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snmptrapd.conf - configuration file for the Net-SNMP notification receiver
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is the configuration file(s) which define how the Net-SNMP SNMP notification
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receiver (trap daemon) operates when it receives a notification.
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These files may contain any of the directives found in the
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section below. This file is not required for the daemon to operate,
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receive, or report traps. It is used solely as a method of providing
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extensibility to the trap daemon.
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First, make sure you have read the
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The Net-SNMP notification receiver (trap daemon) uses one or more
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configuration files to control its operation and how incoming traps
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(and INFORM requests) should be processed.
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This file (\fBsnmptrapd.conf\fR) can be located in
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one of several locations, as described in the
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describes how the Net-SNMP configuration files operate, where they
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are located and how they all work together.
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would accept all incoming notifications, and log them automatically
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(even if no explicit configuration was provided).
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Starting with release 5.3, access control checks will be applied to
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incoming notifications. If
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is run without a suitable configuration file (or equivalent access
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control settings), then such traps \fBWILL NOT\fR
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See the section \fBACCESS CONTROL\fR for more details.
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As with the agent configuration, the
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directives can be divided into four distinct groups.
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.IP "snmpTrapdAddr [<transport-specifier>:]<transport-address>[,...]"
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defines a list of listening addresses, on which to receive
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incoming SNMP notifications.
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.B LISTENING ADDRESSES
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manual page for more information about the format of listening
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The default behaviour is to
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listen on UDP port 162 on all IPv4 interfaces.
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.IP "doNotRetainNotificationLogs yes"
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disables support for the NOTIFICATION-LOG-MIB.
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Normally the snmptrapd program keeps a record of the traps
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received, which can be retrieved by querying
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the \fCnlmLogTable\fR and \fCnlmLogvariableTable\fR tables.
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This directive can be used to suppress this behaviour.
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manual page and the NOTIFICATION-LOG-MIB for details.
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.IP "doNotLogTraps yes"
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disables the logging of notifications altogether.
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This is useful if the \fBsnmptrapd\fR application should
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only run traphandle hooks and should not log traps to any location.
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do not fork from the calling shell.
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defines a file in which to store the process ID of the
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notification receiver. By default, this ID is not saved.
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Starting with release 5.3, it is necessary to explicitly specify
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who is authorised to send traps and informs to the notification
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receiver (and what types of processing these are allowed to trigger).
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This uses an extension of the VACM model, used in the main SNMP agent.
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There are currently three types of processing that can be specified:
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log the details of the notification - either in a specified file,
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to standard output (or stderr), or via \fIsyslog\fR (or similar).
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pass the details of the trap to a specified handler program, including
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forward the trap to another notification receiver.
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In the following directives, \fITYPES\fR will be a (comma-separated)
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list of one or more of these tokens. Most commonly, this will
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typically be \fIlog,execute,net\fR to cover any style of processing
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for a particular category of notification. But it is perfectly
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possible (even desirable) to limit certain notification sources to
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selected processing only.
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.IP "authCommunity TYPES COMMUNITY [SOURCE [OID | -v VIEW ]]"
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authorises traps (and SNMPv2c INFORM requests) with the specified
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community to trigger the types of processing listed.
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By default, this will allow any notification using this community
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to be processed. The SOURCE field can be used to specify that the
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configuration should only apply to notifications received from
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particular sources - see \fIsnmpd.conf(5)\fR for more details.
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.IP "authUser TYPES [-s MODEL] USER [LEVEL [OID | -v VIEW ]]"
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authorises SNMPv3 notifications with the specified
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user to trigger the types of processing listed.
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By default, this will accept authenticated requests.
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(\fIauthNoPriv\fR or \fIauthPriv\fR). The LEVEL field can
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be used to allow unauthenticated notifications (\fInoauth\fR),
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or to require encryption (\fIpriv\fR), just as for the SNMP agent.
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With both of these directives, the OID (or \fI-v VIEW\fR) field
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can be used to retrict this configuration to the processing of
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particular notifications.
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Unlike the VACM processing described in RFC 3415, this view is
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\fBonly\fR matched against the \fCsnmpTrapOID\fR value of the
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incoming notification. It is not applied to the payload varbinds
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held within that notification.
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.IP "authGroup TYPES [-s MODEL] GROUP [LEVEL [OID | -v VIEW ]]"
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.IP "authAccess TYPES [-s MODEL] GROUP VIEW [LEVEL [CONTEXT]]"
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.IP "setAccess GROUP CONTEXT MODEL LEVEL PREFIX VIEW TYPES"
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authorise notifications in the specified GROUP
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(configured using the \fIgroup\fR directive)
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to trigger the types of processing listed.
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See \fIsnmpd.conf(5)\fR for more details.
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.IP "createUser username (MD5|SHA) authpassphrase [DES|AES]"
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manual page for a description of how to create SNMPv3 users. This
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is roughly the same, but the file name changes to snmptrapd.conf from
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.IP "disableAuthorization yes"
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will disable the above access control checks, and revert to the
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previous behaviour of accepting all incoming notifications.
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.\" XXX - Explain why this is a Bad Idea
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specify the format used to display SNMPv1 TRAPs and SNMPv2
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notifications respectively. Note that SNMPv2c and SNMPv3
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both use the same SNMPv2 PDU format.
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for the layout characters available.
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.IP "ignoreAuthFailure yes"
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instructs the receiver to ignore \fIauthenticationFailure\fR traps.
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This currently only affects the logging of such notifications.
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\fIauthenticationFailure\fR traps will still be passed to trap
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handler scripts, and forwarded to other notification receivers.
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This behaviour should not be relied on, as it is likely
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to change in future versions.
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.IP "logOption string"
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specifies where notifications should be logged - to standard
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output, standard error, a specified file or via \fIsyslog\fR.
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See the section LOGGING OPTIONS in the
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\fIsnmpcmd(1)\fR manual page for details.
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.IP "outputOption string"
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specifies various characteristics of how OIDs and other values
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See the section OUTPUT OPTIONS in the
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\fIsnmpcmd(1)\fR manual page for details.
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.IP "printEventNumbers yes"
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enables specialised logging of event-related notifications from
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the (long obsolete) M2M-MIB.
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.\" XXX - CHECK EXACTLY WHICH TRAPS
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.\" XXX - THIS FEELS OBSOLETE TO ME!
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.SH NOTIFICATION PROCESSING
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As well as logging incoming notifications, they can also
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be forwarded on to another notification receiver, or passed
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to an external program for specialised processing.
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.IP "traphandle OID|default PROGRAM [ARGS ...]"
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configuration directive configures the snmptrapd program to launch an
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external program any time it receives a trap matching the OID token.
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If the OID token is the word
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then any trap not matching any other trap handler will call this
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The program is fed details about the trap to its standard input, in the
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following format, one entry per line:
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invokes the specified program (with the given arguments) whenever a
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notification is received with a \fCsnmpTrapOID\fR value matching the
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OID token. If this field is \fIdefault\fR then the program will be
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invoked for any notification not matching another (OID specific)
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\fItraphandle\fR entry.
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An SNMPv1 trap will be converted to an equivalent SNMPv2-style
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notification (following RFC 2576), before selecting the trap
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handler(s) to call. This will affect both the OIDs listed
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in \fItraphandle\fR entries, and the format of the data passed
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to the trap handler program.
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The program is fed details about the notification to its standard input,
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in the following format, one entry per line:
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The name of the host in question that sent the trap, as determined by
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The name of the host that sent the notification, as determined by
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.IR gethostbyaddr(3) .
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The IP address of the host that sent the trap.
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The IP address of the host that sent the notification.
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.\" XXX - What about non-IPv4 transports?
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A list of variable bindings that describe the trap and the variables
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enclosed in it. The first token on the line, up until the space, in
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the OID and the remainder of the line is its value. The first OID
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should be the system.sysUpTime.0 OID, and the second should be
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the ...snmpTrap.snmpTrapOID.0 OID. The remainder of the OIDs, with the
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possible exception of the last one, are the variable bindings
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contained within the trap. For SNMPv1 traps, the very last OID will
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be the ...snmpTrap.snmpTrapEnterprise OID and its value. Essentially,
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SNMPv1 traps have been converted to the SNMPv2 trap PDU type by the
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method described in the SNMPv1/SNMPv2/SNMPv3 coexistence document (RFC2576).
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A list of variable bindings describing the contents of the notification,
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one per line. The first token on each line (up until a space) is the
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OID of the varind, and the remainder of the line is its value.
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The format of both of these are controlled by the \fIoutputOption\fR
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directive (or similar configuration).
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The first OID should always be \fCSNMPv2-MIB::sysUpTime.0\fR,
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and the second should be \fCSNMPv2-MIB::snmpTrapOID.0\fR.
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The remaining lines will contain the payload varbind list.
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For SNMPv1 traps, the final OID will be \fCSNMPv2-MIB::snmpTrapEnterprise.0\fR.
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A traptoemail script has been included in the Net-SNMP package that
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can be used as a trap handle directive:
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A \fBtraptoemail\fR script has been included in the Net-SNMP package that
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can be used within a \fItraphandle\fR directive:
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traphandle default /usr/bin/perl BINDIR/traptoemail -s mysmtp.somewhere.com -f admin@somewhere.com me@somewhere.com
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.IP "snmptrapdaddr [<transport-specifier>:]<transport-address>[,...]"
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Makes the agent listen on the specified comma-separated list of
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listening addresses instead of the default behaviour, which is to
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listen on UDP port 162 on all IPv4 interfaces. See the section
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.B LISTENING ADDRESSES
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manual page for more information about the format of listening
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.IP "dontRetainLogs true"
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Turns off the support for the NOTIFICATION-LOG-MIB and thus doesn't
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retain logged traps. Normally the snmptrapd program keeps a certain
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number of traps around in memory so they can be retrieved via querying
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the nlmLogTable and nlmLogvariableTable tables.
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manual page and the NOTIFICATION-LOG-MIB for details.
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.IP "createUser username (MD5|SHA) authpassphrase [DES|AES]"
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manual page for a description of how to create SNMPv3 users. It's
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roughly the same, but the file name changes to snmptrapd.conf from
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The format used to print a SNMPv1 TRAP message. See
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for the layout characters available.
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The format used to print a SNMPv2 TRAP2 or INFORM message (note that
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the SNMPv3 protocol uses SNMPv2 style TRAPs and INFORMs).
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.IP "forward OID|default DESTINATION"
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Forwards traps received to DESTINATION if they match the notification
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type indicated by OID (or the word default forwards them all).
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.IP "ignoreAuthFailure (1|yes|true|0|no|false)"
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Whether or not ignore authenticationFailure traps.
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.IP "doNotLogTraps (1|yes|true|0|no|false)"
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Whether or not to log traps. This is
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useful if you want the snmptrapd application to only run traphandle
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hooks and not to log any traps to any location.
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.IP "logOption string"
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Specify where logging output should be directed (standard error or
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output, to a file or via syslog). See LOGGING OPTIONS in
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snmpcmd(1) for details.
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.IP "outputOption string"
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The same output formatting (-O) options as the other Net-SNMP
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commands. See the section OUTPUT OPTIONS in the snmpcmd(1)
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.IP "printEventNumbers (1|yes|true|0|no|false)"
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Whether or not to print event numbers (rising/falling alarm etc.).
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.IP "doNotFork (1|yes|true|0|no|false)"
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Whether or not to fork from the calling shell.
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What file to store the process id in
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forwards notifications that match the specified OID
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to another receiver listening on DESTINATION.
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The interpretation of OID (and \fIdefault\fR) is the same
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as for the \fItraphandle\fR directive).
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.B LISTENING ADDRESSES
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manual page for more information about the format of listening
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The daemon blocks on the executing traphandle commands. (This should
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The daemon blocks while executing the \fItraphandle\fR commands.
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be fixed in the future with an appropriate signal catch and wait()
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All directives listed with a value of "yes" actually accept a range
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of boolean values. These will accept any of \fI1\fR, \fIyes\fR or
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\fItrue\fR to enable the corresponding behaviour,
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or any of \fI0\fR, \fIno\fR or \fIfalse\fR to disable it.
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The default in each case is for the feature to be turned off, so these
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directives are typically only used to enable the appropriate behaviour.
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SYSCONFDIR/snmp/snmptrapd.conf
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man/snmptrapd.conf.5.def
