Installing the Software
MUNGE requires either the Libgcrypt or OpenSSL cryptographic
library. Libgcrypt is licensed under the LGPL, whereas OpenSSL is licensed under dual original-BSD-style licenses. On some systems, the OpenSSL license is incompatible with
the GPL license used by MUNGE. While Libgcrypt offers a more compatible license, OpenSSL offers better performance. The selection of the cryptographic library can be specified at build time with the configure script's --with-crypto-lib option.
MUNGE includes bzip2 and zlib compression support if these
libraries are found when the software is built.
MUNGE can be installed using one of the following methods:
- Distributions:
MUNGE has been packaged for several distributions: Arch Linux, Debian, Fedora, Gentoo,
and Ubuntu.
- RPMs:
You can build binary RPMs from the tarball:
$ rpmbuild -tb --clean munge-x.y.z.tar.bz2
This will generate three binary RPMs: munge, munge-devel, and munge-libs. The munge RPM contains the daemon and client binaries. The munge-devel RPM contains a header file and static library for developing applications
using MUNGE. The munge-libs RPM contains a shared library for running applications using MUNGE.
The binary RPMs can be installed with rpm:
# rpm -ivh munge-x.y.z-1.i386.rpm munge-devel-x.y.z-1.i386.rpm munge-libs-x.y.z-1.i386.rpm
- Source:
Edit src/libcommon/munge_defs.h to customize values if necessary. To
compile the software, execute the following command; you may need to su to root in order to perform the "make
install":
$ ./configure --prefix=/usr --sysconfdir=/etc --localstatedir=/var && make
&& make install
Securing the Installation
On most platforms, the munged daemon does not require root privileges. If possible, you should run the daemon as a non-privileged user. This can be controlled by the init script as detailed in the Starting
the Daemon section below.
By default, the munged daemon uses the following system directories:
- /etc/munge/
This directory contains the daemon's secret key. The recommended permissions for it are 0700.
- /var/lib/munge/
This directory contains the daemon's PRNG seed file. It is also where the daemon creates pipes for authenticating clients via file-descriptor-passing. If the file-descriptor-passing authentication method is being
used, this directory must allow execute permissions for all; however, it should not expose read permissions. The recommended permissions for it are 0711.
- /var/log/munge/
This directory contains the daemon's log file. The recommended permissions for it are 0700.
- /var/run/munge/
This directory contains the Unix domain socket for clients to communicate with the daemon. It also contains the daemon's pid file. This directory must allow execute permissions for all. The recommended permissions
for it are 0755.
These directories must be owned by the user that the munged daemon will run as. They cannot allow write permissions for group or other (unless the sticky-bit is set). In addition, all of their parent directories
in the path on up to the root directory must be owned by either root or the user that the munged daemon will run as. None of them can allow write permissions for group or other (unless the sticky-bit is set).
Creating a Secret Key
A security realm encompasses a group of hosts having common users and groups. It is defined by a shared cryptographic key. Credentials are valid only within a security realm. All munged daemons within a security
realm must possess the same secret key.
By default, the secret key resides in /etc/munge/munge.key. This location
can be overridden on the munged command-line or via the init script as detailed in the Starting the Daemon section below.
You can create a secret key using a variety of methods:
- Wait around for some random data (recommended for the paranoid):
$ dd if=/dev/random bs=1 count=1024 >/etc/munge/munge.key
- Grab some pseudorandom data (recommended for the impatient):
$ dd if=/dev/urandom bs=1 count=1024 >/etc/munge/munge.key
- Enter the hash of a password:
$ echo -n "foo" | sha1sum | cut -d' ' -f1 >/etc/munge/munge.key
- Enter a password directly (not recommended):
$ echo "foo" >/etc/munge/munge.key
This file should be permissioned 0400 and owned by the user that the munged daemon will run as. Securely propagate this file (e.g., via ssh) to all other hosts within the same security realm.
Starting the Daemon
On each host within the security realm, invoke the daemon directly (/usr/sbin/munged)
or use the init script (/etc/init.d/munge start). The init script sources /etc/default/munge (found
on Debian-based systems) and /etc/sysconfig/munge (found on RedHat-based systems), if present, to set variables recognized
by the script.
The DAEMON_ARGS variable passes additional command-line options to the
daemon; for example, this can be used to override the location of the secret key (--key-file) or set the number of
worker threads (--num-threads). If the init script is invoked by root, the USER variable
causes the daemon to execute under the specified username; the daemon user is used by default.
Testing the Installation
The following steps can be performed to verify that the software has been properly installed and configured:
- Generate a credential on stdout:
$ munge -n
- Check if a credential can be locally decoded:
$ munge -n | unmunge
- Check if a credential can be remotely decoded:
$ munge -n | ssh somehost unmunge
- Run a quick benchmark:
$ remunge
If you encounter problems, check if the munged daemon is running (/etc/init.d/munge
status). Also, check the logfile (/var/log/munge/munged.log) or try running the daemon in the foreground (/usr/sbin/munged
--foreground). Some error conditions can be overridden by forcing the daemon (/usr/sbin/munged --force).
Using MUNGE
Applications written in C/C++ can use the interface provided by <munge.h>.
Scripts can invoke the munge and unmunge executables -- specify -h or --help for
usage information, or Read The Fine Manpages.