nsm(8): NetSync Monitor client

SYNOPSIS

nsm [ -f config ] [ -i interface ] [ long-options ] [ command ] …

DESCRIPTION

nsm is a program which implements a NetSync Monitor (NSM) client. NSM is an extension to the Precision Time Protocol (PTP), which enables a client to measure the offset of its clock against any PTP clock in the network which supports NSM. It uses unicast messages, but unlike PTP in the unicast mode it does not require the server to keep any state specific to the client. It is particularly useful for monitoring.

The program reads commands from the standard input or from the command line.

COMMANDS

NSM address: Send a NetSync Monitor request to the specified network address (IPv4 or MAC) and print the measured offset with the response.
help: Display a help message.

OPTIONS

-f config: Read configuration from the specified file. No configuration file is read by default.
-i interface: Specify the network interface.
-h: Display a help message.
-v: Print the software version and exit.

LONG OPTIONS

Each and every configuration file option (see below in sections PROGRAM OPTIONS and PORT OPTIONS) may also appear as a “long” style command line argument. For example, the transportSpecific option may be set using either of these two forms:

--transportSpecific 1

--transportSpecific=1

Option values given on the command line override values in the global section of the configuration file (which, in turn, overrides default values).

CONFIGURATION FILE

The configuration file is divided into sections. Each section starts with a line containing its name enclosed in brackets and it follows with settings. Each setting is placed on a separate line, it contains the name of the option and the value separated by whitespace characters. Empty lines and lines starting with # are ignored.

The global section (indicated as [global]) sets the global program options as well as the default port specific options. Other sections are port specific sections and they override the default port options. The name of the section is the name of the configured port (e.g. [eth0]).

PORT OPTIONS

active_key_id: Used in conjunction with spp and sa_file directives to specify which key from the spp defined Security Association should be used for outbound icv calculations. All Security Assocations are read from the file specified by sa_file. Requires spp and sa_file directives. Must be in the range of 1 to 2^{^32}-1, inclusive. The default is 0 (disabled).
delayAsymmetry: The time difference in nanoseconds of the transmit and receive paths. This value should be positive when the master-to-slave propagation time is longer and negative when the slave-to-master time is longer. The default is 0 nanoseconds.
network_transport: Select the network transport. Possible values are UDPv4 and L2. The default is UDPv4.
spp: Specifies the Security Parameters Pointer of the desired Security Association to be used for Authentication TLV support for a given port. Any port with an assigned spp will attach Authentication TLVs to all outbound messages and check for Authentication TLVs on all inbound messages in accordance to the corresponding security association sourced via the sa_file directive. Outbound Authentication TLVs are generated using the key specified by active_key_id. Not compatible with one step ports or advertised versions less then PTPv2.1. Requires sa_file and active_key_id directives. Must be in the range of 0 to 255, inclusive. The default is -1 (disabled).
transportSpecific: The transport specific field. Must be in the range 0 to 255. The default is 0.

PROGRAM OPTIONS

domainNumber: The domain attribute of the local clock. The default is 0.
sa_file: Specifies the location of the file containing Security Associations used for immediate security processing of the Authentication TLV in support of the optional security mechanism defined in ieee1588-2019 ch 14.16. See SECURITY ASSOCIATION OPTIONS for information on how this file should be formatted. spp and active_key_id should be specifed for each port to indicate which Security Association from the sa_file should be used. The default is an empty string.
time_stamping: The time stamping method. The allowed values are hardware, software, and legacy. The default is hardware.

WARNING

Be cautious when the same configuration file is used for both ptp4l and nsm. Keep in mind that values specified in the configuration file take precedence over their default values. If a certain option which is common to ptp4l and nsm is specified to a non-default value in the configuration file (e.g. for ptp4l), then this non-default value applies also for nsm. This might be not what is expected.

To avoid securely this unexpected behaviour, different configuration files for ptp4l and nsm are recommended.