Provided by: snmp_5.4.1~dfsg-7.1ubuntu6_i386 bug


       snmpusm - creates and maintains SNMPv3 users on a network entity


       snmpusm [COMMON OPTIONS] create USER [CLONEFROM-USER]
       snmpusm [COMMON OPTIONS] delete USER
       snmpusm   [COMMON  OPTIONS]  [-Ca]  [-Cx]  passwd  OLD-PASSPHRASE  NEW-
       snmpusm [COMMON OPTIONS] <-Ca | -Cx> -Ck  passwd  OLD-KEY-OR-PASSPHRASE
       snmpusm [COMMON OPTIONS] [-Ca] [-Cx] changekey [USER]


       snmpusm  is  an  SNMP  application  that  can  be  used  to  do  simple
       maintenance on the users known to an SNMP agent,  by  manipulating  the
       agent’s  User-based  Security Module (USM) table.  The user needs write
       access to the usmUserTable MIB table.  This tool can be used to create,
       delete,  clone,  and  change  the  passphrase  of users configured on a
       running SNMP agent.


       Common options for all snmpusm commands:

       -CE ENGINE-ID
              Set usmUserEngineID to be used as  part  of  the  index  of  the
              usmUserTable.  Default is to use the contextEngineID (set via -E
              or probed) as the usmUserEngineID.

       -Cp STRING
              Set the usmUserPublic value of the (new) user to  the  specified

       Options for the passwd and changekey commands:

       -Ca    Change the authentication key.

       -Cx    Change the privacy key.

       -Ck    Allows  to  use  localized  key  (must start with 0x) instead of
              passphrase.  When this option is used, either  the  -Ca  or  -Cx
              option (but not both) must also be used.


       An unauthenticated SNMPv3 user can be created using the command

              snmpusm [OPTIONS] create USER

       This  constructs  an  (inactive)  entry  in  the  usmUserTable, with no
       authentication or privacy settings.  In principle, this user should  be
       useable for ’noAuthNoPriv’ requests, but in practise the Net-SNMP agent
       will not allow such an entry to be made active.

       In order to activate this entry, it is necessary to "clone" an existing
       user, using the command

              snmpusm [OPTIONS] cloneFrom USER CLONEFROM-USER

       The  USER  entry  then  inherits  the  same  authentication and privacy
       settings (including pass phrases) as the CLONEFROM user.

       These two steps can be combined into one, by using the command

              snmpusm [OPTIONS] create USER CLONEFROM-USER

       The two forms of the create sub-command require  that  the  user  being
       created  does  not  already  exist.  The cloneFrom sub-command requires
       that the user being cloned to does already exist.

       Cloning is the only way to specify  which  authentication  and  privacy
       protocols  to  use for a given user, and it is only possible to do this
       once.  Subsequent attempts to reclone onto the same user will appear to
       succeed,  but  will  be  silently  ignored.  This (somewhat unexpected)
       behaviour is mandated by the SNMPv3 USM specifications (RFC 3414).   To
       change  the authentication and privacy settings for a given user, it is
       necessary to delete and recreate the user entry.  This is not necessary
       for  simply changing the pass phrases (see below).  This means that the
       agent must be initialized with at least one user for  each  combination
       of  authentication and privacy protocols.  See the snmpd.conf(5) manual
       page for details of the createUser configuration directive.


       A user can be deleted from the usmUserTable using the command

              snmpusm [OPTIONS] delete USER


       User profiles contain private keys that are never transmitted over  the
       wire  in  clear text (regardless of whether the administration requests
       are encrypted or not).  To change the secret key  for  a  user,  it  is
       necessary  to specify the user’s old passphrase as well as the new one.
       This uses the command

              snmpusm  [OPTIONS]  [-Ca]  [-Cx]  passwd   OLD-PASSPHRASE   NEW-
              PASSPHRASE [USER]

       After  cloning  a  new  user  entry  from the appropriate template, you
       should immediately change the new user’s passphrase.

       If USER is not specified, this command will change  the  passphrase  of
       the  (SNMPv3)  user issuing the command.  If the -Ca or -Cx options are
       specified, then only the authentication or privacy  keys  are  changed.
       If  these  options  are not specified, then both the authentication and
       privacy keys are changed.

              snmpusm [OPTIONS] [-Ca] [-Cx] changekey [USER]

       This command changes the key in a perfect-forward-secrecy compliant way
       through  a  diffie-helman  exchange.  The remote agent must support the
       SNMP-USM-DH-OBJECTS-MIB for this command to work.  The  resulting  keys
       are  printed  to  the  console  and  may  be then set in future command
       invocations using the --defAuthLocalizedKey  and  --defPrivLocalizedKey
       options  or  in  your  snmp.conf file using the defAuthLocalizedKey and
       defPrivLocalizedKey keywords.

       Note that since these keys are randomly generated  based  on  a  diffie
       helman  exchange,  they  are no longer derived from a more easily typed
       password.  They are, however, much more secure.

       To change from a localized  key  back  to  a  password,  the  following
       variant of the passwd sub-command is used:

              snmpusm  [OPTIONS]  <-Ca | -Cx> -Ck passwd OLD-KEY-OR-PASSPHRASE

       Either the -Ca or the -Cx option must be  specified.   The  OLD-KEY-OR-
       PASSPHRASE  and/or  NEW-KEY-OR-PASSPHRASE  arguments  can  either  be a
       passphrase or a localized key starting with "0x", e.g. as  printed  out
       by the changekey sub-command.


       Let’s  assume  for  our  examples  that  the  following  VACM  and  USM
       configurations lines were in the snmpd.conf file for a Net-SNMP  agent.
       These   lines   set  up  a  default  user  called  "initial"  with  the
       authentication passphrase "setup_passphrase" so that we can perform the
       initial setup of an agent:

              # VACM configuration entries
              rwuser initial
              # lets add the new user we’ll create too:
              rwuser wes
              # USM configuration entries
              createUser initial MD5 setup_passphrase DES

       Note:  the  "initial"  user’s  setup should be removed after creating a
       real user that you grant administrative privileges to  (like  the  user
       "wes" we’ll be creating in this example.

       Note: passphrases must be 8 characters minimum in length.

   Create a new user
       snmpusm  -v3  -u initial -n "" -l authNoPriv -a MD5 -A setup_passphrase
       localhost create wes initial

              Creates a new user, here named "wes" using the user "initial" to
              do  it.   "wes"  is  cloned from "initial" in the process, so he
              inherits that user’s passphrase ("setup_passphrase").

   Change the users passphrase
       snmpusm -v 3 -u wes -n "" -l  authNoPriv  -a  MD5  -A  setup_passphrase
       localhost passwd setup_passphrase new_passphrase

              After  creating  the  user "wes" with the same passphrase as the
              "initial" user, we need to change his passphrase for  him.   The
              above  command  changes  it  from  "setup_passphrase", which was
              inherited from the initial user, to "new_passphrase".

   Test the new user
       snmpget -v 3 -u wes -n  ""  -l  authNoPriv  -a  MD5  -A  new_passphrase
       localhost sysUpTime.0

              If  the above commands were successful, this command should have
              properly performed an authenticated SNMPv3 GET  request  to  the

       Now, go remove the vacm "group" snmpd.conf entry for the "initial" user
       and  you  have  a  valid  user  ’wes’  that  you  can  use  for  future
       transactions instead of initial.


       Manipulating the usmUserTable using this command can only be done using
       SNMPv3.  This command will not work with the community-based  versions,
       even if they have write access to the table.


       snmpd.conf(5), snmp.conf(5), RFC 3414