snmp4lptp: added snmp4lptp.8

Signed-off-by: Ethel Nilsson <ethel.nilsson@est.tech>

snmp4lptp.8

@@ -0,0 +1,119 @@
+.TH SNMP4LPTP 8 "September 2018" "linuxptp"
+.SH NAME
+snmp4lptp - SNMP sub agent
+
+.SH SYNOPSIS
+.B snmp4lptp
+[
+.BI \-f " config-file"
+] [
+.B \-m
+] [
+.B \-q
+] [
+.I long-options
+]
+
+.SH DESCRIPTION
+.B snmp4lptp
+is an implementation of a sub agent for handling SNMP requests on
+the device running ptp4l. Via the UDS port, the sub agent retrieves
+management information from ptp4l and translates the information to
+or from an SNMP-specific form. 
+
+.SH OPTIONS
+.TP
+.BI \-f " file"
+Specify the path to the \fBsnmp4lptp\fR configuration file.
+.TP
+.B \-h
+Display a help message.
+.TP
+.B \-m
+Print messages to the standard output.
+.TP
+.B \-q
+Don't send messages to the system logger.
+
+.SH LONG OPTIONS
+
+Each and every configuration file option (see below in sections
+.BR PROGRAM\ OPTIONS
+and
+.BR 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:
+
+.RS
+\f(CW\-\-transportSpecific 1   \-\-transportSpecific=1\fP
+.RE
+
+Option values given on the command line override values in the global
+section of the configuration file (which, in turn, overrides default
+values).
+
+.SH 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
+.BR [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.
+.BR [eth0]
+). Currently no port specific options other than default are considered.
+
+.SH PROGRAM OPTIONS
+.TP
+.B domainNumber
+The domain attribute of the local clock.
+The default is 0.
+.TP
+.B logging_level
+The maximum logging level of messages which should be printed.
+The default is 6 (LOG_INFO).
+.TP
+.B message_tag
+The tag which is added to all messages printed to the standard output or system
+log.
+The default is an empty string (which cannot be set in the configuration file
+as the option requires an argument).
+.TP
+.B use_syslog
+Print messages to the system log if enabled.
+The default is 1 (enabled).
+.TP
+.B verbose
+Print messages to the standard output if enabled.
+The default is 0 (disabled).
+.TP
+.B uds_address
+Specifies the address of the server's UNIX domain socket.
+The default is /var/run/ptp4l.
+
+.SH PORT OPTIONS
+.TP
+.B transportSpecific
+The transport specific field. Must be in the range 0 to 255.
+The default is 0.
+
+.SH WARNING
+
+Be cautious when the same configuration file is used for both ptp4l
+and snmp4lptp. 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 snmp4lptp is specified to a non-default value in
+the configuration file (e.g. for ptp4l), then this non-default value
+applies also for snmp4lptp. This might be not what is expected.
+
+To avoid securely these unexpected behaviour, different configuration files
+for ptp4l and snmp4lptp are recommended.
+
+.SH SEE ALSO
+.BR ptp4l (8)