pmdanetcheck - Man Page

netcheck PMDA


pmdanetcheck is a Performance Co-Pilot (PCP) Performance Metrics Domain Agent (PMDA) which does basic network checks on the local host by using simple Python modules and, in some cases, external utilities such as ping(1).

pmdanetcheck loads and acts as a bridge for any number of configured, separate PCP netcheck PMDA Python modules running Python code or external programs. Existing Python modules and programs should be possible to be utilized with PCP netcheck PMDA modules with minimal effort.

Note that on SELinux enabled systems for pmdanetcheck to be able to use the ping(1) command the pcp group must be able to create ICMP Echo sockets; please make sure the group id for pcp is included in the range at /proc/sys/net/ipv4/ping_group_range and refer to icmp(7) for more details on this.


pmdanetcheck reads a mandatory ini-style configuration file:


This file must contain a [pmda] section. The following PMDA options are available (their default values are shown in parenthesis), options marked with asterisk (*) can be overridden in module-specific configuration sections:

modules (unset)

The pmdanetcheck PMDA reads module-specific configuration for each module listed in the comma-separated list of modules (mandatory).

hosts (DGW,DNS) *

A comma-separated list of hosts (optional) specifies the hosts to run the checks for. The special values DGW, DNS, NTP will be translated to the default gateway, nameservers listed in /etc/resolv.conf, and timeservers listed in /etc/chrony.conf, respectively, on PMDA startup.

background_check (True) *

A boolean value for background_check (optional) controls whether to run checks constantly in the background or only on demand. Refer to the default configuration file for more discussion about this.

check_hosts_parallel (True) *

check_hosts_parallel (optional) controls whether modules should check hosts one by one or in parallel.

check_interval (1m) *

check_interval (optional) specifies the time interval between two consecutive checks for hosts when checks are done in the background. Refer to PCPIntro(1) for a complete description of the syntax for the time interval.

align_interval (True) *

align_interval (optional) specifies whether to take the previous check duration into account when pausing between checks.

module_failure_fatal (True)

A boolean value for module_failure_fatal (optional) controls whether a module failing to initialize should cause the whole PMDA to abort (this is the default) or to start up with possibly remaining functional modules. Module configuration errors and internal errors (such as failing to register the provided PMNS metrics, see pmns(5)) will always cause the PMDA to fail to start.

For each module listed in modules a corresponding [module] section must be defined. Each [module] section can contain at least the following options (their default values are shown in parenthesis):

timeout (1)

Force a hard timeout (optional) for each individual network check operation.

debug (False)

Enable logging of internal debug messages (rarely used).

The module-specific options modules accept are described in the default configuration file.

Modules expect basic network functionality to be present on the system, for example the localhost address being reachable.


To install, the following must be done as root:

# cd $PCP_PMDAS_DIR/netcheck
# ./Install

To uninstall, the following must be done as root:

# cd $PCP_PMDAS_DIR/netcheck
# ./Remove

pmdanetcheck is launched by pmcd(1) and should never be executed directly. The Install and Remove scripts notify pmcd(1) when the agent is installed or removed.

In case module_failure_fatal is set to False, the PMDA installation will be considered successful if some (but not all) configured modules fail to load, in such cases metrics provided by the failing modules will not be available. The pmdanetcheck agent log file (see below) will contain detailed information about activation of each module.

Modules will provide real values only after having collected data. For example, for the ping module the metric value is the exit value of the ping(1) command and for ping_latency the average packet latency as reported by ping(1). For metrics indicating status, 0 denotes success. In case a check has not finished yet its metric value is -1. If a check was terminated during execution due to timeout the value is -2.



configuration file for the pmdanetcheck agent


PCP netcheck PMDA Python modules for the pmdanetcheck agent


installation script for the pmdanetcheck agent


undo installation script for the pmdanetcheck agent


default log file for messages from the pmdanetcheck agent

Note that the usual/default value for $PCP_PMDAS_DIR is /var/lib/pcp/pmdas and the default for $PCP_LOG_DIR is /var/log/pcp but these settings are platform dependent.

PCP Environment

Environment variables with the prefix PCP_ are used to parameterize the file and directory names used by PCP. On each installation, the file /etc/pcp.conf contains the local values for these variables. The $PCP_CONF variable may be used to specify an alternative configuration file, as described in pcp.conf(5).

See Also

PCPIntro(1), ping(1), pmcd(1), getaddrinfo(3), resolver(3), gai.conf(5), resolv.conf(5), resolver(5), icmp(7) and ip(8).


PCP Performance Co-Pilot