1MUNGED(8) MUNGE Uid 'N' Gid Emporium MUNGED(8)
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7 munged - MUNGE daemon
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11 munged [OPTION]...
12
15 The munged daemon is responsible for authenticating local MUNGE clients
16 and servicing their credential encode & decode requests. All munged
17 daemons within a security realm share a secret key. This key is used
18 to protect the contents of a credential.
19 When a credential is created, munged embeds metadata within it includ‐
21 ing the effective UID and GID of the requesting client (as determined
22 by munged) and the current time (as determined by the local clock). It
23 then compresses the data, computes a message authentication code,
24 encrypts the data, and base64-encodes the result before returning the
25 credential to the client.
26 When a credential is validated, munged first checks the message authen‐
28 tication code to ensure the credential has not been subsequently
29 altered. Next, it checks the embedded UID/GID restrictions to deter‐
30 mine whether the requesting client is allowed to decode it. Then, it
31 checks the embedded encode time against the current time; if this dif‐
32 ference exceeds the embedded time-to-live, the credential has expired.
33 Finally, it checks whether this credential has been previously decoded
34 on this host; if so, the credential has been replayed. If all checks
35 pass, the credential metadata and payload are returned to the client.
36
39 -h, --help
40 Display a summary of the command-line options.
41 -L, --license
43 Display license information.
44 -V, --version
46 Display version information.
47 -f, --force
49 Force the daemon to run if at all possible. This overrides
50 warnings for an existing local domain socket, a lack of entropy
51 for the PRNG, and insecure file/directory permissions. Use with
52 caution as overriding these warnings can affect security.
53 -F, --foreground
55 Run the daemon in the foreground.
56 -M, --mlockall
58 Lock all current and future pages in the virtual memory address
59 space. Access to locked pages will never be delayed by a page
60 fault. This can improve performance and help the daemon remain
61 responsive when the system is under heavy memory pressure. This
62 typically requires root privileges or the CAP_IPC_LOCK capabil‐
63 ity.
64 -S, --socket path
66 Specify the local domain socket for communicating with clients.
67 --auth-server-dir directory
69 Specify an alternate directory in which the daemon will create
70 the pipe used to authenticate clients. The recommended permis‐
71 sions for this directory are 0711. This option is only valid on
72 platforms where client authentication is performed via a file-
73 descriptor passing mechanism.
74 --auth-client-dir directory
76 Specify an alternate directory in which clients will create the
77 file used to authenticate themselves to the daemon. The recom‐
78 mended permissions for this directory are 1733. This option is
79 only valid on platforms where client authentication is performed
80 via a file-descriptor passing mechanism.
81 --benchmark
83 Disable recurring timers in order to reduce some noise while
84 benchmarking. This affects the PRNG entropy pool, supplementary
85 group mapping, and credential replay hash. Do not enable this
86 option when running in production.
87 --group-check-mtime boolean
89 Specify whether the modification time of /etc/group should be
90 checked before updating the supplementary group membership map‐
91 ping. If this value is non-zero, the check will be enabled and
92 the mapping will not be updated unless the file has been modi‐
93 fied since the last update.
94 --group-update-time integer
96 Specify the number of seconds between updates to the supplemen‐
97 tary group membership mapping; this mapping is used when
98 restricting credentials by GID. A value of 0 causes it to be
99 computed initially but never updated (unless triggered by a
100 SIGHUP). A value of -1 causes it to be disabled.
101 --key-file path
103 Specify an alternate pathname to the key file.
104 --log-file path
106 Specify an alternate pathname to the log file.
107 --max-ttl integer
109 Specify the maximum allowable time-to-live value (in seconds)
110 for a credential. This setting has an upper-bound imposed by
111 the hard-coded MUNGE_MAXIMUM_TTL value. Reducing it will limit
112 the maximum growth of the credential replay cache. This is
113 viable if clocks within the MUNGE realm can be kept in sync with
114 minimal skew.
115 --num-threads integer
117 Specify the number of threads to spawn for processing credential
118 requests.
119 --pid-file path
121 Specify an alternate pathname for storing the Process ID of the
122 daemon.
123 --seed-file path
125 Specify an alternate pathname to the PRNG seed file.
126 --syslog
128 Redirect log messages to syslog when the daemon is running in
129 the background.
130 --trusted-group group
132 Specify the group name or GID of the "trusted group". This is
133 used for permission checks on a directory hierarchy. Directo‐
134 ries with group write permissions are allowed if they are owned
135 by the trusted group (or the sticky bit is set).
136
139 SIGHUP Immediately update the supplementary group membership mapping
140 instead of waiting for the next scheduled update; this mapping
141 is used when restricting credentials by GID.
142 SIGTERM
144 Terminate the daemon.
145
149 All clocks within a security realm must be kept in sync within the cre‐
150 dential time-to-live setting.
151 While munged prevents a given credential from being decoded on a par‐
153 ticular host more than once, nothing prevents a credential from being
154 decoded on multiple hosts within the security realm before it expires.
155
158 Chris Dunlap <cdunlap@llnl.gov>
159
162 Copyright (C) 2007-2017 Lawrence Livermore National Security, LLC.
163 Copyright (C) 2002-2007 The Regents of the University of California.
164 MUNGE is free software: you can redistribute it and/or modify it under
166 the terms of the GNU General Public License as published by the Free
167 Software Foundation, either version 3 of the License, or (at your
168 option) any later version.
169 Additionally for the MUNGE library (libmunge), you can redistribute it
171 and/or modify it under the terms of the GNU Lesser General Public
172 License as published by the Free Software Foundation, either version 3
173 of the License, or (at your option) any later version.
174
177 munge(1), remunge(1), unmunge(1), munge(3), munge_ctx(3),
178 munge_enum(3), munge(7).
179 https://dun.github.io/munge/
181munge-0.5.13 2017-09-26 MUNGED(8)