snmpusm
(1)
名前
snmpusm - creates and maintains SNMPv3 users on a network
entity
形式
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-KEY-OR-
PASSPHRASE NEW-KEY-OR-PASSPHRASE [USER]
snmpusm [COMMON OPTIONS] [-Ca] [-Cx] changekey [USER]
説明
Net-SNMP SNMPUSM(1)
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-KEY-OR-
PASSPHRASE NEW-KEY-OR-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 manipu-
lating 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
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 contex-
tEngineID (set via -E or probed) as the
usmUserEngineID.
-Cp STRING
Set the usmUserPublic value of the (new) user to the
specified STRING.
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.
CREATING USERS
An unauthenticated SNMPv3 user can be created using the com-
mand
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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 com-
mand
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 authentica-
tion 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 com-
mand
snmpusm [OPTIONS] delete USER
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CHANGING PASS PHRASES
User profiles contain private keys that are never transmit-
ted 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 tem-
plate, 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 authentica-
tion 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 com-
mand 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 fol-
lowing variant of the passwd sub-command is used:
snmpusm [OPTIONS] <-Ca | -Cx> -Ck passwd OLD-KEY-OR-
PASSPHRASE NEW-KEY-OR-PASSPHRASE [USER]
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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.
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 "set-
up_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 privi-
leges 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 set-
up_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 user's passphrase
snmpusm -v 3 -u wes -n "" -l authNoPriv -a MD5 -A set-
up_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 "set-
up_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
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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 com-
munity-based versions, even if they have write access to the
table.
ATTRIBUTES
See attributes(5) for descriptions of the following
attributes:
+---------------+-----------------------------------------------+
|ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+---------------+-----------------------------------------------+
|Availability | system/management/snmp/net-snmp/documentation |
+---------------+-----------------------------------------------+
|Stability | Volatile |
+---------------+-----------------------------------------------+
SEE ALSO
snmpd.conf(5), snmp.conf(5), RFC 3414
NOTES
This software was built from source available at
https://java.net/projects/solaris-userland. The original
community source was downloaded from
http://ftp.ntua.gr/mirror/net-snmp/OldFiles/net-
snmp-5.4.x/5.4.1/net-snmp-5.4.1.tar.gz
Further information about this software can be found on the
open source community website at http://www.net-snmp.org/.
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