these warnings can affect security.
-F, --foreground
Run the daemon in the foreground.
-M, --mlockall
Lock all current and future pages in the virtual memory address
space. Access to locked pages will never be delayed by a page
fault. This can improve performance and help the daemon remain
responsive when the system is under heavy memory pressure. This
typically requires root privileges or the CAP_IPC_LOCK capabil‐
ity.
-S, --socket path
Specify the local domain socket for communicating with clients.
--auth-server-dir directory
Specify an alternate directory in which the daemon will create
the pipe used to authenticate clients. The recommended permis‐
sions for this directory are 0711. This option is only valid on
platforms where client authentication is performed via a file-
descriptor passing mechanism.
--auth-client-dir directory
Specify an alternate directory in which clients will create the
file used to authenticate themselves to the daemon. The recom‐
mended permissions for this directory are 1733. This option is
only valid on platforms where client authentication is performed
via a file-descriptor passing mechanism.
--benchmark
Disable recurring timers in order to reduce some noise while
benchmarking. This affects the PRNG entropy pool, supplementary
group mapping, and credential replay hash. Do not enable this
option when running in production.
--group-check-mtime boolean
Specify whether the modification time of /etc/group should be
checked before updating the supplementary group membership map‐
ping. If this value is non-zero, the check will be enabled and
the mapping will not be updated unless the file has been modi‐
fied since the last update.
--group-update-time integer
Specify the number of seconds between updates to the supplemen‐
tary group membership mapping; this mapping is used when
restricting credentials by GID. A value of 0 causes it to be
computed initially but never updated (unless triggered by a
SIGHUP). A value of -1 causes it to be disabled.
--key-file file
Specify an alternate secret key file.
--num-threads integer
Specify the number of threads to spawn for processing credential
requests.
--syslog
Redirect log messages to syslog when the daemon is running in
the background.
SIGNALS
SIGHUP Immediately update the supplementary group membership mapping
instead of waiting for the next scheduled update; this mapping
is used when restricting credentials by GID.
SIGTERM
Terminate the daemon.
NOTES
All clocks within a security realm must be kept in sync within the cre‐
dential time-to-live setting.
While munged prevents a given credential from being decoded on a par‐
ticular host more than once, nothing prevents a credential from being
decoded on multiple hosts within the security realm before it expires.
AUTHOR
Chris Dunlap <cdunlap@llnl.gov>
COPYRIGHT
Copyright (C) 2007-2013 Lawrence Livermore National Security, LLC.
Copyright (C) 2002-2007 The Regents of the University of California.
MUNGE is free software: you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free
Software Foundation, either version 3 of the License, or (at your
option) any later version.
Additionally for the MUNGE library (libmunge), you can redistribute it
and/or modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation, either version 3
of the License, or (at your option) any later version.
SEE ALSOmunge(1), remunge(1), unmunge(1), munge(3), munge_ctx(3),
munge_enum(3), munge(7).
https://munge.googlecode.com/
munge-0.5.11 2013-08-27 MUNGED(8)
