NAME¶
munged - MUNGE daemon
SYNOPSIS¶
munged [
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 including
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
authentication code to ensure the credential has not been subsequently
altered. Next, it checks the embedded UID/GID restrictions to determine
whether the requesting client is allowed to decode it. Then, it checks the
embedded encode time against the current time; if this difference 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 capability.
- -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 permissions 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 recommended 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 mapping. If
this value is non-zero, the check will be enabled and the mapping will not
be updated unless the file has been modified since the last update.
- --group-update-time integer
- Specify the number of seconds between updates to the supplementary 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 credential
time-to-live setting.
While
munged prevents a given credential from being decoded on a
particular 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 ALSO¶
munge(1),
remunge(1),
unmunge(1),
munge(3),
munge_ctx(3),
munge_enum(3),
munge(7).
https://munge.googlecode.com/