snmpd.conf man page on SuSE

Man page or keyword search:  
man Server   14857 pages
apropos Keyword Search (all sections)
Output format
SuSE logo
[printable version]

SNMPD.CONF(5)			   Net-SNMP			 SNMPD.CONF(5)

NAME
       snmpd.conf - configuration file for the Net-SNMP SNMP agent

DESCRIPTION
       The  Net-SNMP agent uses one or more configuration files to control its
       operation  and  the  management	information  provided.	 These	 files
       (snmpd.conf  and	 snmpd.local.conf)  can	 be  located in one of several
       locations, as described in the snmp_config(5) manual page.

       The (perl) application snmpconf can be used to  generate	 configuration
       files for the most common agent requirements.  See the snmpconf(1) man‐
       ual page for more information, or try running the command:

	      snmpconf -g basic_setup

       There are a large number of directives that can be specified, but these
       mostly fall into four distinct categories:

       ·      those controlling who can access the agent

       ·      those configuring the information that is supplied by the agent

       ·      those controlling active monitoring of the local system

       ·      those concerned with extending the functionality of the agent.

       Some directives don't fall naturally into any of these four categories,
       but this covers the majority of the contents of	a  typical  snmpd.conf
       file.   A full list of recognised directives can be obtained by running
       the command:

	      snmpd -H

AGENT BEHAVIOUR
       Although most configuration  directives	are  concerned	with  the  MIB
       information  supplied  by  the agent, there are a handful of directives
       that control the behaviour of snmpd considered simply as a daemon  pro‐
       viding a network service.

       agentaddress [<transport-specifier>:]<transport-address>[,...]
	      defines  a  list	of  listening  addresses,  on which to receive
	      incoming SNMP requests.  See the section LISTENING ADDRESSES  in
	      the  snmpd(8)  manual page for more information about the format
	      of listening addresses.

	      The default behaviour is to listen on UDP port 161 on  all  IPv4
	      interfaces.

       agentgroup {GROUP|#GID}
	      changes  to  the	specified  group  after	 opening the listening
	      port(s).	This may refer to  a  group  by	 name  (GROUP),	 or  a
	      numeric group ID starting with '#' (#GID).

       agentuser {USER|#UID}
	      changes  to  the	specified  user	 after	opening	 the listening
	      port(s).	This may refer to a user by name (USER), or a  numeric
	      user ID starting with '#' (#UID).

       leave_pidfile yes
	      instructs	 the  agent  to	 not  remove its pid file on shutdown.
	      Equivalent to specifying "-U" on the command line.

       maxGetbulkRepeats NUM
	      Sets the maximum number of responses allowed for a single	 vari‐
	      able  in	a getbulk request.  Set to 0 to enable the default and
	      set it to -1 to enable unlimited.	 Because memory	 is  allocated
	      ahead  of time, sitting this to unlimited is not considered safe
	      if your user population can not be  trusted.   A	repeat	number
	      greater than this will be truncated to this value.

	      This is set by default to -1.

       maxGetbulkResponses NUM
	      Sets  the	 maximum  number  of  responses	 allowed for a getbulk
	      request.	This is set by default to 100.	Set to 0 to enable the
	      default and set it to -1 to enable unlimited.  Because memory is
	      allocated ahead of time, sitting this to unlimited is  not  con‐
	      sidered safe if your user population can not be trusted.

	      In general, the total number of responses will not be allowed to
	      exceed the  maxGetbulkResponses  number  and  the	 total	number
	      returned	will be an integer multiple of the number of variables
	      requested times the calculated number of repeats	allow  to  fit
	      below this number.

	      Also not that processing of maxGetbulkRepeats is handled first.

   SNMPv3 Configuration
       SNMPv3  requires	 an SNMP agent to define a unique "engine ID" in order
       to respond to SNMPv3 requests.  This ID	will  normally	be  determined
       automatically,	using	two  reasonably	 non-predictable  values  -  a
       (pseudo-)random number and the current uptime in seconds. This  is  the
       recommended  approach.  However	the  capacity  exists  to  define  the
       engineID in other ways:

       engineID STRING
	      specifies that the engineID should be built from the given  text
	      STRING.

       engineIDType 1|2|3
	      specifies	 that  the  engineID  should  be  built	 from the IPv4
	      address (1), IPv6 address (2) or MAC  address  (3).   Note  that
	      changing	the  IP	 address  (or  switching the network interface
	      card) may cause problems.

       engineIDNic INTERFACE
	      defines which interface to use when determining the MAC address.
	      If  engineIDType	3 is not specified, then this directive has no
	      effect.

	      The default is to use eth0.

ACCESS CONTROL
       snmpd supports the View-Based Access Control Model (VACM) as defined in
       RFC  2575,  to control who can retrieve or update information.  To this
       end, it recognizes  various  directives	relating  to  access  control.
       These fall into four basic groups.

   SNMPv3 Users
       createUser  [-e	ENGINEID]  username (MD5|SHA) authpassphrase [DES|AES]
       [privpassphrase]

	      MD5 and SHA are the authentication types to use.	 DES  and  AES
	      are  the privacy protocols to use.  If the privacy passphrase is
	      not specified, it is assumed to be the same as  the  authentica‐
	      tion  passphrase.	  Note	that the users created will be useless
	      unless they are also added to the	 VACM  access  control	tables
	      described above.

	      SHA  authentication  and	DES/AES	 privacy require OpenSSL to be
	      installed and the agent to be built with OpenSSL	support.   MD5
	      authentication may be used without OpenSSL.

	      Warning: the minimum pass phrase length is 8 characters.

	      SNMPv3 users can be created at runtime using the snmpusm(1) com‐
	      mand.

	      Instead of figuring out how to use this directive and  where  to
	      put   it	 (see  below),	just  run  "net-snmp-config  --create-
	      snmpv3-user" instead, which will add one of these lines  to  the
	      right place.

	      This   directive	 should	  be  placed  into  the	 /var/lib/net-
	      snmp/snmpd.conf file instead of the other normal locations.  The
	      reason  is  that	the information is read from the file and then
	      the line is removed (eliminating the storage of the master pass‐
	      word  for	 that  user) and replaced with the key that is derived
	      from it.	This key is a localized key, so that if it  is	stolen
	      it  can  not be used to access other agents.  If the password is
	      stolen, however, it can be.

	      If you need to localize the user to a particular EngineID	 (this
	      is  useful  mostly  in the similar snmptrapd.conf file), you can
	      use the -e argument to specify an EngineID as a hex  value  (EG,
	      "0x01020304").

	      If  you  want  to	 generate either your master or localized keys
	      directly, replace the given password with a hexstring (preceeded
	      by  a  "0x")  and	 precede  the  hex  string by a -m or -l token
	      (respectively).  EGs:

	      [these keys are *not* secure but are easy to visually parse for
	      counting purposes.  Please generate random keys instead of using
	      these examples]

	      createUser myuser SHA -l 0x0001020304050607080900010203040506070809 AES -l 0x00010203040506070809000102030405
	      createUser myuser SHA -m 0x0001020304050607080900010203040506070809 AES -m 0x0001020304050607080900010203040506070809

	      Due to the way localization happens, localized privacy keys  are
	      expected	to be the length needed by the algorithm (128 bits for
	      all supported algorithms).  Master encryption keys, though, need
	      to  be  the  length required by the authentication algorithm not
	      the length required by the encrypting algorithm (MD5: 16	bytes,
	      SHA: 20 bytes).

   Traditional Access Control
       Most  simple  access  control  requirements  can be specified using the
       directives rouser/rwuser (for SNMPv3) or	 rocommunity/rwcommunity  (for
       SNMPv1 or SNMPv2c).

       rouser USER [noauth|auth|priv [OID | -V VIEW [CONTEXT]]]

       rwuser USER [noauth|auth|priv [OID | -V VIEW [CONTEXT]]]
	      specify  an  SNMPv3 user that will be allowed read-only (GET and
	      GETNEXT) or read-write (GET, GETNEXT  and	 SET)  access  respec‐
	      tively.	By  default,  this will provide access to the full OID
	      tree for authenticated (including	 encrypted)  SNMPv3  requests,
	      using  the  default  context.   An  alternative minimum security
	      level can be specified using noauth  (to	allow  unauthenticated
	      requests),  or  priv  (to	 enforce  use of encryption).  The OID
	      field restricts access for that user to the  subtree  rooted  at
	      the  given OID, or the named view.  An optional context can also
	      be specified, or "context*" to denote a context prefix.	If  no
	      context  field  is  specified  (or  the  token "*" is used), the
	      directive will match all possible contexts.

       rocommunity COMMUNITY [SOURCE [OID | -V VIEW [CONTEXT]]]

       rwcommunity COMMUNITY [SOURCE [OID | -V VIEW [CONTEXT]]]
	      specify an SNMPv1 or SNMPv2c  community  that  will  be  allowed
	      read-only (GET and GETNEXT) or read-write (GET, GETNEXT and SET)
	      access respectively.  By default, this will  provide  access  to
	      the  full	 OID  tree for such requests, regardless of where they
	      were sent from. The SOURCE token can be used to restrict	access
	      to  requests  from the specified system(s) - see com2sec for the
	      full details.  The OID field restricts access for that community
	      to the subtree rooted at the given OID, or named view.  Contexts
	      are typically less relevant to  community-based  SNMP  versions,
	      but the same behaviour applies here.

       rocommunity6 COMMUNITY [SOURCE [OID | -V VIEW [CONTEXT]]]

       rwcommunity6 COMMUNITY [SOURCE [OID | -V VIEW [CONTEXT]]]
	      are  directives relating to requests received using IPv6 (if the
	      agent supports such transport domains).  The  interpretation  of
	      the SOURCE, OID, VIEW and CONTEXT tokens are exactly the same as
	      for the IPv4 versions.

       In each case, only one directive should be specified for a given SNMPv3
       user,  or  community  string.   It  is  not appropriate to specify both
       rouser and rwuser directives referring to  the  same  SNMPv3  user  (or
       equivalent  community  settings). The rwuser directive provides all the
       access of rouser (as well as allowing SET  support).   The  same	 holds
       true for the community-based directives.

       More  complex  access  requirements (such as access to two or more dis‐
       tinct OID subtrees, or different views for GET and SET requests) should
       use  one	 of the other access control mechanisms.  Note that if several
       distinct communities or SNMPv3 users need to be granted the same	 level
       of access, it would also be more efficient to use the main VACM config‐
       uration directives.

   VACM Configuration
       The full flexibility of the VACM is available using four	 configuration
       directives  -  com2sec,	group,	view and access.  These provide direct
       configuration of the underlying VACM tables.

       com2sec	[-Cn CONTEXT] SECNAME SOURCE COMMUNITY

       com2sec6 [-Cn CONTEXT] SECNAME SOURCE COMMUNITY
	      map an SNMPv1 or SNMPv2c community string to a security  name  -
	      either  from a particular range of source addresses, or globally
	      ("default").  A restricted source can either be a specific host‐
	      name  (or	 address),  or a subnet - represented as IP/MASK (e.g.
	      10.10.10.0/255.255.255.0), or IP/BITS (e.g.  10.10.10.0/24),  or
	      the IPv6 equivalents.

	      The  same	 community string can be specified in several separate
	      directives (presumably with different source  tokens),  and  the
	      first  source/community  combination  that  matches the incoming
	      request will be selected.	 Various source/community combinations
	      can also map to the same security name.

	      If a CONTEXT is specified (using -Cn), the community string will
	      be mapped to a security name in the named SNMPv3 context. Other‐
	      wise the default context ("") will be used.

       com2secunix [-Cn CONTEXT] SECNAME SOCKPATH COMMUNITY
	      is the Unix domain sockets version of com2sec.

       group GROUP {v1|v2c|usm} SECNAME
	      maps  a  security	 name (in the specified security model) into a
	      named group.  Several group  directives  can  specify  the  same
	      group name, allowing a single access setting to apply to several
	      users and/or community strings.

	      Note that groups must be set up for the two community-based mod‐
	      els separately - a single com2sec (or equivalent) directive will
	      typically be accompanied by two group directives.

       view VNAME TYPE OID [MASK]
	      defines a named "view" - a subset of the overall OID tree.  This
	      is  most	commonly a single subtree, but several view directives
	      can be given with the same view name (VNAME), to build up a more
	      complex	collection  of	OIDs.	TYPE  is  either  included  or
	      excluded, which can again define a more  complex	view  (e.g  by
	      excluding certain sensitive objects from an otherwise accessible
	      subtree).

	      MASK is a list of hex octets (optionally	separated  by  '.'  or
	      ':')  with  the  set bits indicating which subidentifiers in the
	      view OID to match against.  If not specified, this  defaults  to
	      matching	the OID exactly (all bits set), thus defining a simple
	      OID subtree.  So:
		     view iso1 included .iso  0xf0
		     view iso2 included .iso
		     view iso3 included .iso.org.dod.mgmt  0xf0

	      would all define the  same  view,	 covering  the	whole  of  the
	      'iso(1)' subtree (with the third example ignoring the subidenti‐
	      fiers not covered by the mask).

	      More usefully, the mask can be used to define a view covering  a
	      particular  row  (or  rows)  in a table, by matching against the
	      appropriate table index value, but skipping the column  subiden‐
	      tifier:

		     view ifRow4 included .1.3.6.1.2.1.2.2.1.0.4  0xff:a0

	      Note that a mask longer than 8 bits must use ':' to separate the
	      individual octets.

       access GROUP CONTEXT {any|v1|v2c|usm} LEVEL PREFX READ WRITE NOTIFY
	      maps from a group of users/communities (with a particular	 secu‐
	      rity  model  and	minimum security level, and in a specific con‐
	      text) to one of three views, depending on the request being pro‐
	      cessed.

	      LEVEL is one of noauth, auth, or priv.  PREFX specifies how CON‐
	      TEXT should be matched  against  the  context  of	 the  incoming
	      request,	either exact or prefix.	 READ, WRITE and NOTIFY speci‐
	      fies the view to be used for GET*, SET and TRAP/INFORM  requests
	      (althought  the  NOTIFY  view is not currently used).  For v1 or
	      v2c access, LEVEL will need to be noauth.

   Typed-View Configuration
       The final group of directives extend the	 VACM  approach	 into  a  more
       flexible	 mechanism,  which  can	 be  applied  to  other access control
       requirements. Rather than the fixed three views of  the	standard  VACM
       mechanism,  this can be used to configure various different view types.
       As far as the main SNMP agent is concerned, the two main view types are
       read  and  write, corresponding to the READ and WRITE views of the main
       access directive.  See the 'snmptrapd.conf(5)' man page for  discussion
       of other view types.

       authcommunity TYPES  COMMUNITY	[SOURCE [OID | -V VIEW [CONTEXT]]]
	      is  an  alternative  to  the rocommunity/rwcommunity directives.
	      TYPES will usually be read or read,write respectively.  The view
	      specification  can  either  be  an OID subtree (as before), or a
	      named view (defined using the view directive) for greater flexi‐
	      bility.	If this is omitted, then access will be allowed to the
	      full OID tree.  If CONTEXT is specified,	access	is  configured
	      within  this SNMPv3 context.  Otherwise the default context ("")
	      is used.

       authuser	  TYPES [-s MODEL] USER	 [LEVEL [OID | -V VIEW [CONTEXT]]]
	      is an alternative to the rouser/rwuser directives.   The	fields
	      TYPES,  OID, VIEW and CONTEXT have the same meaning as for auth‐
	      community.

       authgroup  TYPES [-s MODEL] GROUP [LEVEL [OID | -V VIEW [CONTEXT]]]
	      is a companion to the authuser directive, specifying access  for
	      a particular group (defined using the group directive as usual).
	      Both authuser and authgroup default to authenticated requests  -
	      LEVEL can also be specified as noauth or priv to allow unauthen‐
	      ticated requests,	 or  require  encryption  respectively.	  Both
	      authuser	and  authgroup	directives also default to configuring
	      access for SNMPv3/USM requests - use the '-s' flag to specify an
	      alternative  security model (using the same values as for access
	      above).

       authaccess TYPES [-s MODEL] GROUP VIEW [LEVEL [CONTEXT]]
	      also configures the access for a	particular  group,  specifying
	      the  name	 and type of view to apply. The MODEL and LEVEL fields
	      are interpreted in the same way as for authgroup.	 If CONTEXT is
	      specified,  access  is configured within this SNMPv3 context (or
	      contexts with this prefix if the CONTEXT field ends  with	 '*').
	      Otherwise the default context ("") is used.

       setaccess GROUP CONTEXT MODEL LEVEL PREFIX VIEW TYPES
	      is  a  direct equivalent to the original access directive, typi‐
	      cally listing the view types as read or read,write as  appropri‐
	      ate.  (or see 'snmptrapd.conf(5)' for other possibilities).  All
	      other fields have the same interpretation as with access.

SYSTEM INFORMATION
       Most of the information reported by the	Net-SNMP  agent	 is  retrieved
       from  the  underlying  system,  or  dynamically configured via SNMP SET
       requests (and retained from one run of the agent to  the	 next).	  How‐
       ever,  certain  MIB  objects  can  be  configured or controlled via the
       snmpd.conf(5) file.

   System Group
       Most of the scalar objects in the 'system' group can be	configured  in
       this way:

       sysLocation STRING

       sysContact STRING

       sysName STRING
	      set the system location, system contact or system name (sysLoca‐
	      tion.0, sysContact.0 and sysName.0) for the agent	 respectively.
	      Ordinarily  these	 objects are writeable via suitably authorized
	      SNMP SET requests.  However, specifying one of these  directives
	      makes the corresponding object read-only, and attempts to SET it
	      will result in a notWritable error response.

       sysServices NUMBER
	      sets the value of the sysServices.0 object.  For a host  system,
	      a	 good  value is 72 (application + end-to-end layers).  If this
	      directive is not specified, then no value will be	 reported  for
	      the sysServices.0 object.

       sysDescr STRING

       sysObjectID OID
	      sets  the	 system	 description  or  object  ID  for  the	agent.
	      Although these MIB objects are not SNMP-writable,	 these	direc‐
	      tives  can be used by a network administrator to configure suit‐
	      able values for them.

   Interfaces Group
       interface NAME TYPE SPEED
	      can be used to provide appropriate type and speed	 settings  for
	      interfaces  where	 the agent fails to determine this information
	      correctly.  TYPE is a type value as given in the IANAifType-MIB,
	      and  can	be specified numerically or by name (assuming this MIB
	      is loaded).

   Host Resources Group
       This requires that the agent was built with support for the host module
       (which  is  now	included as part of the default build configuration on
       the major supported platforms).

       ignoreDisk STRING
	      controls which disk devices are scanned as  part	of  populating
	      the  hrDiskStorageTable (and hrDeviceTable).  The HostRes imple‐
	      mentation code includes a list of disk device patterns appropri‐
	      ate  for	the  current operating system, some of which may cause
	      the agent to block when trying to open  the  corresponding  disk
	      devices.	 This  might  lead  to	a  timeout  when walking these
	      tables, possibly	resulting  in  inconsistent  behaviour.	  This
	      directive	 can  be  used	to  specify particular devices (either
	      individually or wildcarded) that should not be checked.

	      Note:  Please consult the source (host/hr_disk.c) and check  for
		     the Add_HR_Disk_entry calls relevant for a particular O/S
		     to determine the list of devices that will be scanned.

	      The pattern can include one or more wildcard  expressions.   See
	      snmpd.examples(5) for illustration of the wildcard syntax.

       skipNFSInHostResources true
	      controls whether NFS and NFS-like file systems should be omitted
	      from the hrStorageTable (true or 1) or not (false or 0, which is
	      the  default).   If  the Net-SNMP agent gets hung on NFS-mounted
	      filesystems, you can try setting this to '1'.

       storageUseNFS [1|2]
	      controls how NFS and NFS-like file systems should be reported in
	      the hrStorageTable.  as 'Network Disks' (1) or 'Fixed Disks' (2)
	      Historically, the Net-SNMP agent has reported such file  systems
	      as 'Fixed Disks', and this is still the default behaviour.  Set‐
	      ting this directive to '1' reports such file systems as

   Process Monitoring
       The hrSWRun group of the Host Resources MIB provides information	 about
       individual  processes  running on the local system.  The prTable of the
       UCD-SNMP-MIB complements this by reporting on selected services	(which
       may  involve  multiple  processes).   This  requires that the agent was
       built with support for the ucd-snmp/proc module (which is  included  as
       part of the default build configuration).

       proc NAME [MAX [MIN]]
	      monitors	the  number of processes called NAME (as reported by "
	      -acx") running on the local system.

	      If the number of NAMEd processes is less	than  MIN  or  greater
	      than  MAX,  then	the corresponding prErrorFlag instance will be
	      set to 1, and a suitable description message  reported  via  the
	      prErrMessage instance.

	      Note:  This  situation  will not automatically trigger a trap to
		     report the problem - see the  DisMan  Event  MIB  section
		     later.

	      If  neither MAX nor MIN are specified (or are both 0), they will
	      default to infinity and 1 respectively  ("at  least  one").   If
	      only  MAX	 is  specified,	 MIN  will default to 0 ("no more than
	      MAX").

       procfix NAME PROG ARGS
	      registers a command that can be run to fix errors with the given
	      process  NAME.  This will be invoked when the corresponding prE‐
	      rrFix instance is set to 1.

	      Note:  This command will not be invoked automatically.

	      The procfix directive must be specified after the matching  proc
	      directive, and cannot be used on its own.

       If  no  proc directives are defined, then walking the prTable will fail
       (noSuchObject).

   Disk Usage Monitoring
       This requires that the agent  was  built	 with  support	for  the  ucd-
       snmp/disk  module  (which is included as part of the default build con‐
       figuration).

       disk PATH [ MINSPACE | MINPERCENT% ]
	      monitors the disk mounted at PATH for available disk space.

	      The minimum threshold can either be specified in	Kb  (MINSPACE)
	      or  as  a	 percentage  of the total disk (MINPERCENT% with a '%'
	      character), defaulting to 100Kb if neither  are  specified.   If
	      the  free disk space falls below this threshold, then the corre‐
	      sponding dskErrorFlag instance will be set to 1, and a  suitable
	      description message reported via the dskErrorMsg instance.

	      Note:  This  situation  will not automatically trigger a trap to
		     report the problem - see the  DisMan  Event  MIB  section
		     later.

       includeAllDisks MINPERCENT%
	      configures  monitoring  of  all disks found on the system, using
	      the specified (percentage) threshold.  The threshold  for	 indi‐
	      vidual  disks  can  be  adjusted	using suitable disk directives
	      (which can come  either  before  or  after  the  includeAllDisks
	      directive).

	      Note:  Whether   disk   directives   appears   before  or	 after
		     includeAllDisks may affect the indexing of the dskTable.

	      Only one includeAllDisks directive should	 be  specified	-  any
	      subsequent copies will be ignored.

	      The  list	 of  mounted  disks  will be determined when the agent
	      starts using the setmntent(3) and getmntent(3), or fopen(3)  and
	      getmntent(3),  or setfsent(3)  and  getfsent(3) system calls. If
	      none of the above system calls are available then the root  par‐
	      tition   "/" (which  is  assumed to exist on any UNIX based sys‐
	      tem) will be monitored.	Disks  mounted	after  the  agent  has
	      started will not be monitored.

       If  neither  any	 disk  directives or includeAllDisks are defined, then
       walking the dskTable will fail (noSuchObject).

   System Load Monitoring
       This requires that the agent was built with support for either the ucd-
       snmp/loadave module or the ucd-snmp/memory module respectively (both of
       which are included as part of the default build configuration).

       load MAX1 [MAX5 [MAX15]]
	      monitors the  load  average  of  the  local  system,  specifying
	      thresholds  for  the  1-minute, 5-minute and 15-minute averages.
	      If any of these loads exceed the associated maximum value,  then
	      the  corresponding  laErrorFlag instance will be set to 1, and a
	      suitable	description  message  reported	via  the  laErrMessage
	      instance.

	      Note:  This  situation  will not automatically trigger a trap to
		     report the problem - see the  DisMan  Event  MIB  section
		     later.

	      If  the  MAX15 threshold is omitted, it will default to the MAX5
	      value.  If both MAX5 and MAX15 are omitted, they will default to
	      the  MAX1	 value.	 If this directive is not specified, all three
	      thresholds will default to a value of DEFMAXLOADAVE.

	      If a threshold value of 0 is given, the agent  will  not	report
	      errors  via  the relevant laErrorFlag or laErrMessage instances,
	      regardless of the current load.

       Unlike the proc and disk directives, walking the	 walking  the  laTable
       will  succeed (assuming the ucd-snmp/loadave module was configured into
       the agent), even if the load directive is not present.

       swap MIN
	      monitors the amount of swap space available on the local system.
	      If  this	falls below the specified threshold (MIN Kb), then the
	      memErrorSwap object will be set to 1, and a suitable description
	      message reported via memSwapErrorMsg.

	      Note:  This  situation  will not automatically trigger a trap to
		     report the problem - see the  DisMan  Event  MIB  section
		     later.
       If this directive is not specified, the default threshold is 16 Mb.

   Log File Monitoring
       This requires that the agent was built with support for either the ucd-
       snmp/file or ucd-snmp/logmatch modules respectively (both of which  are
       included as part of the default build configuration).

       file FILE [MAXSIZE]
	      monitors	the size of the specified file (in Kb).	 If MAXSIZE is
	      specified, and the size of the file exceeds this threshold, then
	      the corresponding fileErrorFlag instance will be set to 1, and a
	      suitable	description  message  reported	via  the  fileErrorMsg
	      instance.

	      Note:  This  situation  will not automatically trigger a trap to
		     report the problem - see the  DisMan  Event  MIB  section
		     later.

	      A maximum of 20 files can be monitored.

       If no file directives are defined, then walking the fileTable will fail
       (noSuchObject).

       logmatch NAME PATH CYCLETIME REGEX
	      monitors the specified file for occurances of the specified pat‐
	      tern REGEX.

	      A maximum of 50 files can be monitored.

       If  no  logmatch directives are defined, then walking the logMatchTable
       will fail (noSuchObject).

ACTIVE MONITORING
       The usual behaviour of an SNMP agent  is	 to  wait  for	incoming  SNMP
       requests	 and  respond  to them - if no requests are received, an agent
       will typically not initiate any actions. This section describes various
       directives that can configure snmpd to take a more active role.

   Notification Handling
       trapcommunity STRING
	      defines  the  default  community	string to be used when sending
	      traps.  Note that this directive must be used prior to any  com‐
	      munity-based trap destination directives that need to use it.

       trapsink HOST [COMMUNITY [PORT]]

       trap2sink HOST [COMMUNITY [PORT]]

       informsink HOST [COMMUNITY [PORT]]
	      define  the  address  of	a notification receiver that should be
	      sent SNMPv1 TRAPs, SNMPv2c TRAP2s, or  SNMPv2  INFORM  notifica‐
	      tions  respectively.  See the section LISTENING ADDRESSES in the
	      snmpd(8) manual page for more information about  the  format  of
	      listening	 addresses.   If  COMMUNITY is not specified, the most
	      recent trapcommunity string will be used.

	      If the transport address does not include an explicit port spec‐
	      ification,  then	PORT  will be used.  If this is not specified,
	      the well known SNMP trap port (162) will be used.

	      Note:  This mechanism is being  deprecated,  and	the  listening
		     port  should be specified via the transport specification
		     HOST instead.

	      If several sink directives are  specified,  multiple  copies  of
	      each  notification  (in  the appropriate formats) will be gener‐
	      ated.

	      Note:  It is not normally appropriate to list two (or all three)
		     sink directives with the same destination.

       trapsess [SNMPCMD_ARGS] HOST
	      provides a more generic mechanism for defining notification des‐
	      tinations.  SNMPCMD_ARGS	should	be  the	 command-line  options
	      required	for  an equivalent snmptrap (or snmpinform) command to
	      send the desired notification.  The option -Ci can be used (with
	      -v2c  or	-v3) to generate an INFORM notification rather than an
	      unacknowledged TRAP.

	      This is the  appropriate	directive  for	defining  SNMPv3  trap
	      receivers.  See http://www.net-snmp.org/tutorial/tutorial-5/com‐
	      mands/snmptrap-v3.html for more information about SNMPv3 notifi‐
	      cation behaviour.

       authtrapenable {1|2}
	      determines  whether  to  generate	 authentication	 failure traps
	      (enabled(1)) or not (disabled(2) - the default).	Ordinarily the
	      corresponding  MIB  object  (snmpEnableAuthenTraps.0)  is	 read-
	      write, but specifying this directive  makes  this	 object	 read-
	      only, and attempts to set the value via SET requests will result
	      in a notWritable error response.

       v1trapaddress HOST
	      defines the agent address, which is inserted into SNMPv1	TRAPs.
	      Arbitrary	 local	IPv4  address  is  chosen  if  this  option is
	      ommited. This option is useful mainly when the agent is  visible
	      from  outside  world  by specific address only (e.g.  because of
	      network address translation or firewall).

   DisMan Event MIB
       The previous directives can be used to configure where traps should  be
       sent, but are not concerned with when to send such traps (or what traps
       should be generated).  This is the domain of the Event MIB -  developed
       by the Distributed Management (DisMan) working group of the IETF.

       This  requires  that  the  agent	 was  built  with support for the dis‐
       man/event module (which is now included as part of  the	default	 build
       configuration for the most recent distribution).

	      Note:  The  behaviour  of	 the  latest implementation differs in
		     some minor respects from the previous code - nothing  too
		     significant,  but existing scripts may possibly need some
		     minor adjustments.

       iquerySecName NAME

       agentSecName NAME
	      specifies the default SNMPv3 username, to be  used  when	making
	      internal	queries	 to retrieve any necessary information (either
	      for evaluating the monitored expression, or building a notifica‐
	      tion  payload).	These internal queries always use SNMPv3, even
	      if normal querying of the agent is done using SNMPv1 or SNMPv2c.

	      Note that this user must also be explicitly created (createUser)
	      and  given appropriate access rights (e.g. rouser).  This direc‐
	      tive is purely concerned with defining which user should be used
	      - not with actually setting this user up.

       monitor [OPTIONS] NAME EXPRESSION
	      defines  a  MIB  object to monitor.  If the EXPRESSION condition
	      holds (see below), then  this  will  trigger  the	 corresponding
	      event,  and either send a notification or apply a SET assignment
	      (or both).  Note that the event will  only  be  triggered	 once,
	      when  the expression first matches.  This monitor entry will not
	      fire again until the monitored condition	first  becomes	false,
	      and then matches again.  NAME is an administrative name for this
	      expression, and is used for indexing  the	 mteTriggerTable  (and
	      related  tables).	  Note also that such monitors use an internal
	      SNMPv3 request to retrieve the values being monitored  (even  if
	      normal  agent queries typically use SNMPv1 or SNMPv2c).  See the
	      iquerySecName token described above.

       EXPRESSION
	      There are three types of monitor	expression  supported  by  the
	      Event MIB - existence, boolean and threshold tests.

	      OID | ! OID | != OID
		     defines  an existence(0) monitor test.  A bare OID speci‐
		     fies a present(0) test, which will fire when (an instance
		     of)  the  monitored OID is created.  An expression of the
		     form ! OID specifies an absent(1) test, which  will  fire
		     when the monitored OID is delected.  An expression of the
		     form != OID specifies a changed(2) test, which will  fire
		     whenever  the monitored value(s) change.  Note that there
		     must be whitespace before the OID token.

	      OID OP VALUE
		     defines a boolean(1) monitor test.	 OP should be  one  of
		     the  defined  comparison operators (!=, ==, <, <=, >, >=)
		     and VALUE should be an integer value to compare  against.
		     Note  that	 there must be whitespace around the OP token.
		     A comparison such as OID !=0 will	not  be	 handled  cor‐
		     rectly.

	      OID MIN MAX [DMIN DMAX]
		     defines  a	 threshold(2)  monitor	test.  MIN and MAX are
		     integer values, specifying lower  and  upper  thresholds.
		     If	 the  value of the monitored OID falls below the lower
		     threshold (MIN) or rises above the upper threshold (MAX),
		     then  the	monitor	 entry	will trigger the corresponding
		     event.

		     Note that the rising threshold event  will	 only  be  re-
		     armed  when  the  monitored  value	 falls below the lower
		     threshold (MIN).  Similarly, the falling threshold	 event
		     will be re-armed by the upper threshold (MAX).

		     The optional parameters DMIN and DMAX configure a pair of
		     similar threshold tests, but working with the delta  dif‐
		     ferences between successive sample values.

       OPTIONS
	      There  are various options to control the behaviour of the moni‐
	      tored expression.	 These include:

	      -D     indicates that the expression should be  evaluated	 using
		     delta  differences between sample values (rather than the
		     values themselves).

	      -d OID

	      -di OID
		     specifies a discontinuity	marker	for  validating	 delta
		     differences.   A -di object instance will be used exactly
		     as given.	A -d object will have the instance  subidenti‐
		     fiers  from  the  corresponding  (wildcarded)  expression
		     object appended.  If the -I flag is specified, then there
		     is no difference between these two options.

		     This option also implies -D.

	      -e EVENT
		     specifies the event to be invoked when this monitor entry
		     is triggered.  If this option is not given,  the  monitor
		     entry  will  generate  one	 of the standard notifications
		     defined in the DISMAN-EVENT-MIB.

	      -I     indicates that the monitored expression should be applied
		     to	 the  specified OID as a single instance.  By default,
		     the OID will be treated as a wildcarded object,  and  the
		     monitor expanded to cover all matching instances.

	      -i OID

	      -o OID define  additional	 varbinds to be added to the notifica‐
		     tion payload when this  monitor  trigger  fires.	For  a
		     wildcarded expression, the suffix of the matched instance
		     will be added to any OIDs specified using -o, while  OIDs
		     specified	using  -i  will be treated as exact instances.
		     If the -I flag is specified, then there is no  difference
		     between these two options.

		     See strictDisman for details of the ordering of notifica‐
		     tion payloads.

	      -r FREQUENCY
		     monitors the given expression  every  FREQUENCY  seconds.
		     By	 default,  the expression will be evaluated every 600s
		     (10 minutes).

	      -S     indicates that the monitor expression should not be eval‐
		     uated  when the agent first starts up.  The first evalua‐
		     tion will be done once  the  first	 repeat	 interval  has
		     expired.

	      -s     indicates that the monitor expression should be evaluated
		     when the agent first starts up.  This is the default  be‐
		     haviour.

		     Note:  Notifications triggered by this initial evaluation
			    will be sent before the coldStart trap.

	      -u SECNAME
		     specifies a security name to use for scanning  the	 local
		     host,  instead of the default iquerySecName.  Once again,
		     this user must be explicitly created and  given  suitable
		     access rights.

       notificationEvent ENAME NOTIFICATION [-n] [-i OID | -o OID ]*
	      defines a notification event named ENAME.	 This can be triggered
	      from a given monitor entry by specifying	the  option  -e	 ENAME
	      (see  above).   NOTIFICATION  should be the OID of the NOTIFICA‐
	      TION-TYPE definition for the notification to be generated.

	      If the -n option is given, the notification payload will include
	      the  standard varbinds as specified in the OBJECTS clause of the
	      notification MIB definition.  This option must  come  after  the
	      NOTIFICATION  OID	 (and  the relevant MIB file must be available
	      and loaded by the agent).	 Otherwise,  these  varbinds  must  be
	      listed  explicitly  (either here or in the corresponding monitor
	      directive).

	      The -i OID and -o OID options specify additional varbinds to  be
	      appended	to  the notification payload, after the standard list.
	      If the monitor entry that triggered this event involved a	 wild‐
	      carded  expression,  the	suffix of the matched instance will be
	      added to any OIDs specified using -o, while OIDs specified using
	      -i will be treated as exact instances.  If the -I flag was spec‐
	      ified to the monitor directive,  then  there  is	no  difference
	      between these two options.

       setEvent ENAME [-I] OID = VALUE
	      defines  a  set event named ENAME, assigning the (integer) VALUE
	      to the specified OID.  This can be triggered from a given	 moni‐
	      tor entry by specifying the option -e ENAME (see above).

	      If  the monitor entry that triggered this event involved a wild‐
	      carded expression, the suffix of the matched instance will  nor‐
	      mally  be	 added	to  the	 OID.  If the -I flag was specified to
	      either of the monitor or setEvent directives, the specified  OID
	      will be regarded as an exact single instance.

       strictDisman yes
	      The  definition  of  SNMP notifications states that the varbinds
	      defined in the OBJECT clause should come	first  (in  the	 order
	      specified),  followed by any "extra" varbinds that the notifica‐
	      tion generator feels might be useful.  The most natural approach
	      would  be to associate these mandatory varbinds with the notifi‐
	      cationEvent entry, and append any varbinds associated  with  the
	      monitor entry that triggered the notification to the end of this
	      list.  This is the default behaviour of the Net-SNMP  Event  MIB
	      implementation.

	      Unfortunately,  the  DisMan  Event  MIB  specifications actually
	      state that the trigger-related varbinds should come first,  fol‐
	      lowed  by the event-related ones.	 This directive can be used to
	      restore this strictly-correct (but inappropriate) behaviour.

	      Note:  Strict DisMan ordering may result in  generating  invalid
		     notifications  payload  lists if the notificationEvent -n
		     flag is used together with monitor	 -o  (or  -i)  varbind
		     options.

	      If no monitor entries specify payload varbinds, then the setting
	      of this directive is irrelevant.

       linkUpDownNotifications yes
	      will configure the Event MIB tables to monitor the  ifTable  for
	      network  interfaces  being  taken	 up  or down, and triggering a
	      linkUp or linkDown notification as appropriate.

	      This is exactly equivalent to the configuration:

		     notificationEvent	linkUpTrap    linkUp   ifIndex ifAdminStatus ifOperStatus
		     notificationEvent	linkDownTrap  linkDown ifIndex ifAdminStatus ifOperStatus

		     monitor  -r 60 -e linkUpTrap   "Generate linkUp" ifOperStatus != 2
		     monitor  -r 60 -e linkDownTrap "Generate linkDown" ifOperStatus == 2

       defaultMonitors yes
	      will configure the Event MIB tables to monitor the various  UCD-
	      SNMP-MIB	tables	for  problems (as indicated by the appropriate
	      xxErrFlag column objects).

	      This is exactly equivalent to the configuration:

		     monitor   -o prNames -o prErrMessage "process table" prErrorFlag != 0
		     monitor   -o memErrorName -o memSwapErrorMsg "memory" memSwapError != 0
		     monitor   -o extNames -o extOutput "extTable" extResult != 0
		     monitor   -o dskPath -o dskErrorMsg "dskTable" dskErrorFlag != 0
		     monitor   -o laNames -o laErrMessage  "laTable" laErrorFlag != 0
		     monitor   -o fileName -o fileErrorMsg  "fileTable" fileErrorFlag != 0

       In both these latter cases, the snmpd.conf must also contain a  iquery‐
       SecName	directive,  together with a corresponding createUser entry and
       suitable access control configuration.

   DisMan Schedule MIB
       The DisMan working group also produced a mechanism for scheduling  par‐
       ticular	actions	 (a  specified	SET  assignment) at given times.  This
       requires that the agent was built with support for the  disman/schedule
       module  (which  is  included as part of the default build configuration
       for the most recent distribution).

       There are three ways of specifying the scheduled action:

       repeat FREQUENCY OID = VALUE
	      configures a SET assignment of the (integer) VALUE  to  the  MIB
	      instance OID, to be run every FREQUENCY seconds.

       cron MINUTE HOUR DAY MONTH WEEKDAY  OID = VALUE
	      configures  a  SET  assignment of the (integer) VALUE to the MIB
	      instance OID, to be run at the times  specified  by  the	fields
	      MINUTE to WEEKDAY.  These follow the same pattern as the equiva‐
	      lent crontab(5) fields.

	      Note:  These fields should be specified as  a  (comma-separated)
		     list  of  numeric values.	Named values for the MONTH and
		     WEEKDAY fields are not supported, and neither  are	 value
		     ranges. A wildcard match can be specified as '*'.

	      The  DAY field can also accept negative values, to indicate days
	      counting backwards from the end of the month.

       at MINUTE HOUR DAY MONTH WEEKDAY	 OID = VALUE
	      configures a one-shot SET assignment, to be  run	at  the	 first
	      matching time as specified by the fields MINUTE to WEEKDAY.  The
	      interpretation of these fields is exactly the same  as  for  the
	      cron directive.

EXTENDING AGENT FUNCTIONALITY
       One  of the first distinguishing features of the original UCD suite was
       the ability to extend the functionality of the  agent  -	 not  just  by
       recompiling  with code for new MIB modules, but also by configuring the
       running agent to report additional information. There are a  number  of
       techniques to support this, including:

       ·      running external commands (exec, extend, pass)

       ·      loading new code dynamically (embedded perl, dlmod)

       ·      communicating with other agents (proxy, SMUX, AgentX)

   Arbitrary Extension Commands
       The  earliest extension mechanism was the ability to run arbitrary com‐
       mands or shell scripts. Such commands do not need to be aware  of  SNMP
       operations, or conform to any particular behaviour - the MIB structures
       are designed to accommodate any form of command output.	 Use  of  this
       mechanism  requires  that the agent was built with support for the ucd-
       snmp/extensible and/or agent/extend modules (which are both included as
       part of the default build configuration).

       exec [MIBOID] NAME PROG ARGS

       sh [MIBOID] NAME PROG ARGS
	      invoke  the  named  PROG with arguments of ARGS.	By default the
	      exit status and first line of output from the  command  will  be
	      reported via the extTable, discarding any additional output.

	      Note:  Entries  in  this table appear in the order they are read
		     from the configuration file.  This means that adding  new
		     exec  (or	sh)  directives	 and restarting the agent, may
		     affect the indexing of other entries.

	      The PROG argument for exec directives must be a full path	 to  a
	      real  binary,  as it is executed via the exec() system call.  To
	      invoke a shell script, use the sh directive instead.

	      If MIBOID is specified, then the results will be rooted at  this
	      point   in  the  OID  tree,  returning  the  exit	 statement  as
	      MIBOID.100.0 and the entire command  output  in  a  pseudo-table
	      based at MIBNUM.101 - with one 'row' for each line of output.

	      Note:  The  layout  of  this  "relocatable" form of exec (or sh)
		     output does not strictly  form  a	valid  MIB  structure.
		     This  mechanism  is  being	 deprecated  -	please see the
		     extend directive (described below) instead.

	      The agent does not cache the exit status or output of  the  exe‐
	      cuted program.

       execfix NAME PROG ARGS
	      registers a command that can be invoked on demand - typically to
	      respond to or fix errors	with  the  corresponding  exec	or  sh
	      entry.   When  the extErrFix instance for a given NAMEd entry is
	      set to the integer value of 1, this command will be called.

	      Note:  This directive can only be used  in  combination  with  a
		     corresponding exec or sh directive, which must be defined
		     first.  Attempting to  define  an	unaccompanied  execfix
		     directive will fail.

       exec  and sh extensions can only be configured via the snmpd.conf file.
       They cannot be set up via SNMP SET requests.

       extend [MIBOID] NAME PROG ARGS
	      works in a similar manner to the exec directive, but with a num‐
	      ber  of  improvements.  The MIB tables (nsExtendConfigTable etc)
	      are indexed by the NAME token, so are unaffected by the order in
	      which  entries are read from the configuration files.  There are
	      two result tables - one  (nsExtendOutput1Table)  containing  the
	      exit status, the first line and full output (as a single string)
	      for each extend entry, and the other (nsExtendOutput2Table) con‐
	      taining the complete output as a series of separate lines.

	      If MIBOID is specified, then the configuration and result tables
	      will be rooted at this point in the OID tree, but are  otherwise
	      structured in exactly the same way. This means that several sep‐
	      arate extend directives can specify the same MIBOID root,	 with‐
	      out conflicting.

	      The  exit	 status	 and output is cached for each entry individu‐
	      ally, and can be cleared (and the caching behaviour  configured)
	      using the nsCacheTable.

       extendfix NAME PROG ARGS
	      registers	 a  command  that can be invoked on demand, by setting
	      the appropriate nsExtendRunType instance to the  value  run-com‐
	      mand(3).	Unlike the equivalent execfix, this directive does not
	      need to be paired with a corresponding  extend  entry,  and  can
	      appear on its own.

       Both  extend  and  extendfix  directives can be configured dynamically,
       using SNMP SET requests to the NET-SNMP-EXTEND-MIB.

   MIB-Specific Extension Commands
       The first group of extension directives invoke arbitrary commands,  and
       rely  on	 the  MIB  structure  (and management applications) having the
       flexibility to accommodate and interpret the output.  This is a	conve‐
       nient  way  to make information available quickly and simply, but is of
       no use when implementing specific MIB objects, where the extension must
       conform	to  the	 structure  of	the MIB (rather than vice versa).  The
       remaining extension mechanisms are all concerned with such MIB-specific
       situations  - starting with "pass-through" scripts.  Use of this mecha‐
       nism requires that the agent  was  built	 with  support	for  the  ucd-
       snmp/pass and ucd-snmp/pass_persist modules (which are both included as
       part of the default build configuration).

       pass [-p priority] MIBOID PROG
	      will pass control of the subtree rooted at MIBOID to the	speci‐
	      fied  PROG  command.   GET  and GETNEXT requests for OIDs within
	      this tree will trigger this command, called as:

		     PROG -g OID

		     PROG -n OID

	      respectively, where OID is the requested OID.  The PROG  command
	      should  return  the  response  varbind  as  three separate lines
	      printed to stdout - the first line should	 be  the  OID  of  the
	      returned	value,	the second should be its TYPE (one of the text
	      strings integer, gauge, counter, timeticks, ipaddress, objectid,
	      or string ), and the third should be the value itself.

	      If  the  command	cannot return an appropriate varbind - e.g the
	      specified OID did not correspond to a valid instance for	a  GET
	      request,	or  there  were no following instances for a GETNEXT -
	      then it should exit without producing  any  output.   This  will
	      result  in  an SNMP noSuchName error, or a noSuchInstance excep‐
	      tion.

		     Note:  The SMIv2 type counter64 and  SNMPv2  noSuchObject
			    exception are not supported.

	      A SET request will result in the command being called as:

		     PROG -s OID TYPE VALUE

	      where  TYPE  is  one  of the tokens listed above, indicating the
	      type of the value passed as the third parameter.

	      If the assignment is successful, the PROG	 command  should  exit
	      without  producing  any  output.	Errors	should be indicated by
	      writing one of the strings not-writable, or wrong-type  to  std‐
	      out, and the agent will generate the appropriate error response.

		     Note:  The other SNMPv2 errors are not supported.

	      In  either  case,	 the  command should exit once it has finished
	      processing.  Each request (and  each  varbind  within  a	single
	      request) will trigger a separate invocation of the command.

	      The  default  registration priority is 127.  This can be changed
	      by supplying the optional -p flag, with lower priority registra‐
	      tions being used in preference to higher priority values.

       pass_persist [-p priority] MIBOID PROG
	      will  also  pass	control of the subtree rooted at MIBOID to the
	      specified PROG command.  However this command will  continue  to
	      run  after  the initial request has been answered, so subsequent
	      requests can be processed without the startup overheads.

	      Upon initialization, PROG will be passed the string "PING\n"  on
	      stdin, and should respond by printing "PONG\n" to stdout.

	      For  GET	and GETNEXT requests, PROG will be passed two lines on
	      stdin, the command (get or getnext) and the requested  OID.   It
	      should  respond  by printing three lines to stdout - the OID for
	      the result varbind, the TYPE and the VALUE itself -  exactly  as
	      for  the	pass directive above.  If the command cannot return an
	      appropriate varbind, it should print print  "NONE\n"  to	stdout
	      (but continue running).

	      For  SET requests, PROG will be passed three lines on stdin, the
	      command (set) and the requested OID, followed by	the  type  and
	      value (both on the same line).  If the assignment is successful,
	      the command should print "DONE\n" to stdout.  Errors  should  be
	      indicated	 by  writing  one  of the strings not-writable, wrong-
	      type, wrong-length, wrong-value or inconsistent-value to stdout,
	      and  the agent will generate the appropriate error response.  In
	      either case, the command should continue running.

	      The registration priority can be changed using the  optional  -p
	      flag, just as for the pass directive.

       pass  and  pass_persist	extensions  can	 only  be  configured  via the
       snmpd.conf file.	 They cannot be set up via SNMP SET requests.

   Embedded Perl Support
       Programs using the previous extension mechanisms can be written in  any
       convenient  programming	language  -  including perl, which is a common
       choice for pass-through extensions in particular.  However the Net-SNMP
       agent  also  includes  support for embedded perl technology (similar to
       mod_perl for the Apache web server).  This allows the agent  to	inter‐
       pret perl scripts directly, thus avoiding the overhead of spawning pro‐
       cesses and initializing the perl system when a request is received.

       Use of this mechanism requires that the agent was  built	 with  support
       for the embedded perl mechanism, which is not part of the default build
       environment.  It	 must  be  explicitly  included	 by   specifying   the
       '--enable-embedded-perl'	 option to the configure script when the pack‐
       age is first built.

       If enabled, the following directives will be recognised:

       disablePerl true
	      will turn off embedded perl support entirely (e.g. if there  are
	      problems with the perl installation).

       perlInitFile FILE
	      loads the specified initialisation file (if present) immediately
	      before the first perl directive is parsed.   If  not  explicitly
	      specified,  the  agent  will look for the default initialisation
	      file /usr/share/snmp/snmp_perl.pl.

	      The default initialisation file creates an instance  of  a  Net‐
	      SNMP::agent object - a variable $agent which can be used to reg‐
	      ister perl-based MIB handler routines.

       perl EXPRESSION
	      evaluates the given expression.  This would typically register a
	      handler  routine to be called when a section of the OID tree was
	      requested:
		     perl use Data::Dumper;
		     perl sub myroutine	 { print "got called: ",Dumper(@_),"\n"; }
		     perl $agent->register('mylink', '.1.3.6.1.8765', \&myroutine);

	      This expression could also source an external file:
		     perl 'do /path/to/file.pl';

	      or  perform  any	other  perl-based  processing  that  might  be
	      required.

   Dynamically Loadable Modules
       Most  of	 the MIBs supported by the Net-SNMP agent are implemented as C
       code modules, which were compiled and linked into the  agent  libraries
       when  the  suite was first built.  Such implementation modules can also
       be compiled independently and loaded into the running agent once it has
       started.	  Use of this mechanism requires that the agent was built with
       support for the ucd-snmp/dlmod module (which is included as part of the
       default build configuration).

       dlmod NAME PATH
	      will  load the shared object module from the file PATH (an abso‐
	      lute filename), and call the initialisation routine init_NAME.

	      Note:  If the specified PATH is not a fully qualified  filename,
		     it will be interpreted relative to /usr/lib64/snmp/dlmod,
		     and .so will be appended to the filename.

       This functionality can also be configured using SNMP  SET  requests  to
       the UCD-DLMOD-MIB.

   Proxy Support
       Another	mechanism  for	extending the functionality of the agent is to
       pass selected requests (or selected varbinds) to	 another  SNMP	agent,
       which  can  be running on the same host (presumably listening on a dif‐
       ferent port), or on a remote system.  This can be viewed either as  the
       main  agent delegating requests to the remote one, or acting as a proxy
       for it.	Use of this mechanism requires that the agent was  built  with
       support for the ucd-snmp/proxy module (which is included as part of the
       default build configuration).

       proxy [-Cn CONTEXTNAME] [SNMPCMD_ARGS] HOST OID [REMOTEOID]
	      will pass any incoming requests under OID to the agent listening
	      on  the  port  specified by the transport address HOST.  See the
	      section LISTENING ADDRESSES in the snmpd(8) manual page for more
	      information about the format of listening addresses.

	      Note:  To	 proxy	the entire MIB tree, use the OID .1.3 (not the
		     top-level .1)

       The SNMPCMD_ARGS should provide sufficient version  and	administrative
       information to generate a valid SNMP request (see snmpcmd(1)).

       Note:  The  proxied  request  will  not use the administrative settings
	      from the original request.

       If a CONTEXTNAME is specified, this will register the proxy  delegation
       within  the  named context in the local agent.  Defining multiple proxy
       directives for the same OID but different contexts can be used to query
       several	remote agents through a single proxy, by specifying the appro‐
       priate SNMPv3 context in the incoming request (or using	suitable  con‐
       figured community strings - see the com2sec directive).

       Specifying  the	REMOID parameter will map the local MIB tree rooted at
       OID to an equivalent subtree rooted at REMOID on the remote agent.

   SMUX Sub-Agents
       The Net-SNMP agent supports the SMUX protocol (RFC 1227) to communicate
       with  SMUX-based	 subagents  (such  as gated, zebra or quagga).	Use of
       this mechanism requires that the agent was built with support  for  the
       smux  module,  which  is not part of the default build environment, and
       must be explicitly included by specifying the '--with-mib-modules=smux'
       option to the configure script when the package is first built.

	      Note:  This extension protocol has been officially deprecated in
		     favour of AgentX (see below).

       smuxpeer OID PASS
	      will register a subtree for SMUX-based processing, to be authen‐
	      ticated using the password PASS.	If a subagent (or "peer") con‐
	      nects to the agent and registers this subtree then requests  for
	      OIDs within it will be passed to that SMUX subagent for process‐
	      ing.

	      A suitable entry for an OSPF  routing  daemon  (such  as	gated,
	      zebra or quagga) might be something like
		     smuxpeer .1.3.6.1.2.1.14 ospf_pass

       smuxsocket <IPv4-address>
	      defines  the IPv4 address for SMUX peers to communicate with the
	      Net-SNMP agent.  The default is to listen on all IPv4 interfaces
	      ("0.0.0.0"),   unless  the  package  has	been  configured  with
	      "--enable-local-smux" at build time, which  causes  it  to  only
	      listen  on  127.0.0.1  by	 default. SMUX uses the well-known TCP
	      port 199.

       Note the Net-SNMP agent will only operate as a SMUX  master  agent.  It
       does not support acting in a SMUX subagent role.

   AgentX Sub-Agents
       The Net-SNMP agent supports the AgentX protocol (RFC 2741) in both mas‐
       ter and subagent roles.	Use of this mechanism requires that the	 agent
       was built with support for the agentx module (which is included as part
       of the default build configuration), and	 also  that  this  support  is
       explicitly enabled (e.g. via the snmpd.conf file).

       There  are two directives specifically relevant to running as an AgentX
       master agent:

       master agentx
	      will enable the AgentX functionality  and	 cause	the  agent  to
	      start  listening	for  incoming  AgentX registrations.  This can
	      also be activated by specifying the '-x' command-line option (to
	      specify an alternative listening socket).

       agentXPerms SOCKPERMS [DIRPERMS [USER|UID [GROUP|GID]]]
	      Defines  the permissions and ownership of the AgentX Unix Domain
	      socket, and the parent directories of  this  socket.   SOCKPERMS
	      and  DIRPERMS  must  be octal digits (see chmod(1) ). By default
	      this socket will only be accessible to subagents which have  the
	      same userid as the agent.

       There  is  one  directive specifically relevant to running as an AgentX
       sub-agent:

       agentXPingInterval NUM
	      will make the subagent try and reconnect every  NUM  seconds  to
	      the master if it ever becomes (or starts) disconnected.

       The  remaining  directives  are relevant to both AgentX master and sub-
       agents:

       agentXSocket [<transport-specifier>:]<transport-address>[,...]
	      defines the address the master agent listens at, or the subagent
	      should  connect  to.   The  default  is  the  Unix Domain socket
	      "/var/run/agentx/master".	   Another   common   alternative   is
	      tcp:localhost:705.   See	the section LISTENING ADDRESSES in the
	      snmpd(8) manual page for more information about  the  format  of
	      addresses.

	      Note:  Specifying an AgentX socket does not automatically enable
		     AgentX  functionality  (unlike  the   '-x'	  command-line
		     option).

       agentXTimeout NUM
	      defines  the timeout period (NUM seconds) for an AgentX request.
	      Default is 1 second.

       agentXRetries NUM
	      defines the number of retries for an AgentX request.  Default is
	      5 retries.

       net-snmp	 ships	with  both  C and Perl APIs to develop your own AgentX
       subagent.

OTHER CONFIGURATION
       override [-rw] OID TYPE VALUE
	      This directive allows you to override a particular  OID  with  a
	      different	 value	(and possibly a different type of value).  The
	      -rw flag will allow snmp SETs to	modify	it's  value  as	 well.
	      (note  that  if  you're  overriding original functionality, that
	      functionality will be entirely lost.  Thus SETS will do  nothing
	      more than modify the internal overridden value and will not per‐
	      form any of the original functionality intended to  be  provided
	      by the MIB object.  It's an emulation only.)  An example:

		     override sysDescr.0 octet_str "my own sysDescr"

	      That  line will set the sysDescr.0 value to "my own sysDescr" as
	      well as make it modifiable with SNMP  SETs  as  well  (which  is
	      actually illegal according to the MIB specifications).

	      Note  that  care must be taken when using this.  For example, if
	      you try to override a property  of  the  3rd  interface  in  the
	      ifTable  with  a	new  value  and later the numbering within the
	      ifTable changes it's index ordering you'll end up with  problems
	      and  your	 modified value won't appear in the right place in the
	      table.

	      Valid  TYPEs  are:  integer,  uinteger,  octet_str,   object_id,
	      counter,	null (for gauges, use "uinteger"; for bit strings, use
	      "octet_str").  Note that setting an object to "null" effectively
	      delete's	it as being accessible.	 No VALUE needs to be given if
	      the object type is null.

	      More types should be available in the future.

       If you're trying to figure out aspects of the various mib modules (pos‐
       sibly some that you've added yourself), the following may help you spit
       out some useful debugging information.	First  off,  please  read  the
       snmpd  manual  page  on	the -D flag.  Then the following configuration
       snmpd.conf token, combined with the -D flag, can produce useful output:

       injectHandler HANDLER modulename
	      This will insert new handlers into the section of the  mib  tree
	      referenced by "modulename".  The types of handlers available for
	      insertion are:

	      stash_cache
		     Caches information returned from the lower	 level.	  This
		     greatly help the performance of the agent, at the cost of
		     caching the data such that its no longer  "live"  for  30
		     seconds  (in  this	 future,  this	will be configurable).
		     Note that this means snmpd will use more memory  as  well
		     while  the	 information  is  cached.  Currently this only
		     works for handlers registered  using  the	table_iterator
		     support,  which is only a few mib tables.	To use it, you
		     need to make sure to install it before the table_iterator
		     point in the chain, so to do this:

				       injectHandler   stash_cache   NAME  ta‐
		     ble_iterator

		     If you want a table to play with, try walking the	nsMod‐
		     uleTable with and without this injected.

	      debug  Prints   out  lots	 of  debugging	information  when  the
		     -Dhelper:debug flag is passed to the snmpd application.

	      read_only
		     Forces turning off write support for the given module.

	      serialize
		     If a module is failing to handle multiple requests	 prop‐
		     erly  (using the new 5.0 module API), this will force the
		     module to only receive one request at a time.

	      bulk_to_next
		     If a module registers to handle getbulk support, but  for
		     some  reason  is  failing	to implement it properly, this
		     module will  convert  all	getbulk	 requests  to  getnext
		     requests before the final module receives it.

       dontLogTCPWrappersConnects
	      If  the  snmpd  was  compiled  with TCP Wrapper support, it logs
	      every connection made to the agent. This	setting	 disables  the
	      log  messages  for accepted connections. Denied connections will
	      still be logged.

       Figuring out module names
	      To figure out which modules you can inject things into, run snm‐
	      pwalk  on	 the nsModuleTable which will give a list of all named
	      modules registered within the agent.

   Internal Data tables
       table NAME

       add_row NAME INDEX(ES) VALUE(S)

NOTES
       o      The Net-SNMP agent can be instructed to re-read the various con‐
	      figuration files, either via an snmpset assignment of integer(1)
	      to			   UCD-SNMP-MIB::versionUpdateConfig.0
	      (.1.3.6.1.4.1.2021.100.11.0),  or	 by sending a kill -HUP signal
	      to the agent process.

       o      All directives listed with a value of "yes"  actually  accept  a
	      range  of	 boolean  values.   These will accept any of 1, yes or
	      true to enable the corresponding behaviour, or any of 0,	no  or
	      false  to	 disable it.  The default in each case is for the fea‐
	      ture to be turned off, so these directives  are  typically  only
	      used to enable the appropriate behaviour.

EXAMPLE CONFIGURATION FILE
       See  the EXAMPLE.CONF file in the top level source directory for a more
       detailed example of how the above information is used in real examples.

FILES
       /etc/snmp/snmpd.conf

SEE ALSO
       snmpconf(1), snmpusm(1), snmp.conf(5), snmp_config(5), snmpd(8),	 EXAM‐
       PLE.conf, read_config(3).

4th Berkeley Distribution	  08 Feb 2002			 SNMPD.CONF(5)
[top]

List of man pages available for SuSE

Copyright (c) for man pages and the logo by the respective OS vendor.

For those who want to learn more, the polarhome community provides shell access and support.

[legal] [privacy] [GNU] [policy] [cookies] [netiquette] [sponsors] [FAQ]
Tweet
Polarhome, production since 1999.
Member of Polarhome portal.
Based on Fawad Halim's script.
....................................................................
Vote for polarhome
Free Shell Accounts :: the biggest list on the net