Provided by: snmp_5.2.1.2-4ubuntu2_i386 bug

NAME

       snmpusm - creates and maintains SNMPv3 users on a network entity

SYNOPSIS

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

DESCRIPTION

       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.

OPTIONS

       -Ca    Change the authentication key.

       -Cx    Change the privacy key.

       -Ck    Use old localized key instead  of  old  passphrase.   When  this
              option is used, either the -Ca or -Cx (but not both) option must
              also be used.

CREATING USERS

       An unauthenticated SNMPv3 user can be created using the command

              snmpusm 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 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 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 2474).  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.

DELETING USERS

       A user can be deleted from the usmUserTable using the command

              snmpusm delete USER

CHANGING PASS PHRASES

       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 [-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 [-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  <-Ca | -Cx> -Ck passwd OLD-LOCALIZED-KEY NEW-PASSPHRASE
              [USER]

       Either the -Ca or the -Cx option must be specified.  The OLD-LOCALIZED-
       KEY  parameter  is  the  localized  key  that  was  printed  out by the
       changekey sub-command.

EXAMPLES

       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
              agent.

       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.

WARNING

       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.

SEE ALSO

       snmpd.conf(5), snmp.conf(5), RFC 2574