Provided by: snmpd_5.4.1~dfsg-7.1ubuntu6_i386 bug

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)
       manual 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
       providing 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
              variable  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
              considered 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
              authentication 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)
              command.

              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/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 password 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
              respectively.  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
       distinct 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 configuration 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
              hostname  (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.
              Otherwise 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
              models  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
              subidentifiers 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
              subidentifier:

                     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
              security  model  and  minimum  security level, and in a specific
              context) to one of three views, depending on the  request  being
              processed.

              LEVEL  is  one  of  noauth,  auth, or priv.  PREFX specifies how
              CONTEXT should be matched against the context  of  the  incoming
              request,  either  exact  or  prefix.   READ,  WRITE  and  NOTIFY
              specifies 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
              flexibility.  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
              authcommunity.

       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
              unauthenticated 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,
              typically listing the  view  types  as  read  or  read,write  as
              appropriate.     (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).
       However, 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
              (sysLocation.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
              directives  can  be used by a network administrator to configure
              suitable 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
              implementation code includes a  list  of  disk  device  patterns
              appropriate  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.
              Setting 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
              "/bin/ps -e") 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
              prErrFix 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
       configuration).

       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
              corresponding 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
              individual 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
              partition   "/"  (which   is  assumed to exist on any UNIX based
              system) 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
              pattern 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
              community-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
              notifications 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
              specification,  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
              generated.

              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
              destinations.   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/commands/snmptrap-v3.html  for more
              information about SNMPv3 notification 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.

   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
       disman/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
              notification  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
              directive 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
                     specifies 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
                     correctly.

              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
                     differences between successive sample values.

       OPTIONS
              There  are  various  options  to  control  the  behaviour of the
              monitored 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
                     subidentifiers   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
                     notification 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
                     notification 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
                     evaluated  when  the  agent  first  starts up.  The first
                     evaluation 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
                     behaviour.

                      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
              NOTIFICATION-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
              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 was
              specified 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
              monitor entry by specifying the option -e ENAME (see above).

              If  the  monitor  entry  that  triggered  this  event involved a
              wildcarded expression, the suffix of the matched  instance  will
              normally  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
              notification generator feels might be useful.  The most  natural
              approach would be to associate these mandatory varbinds with the
              notificationEvent 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,
              followed  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
       iquerySecName 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
       particular 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
              equivalent 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
       commands  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.

              In either case, the exit statement and output will be cached for
              30s after the initial query.  This cache can be flushed by a SET
              request   of   the   integer   value   1  to  the  MIB  instance
              versionClearCache.0.

       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
              number 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)  containing  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
              separate extend directives can specify  the  same  MIBOID  root,
              without conflicting.

              The   exit   status   and   output  is  cached  for  each  entry
              individually, 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-
              command(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
       convenient 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
       mechanism 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
              specified  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
              exception.

                      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
              stdout,  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
              registrations  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
       interpret perl scripts directly, thus avoiding the overhead of spawning
       processes 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
       package 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
              NetSNMP::agent object - a variable $agent which can be  used  to
              register 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
              absolute   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/lib/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
       different 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
       appropriate SNMPv3 context in the incoming request (or  using  suitable
       configured 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
              authenticated  using  the  password  PASS.   If  a  subagent (or
              "peer") connects to the agent and registers  this  subtree  then
              requests for OIDs within it will be passed to that SMUX subagent
              for processing.

              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
       master 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/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
              perform  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
       (possibly 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
                     table_iterator

                     If you want  a  table  to  play  with,  try  walking  the
                     nsModuleTable 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
                     properly  (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
              snmpwalk  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
              configuration   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
              feature 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),
       EXAMPLE.conf, read_config(3).