OneAgent non-privileged mode on Linux
By default, OneAgent is installed in the non-privileged mode, in which superuser privileges are used once to initiate the installation process.
OneAgent is then run under an unprivileged user, retaining the complete set of functionalities.
To install OneAgent in non-privileged mode, your system must meet the following requirements:
- The filesystem must support extended attributes.
- The system must have
libcap2installed. For example, the default Red Hat Enterprise Linux 5 installation doesn't have
- The filesystem must not be mounted as
- Linux Filesystem Capabilities must be enabled. For example, SUSE Linux Enterprise Server 11 has Linux Filesystem Capabilities disabled by default. For more information, see Non-privileged mode and Linux Filesystem Capabilities below.
See OneAgent security on Linux to learn about monitoring actions executed by OneAgent that require privileged access.
Privileges during installation
When run in non-privileged mode, the OneAgent installer requires superuser privileges to:
- Set file capabilities for OneAgent binaries located at
- Invoke the
oneagentservice script to start
- On systems with systemd, communicate with systemd daemon via d-bus to run the following commands:
systemctl <start|stop|enable|disable> oneagent.service
- On systems with SysV, execute
/sbin/chkconfigto add the
oneagentservice script to autostart or to remove it.
- Write to
Superuser privileges are dropped when the Dynatrace OneAgent service script is executed:
On systems with systemd, the unprivileged user is included in the service definition (unit file). The systemd daemon thus runs the OneAgent service script in unprivileged mode.
On systems with SysV, the privileges are dropped in the script when starting the OneAgent Watchdog process.
Linux System Capabilities
Dynatrace OneAgent Watchdog starts and runs all other processes under an unprivileged user without superuser access. OneAgent binaries leverage the following Linux System Capabilities.
|Binary||Linux System Capabilities|
|OneAgent Installer executed during auto-update|
Required only during initialization phase and is unconditionally dropped afterwards.
Kept in permitted set only and raised to the effective set when needed.
Only if ambient capabilities aren't supported.
Not used if auto-updates are disabled.
Only if ambient capabilities are supported.
Only for kernels 5.8 and newer, unless usage of unprivileged
Only on kernels older than 2.6.33.
Not started if automatic injection is disabled.
Linux Filesystem Capabilities are required to install OneAgent in non-privileged mode. SUSE Linux Enterprise Server 11 has Linux Filesystem Capabilities disabled by default. These capabilities might also be disabled in other supported Linux distributions or as the result of a custom configuration. The OneAgent installer prints the following message if Linux Filesystem Capabilities are disabled:
1Warning: Failed to enable non-privileged mode, kernel does not support file capabilities.
You can also check the kernel boot options to see if Linux Filesystem Capabilities are enabled. Run the following command to check your kernel boot options.
If you find
file_caps=1 in the output, your setup is fine.
To enable Linux Filesystem Capabilities, add
file_caps=1 to your kernel boot options. For example, on SUSE Linux Enterprise Server 11, use YaST, edit kernel boot options, add
file_caps=1, and reboot the machine.
Privileges during automatic updates and operation
The scope of privileges required by OneAgent depends on whether the kernel supports Linux ambient capabilities. As a general rule, kernel 4.3+ supports ambient capabilities. However, in the case of Red Hat Enterprise Linux, these may be supported in older kernel versions because of the Red Hat policy to backport patches. This makes ambient capabilities supported by kernel versions as old as 3.10.x.
During an automatic update, the installer starts under an unprivileged
dtuser with proper ambient capabilities set. OneAgent doesn't require root access to perform an automatic update.
Red Hat Enterprise Linux 7 has a too low
systemd (v219 instead of the required v221), and to be able to run automatic updates in non-privileged mode, we're temporarily elevating the privileges to run
systemctl <start|stop|enable|disable> oneagent.service.
How do I know if OneAgent operates in non-privileged mode?
The installer prints a message at the end of OneAgent installation. Depending on the kernel version and its support for ambient capabilities, you will see one of the following messages:
Non-privileged mode is enabled
The kernel supports ambient capabilities, the root access is not used for updates or operation.
Enabled non-privileged mode, but ambient capabilities are not supported by kernel
The kernel is within the minimum supported version, but due to non-supported ambient capabilities, OneAgent needs to elevate privileges in select cases, see above.
Failed to enable non-privileged mode
The kernel doesn't meet the minimum version requirements to enable non-privileged mode.