NAME¶
snmpvacm - creates and maintains SNMPv3 View-based Access Control entries on a
network entity
SYNOPSIS¶
snmpvacm [COMMON OPTIONS] AGENT
createSec2Group MODEL SECURITYNAME
GROUPNAME
snmpvacm [COMMON OPTIONS] AGENT
deleteSec2Group MODEL SECURITYNAME
snmpvacm [COMMON OPTIONS] AGENT
createView [-Ce] NAME SUBTREE MASK
snmpvacm [COMMON OPTIONS] AGENT
deleteView NAME SUBTREE
snmpvacm [COMMON OPTIONS] AGENT
createAccess GROUPNAME
[CONTEXTPREFIX] MODEL LEVEL CONTEXTMATCH READVIEW WRITEVIEW NOTIFYVIEW
snmpvacm [COMMON OPTIONS] AGENT
deleteAccess GROUPNAME
[CONTEXTPREFIX] MODEL LEVEL
snmpvacm [COMMON OPTIONS] AGENT
createAuth GROUPNAME
[CONTEXTPREFIX] MODEL LEVEL AUTHTYPE CONTEXTMATCH VIEW
snmpvacm [COMMON OPTIONS] AGENT
deleteAuth GROUPNAME
[CONTEXTPREFIX] MODEL LEVEL AUTHTYPE
DESCRIPTION¶
snmpvacm is an SNMP application that can be used to do simple maintenance
on the View-based Control Module (VACM) tables of an SNMP agent. The SNMPv3
VACM specifications (see RFC2575) define assorted tables to specify groups of
users, MIB views, and authorised access settings. These
snmpvacm
commands effectively create or delete rows in the appropriate one of these
tables, and match the equivalent configure directives which are documented in
the
snmpd.conf(5) man page.
A fuller explanation of how these operate can be found in the project FAQ.
SUB-COMMANDS¶
createSec2Group MODEL SECURITYNAME GROUPNAME¶
Create an entry in the SNMPv3 security name to group table. This table allows a
single access control entry to be applied to a number of users (or
'principals'), and is indexed by the security model and security name values.
MODEL
- An integer representing the security model, taking one of the following
values:
1 - reserved for SNMPv1
2 - reserved for SNMPv2c
3 - User-based Security Model (USM)
SECURITYNAME
- A string representing the security name for a principal (represented in a
security-model-independent format). For USM-based requests, the security
name is the same as the username.
GROUPNAME
- A string identifying the group that this entry (i.e. security name/model
pair) should belong to. This group name will then be referenced in the
access table (see createAccess below).
deleteSec2Group MODEL SECURITYNAME¶
Delete an entry from the SNMPv3 security name to group table, thus removing
access control settings for the given principal. The entry to be removed is
indexed by the MODEL and SECURITYNAME values, which should match those used in
the corresponding
createSec2Group command (or equivalent).
createView [-Ce] NAME SUBTREE MASK¶
Create an entry in the SNMPv3 MIB view table. A MIB view consists of a family of
view subtrees which may be individually included in or (occasionally) excluded
from the view. Each view subtree is defined by a combination of an OID subtree
together with a bit string mask. The view table is indexed by the view name
and subtree OID values.
[-Ce]
- An optional flag to indicate that this view subtree should be excluded
from the named view. If not specified, the default is to include the
subtree in the view. When constructing a view from a mixture of included
and excluded subtrees, the excluded subtrees should be defined first -
particularly if the named view is already referenced in one or more access
entries.
NAME
- A string identifying a particular MIB view, of which this OID subtree/mask
forms part (possibly the only part).
SUBTREE
- The OID defining the root of the subtree to add to (or exclude from) the
named view.
MASK
- A bit mask indicating which sub-identifiers of the associated subtree OID
should be regarded as significant.
deleteView NAME SUBTREE¶
Delete an entry from the SNMPv3 view table, thus removing the subtree from the
given MIB view. Removing the final (or only) subtree will result in the
deletion of the view. The entry to be removed is indexed by the NAME and
SUBTREE values, which should match those used in the corresponding
createView command (or equivalent).
When removing subtrees from a mixed view (i.e. containing both included and
excluded subtrees), the included subtrees should be removed first.
createAccess GROUPNAME [CONTEXTPREFIX] MODEL LEVEL CONTEXTMATCH READVIEW WRITEVIEW NOTIFYVIEW¶
Create an entry in the SNMPv3 access table, thus allowing a certain level of
access to particular MIB views for the principals in the specified group
(given suitable security model and levels in the request). The access table is
indexed by the group name, context prefix, security model and security level
values.
GROUPNAME
- The name of the group that this access entry applies to (as set up by a
createSec2Group command, or equivalent)
CONTEXTPREFIX
- A string representing a context name (or collection of context names)
which this access entry applies to. The interpretation of this string
depends on the value of the CONTEXTMATCH field (see below).
- If omitted, this will default to the null context "".
MODEL
- An integer representing the security model, taking one of the following
values:
1 - reserved for SNMPv1
2 - reserved for SNMPv2c
3 - User-based Security Model (USM)
LEVEL
- An integer representing the minimal security level, taking one of the
following values:
1 - noAuthNoPriv
2 - authNoPriv
3 - authPriv
- This access entry will be applied to requests of this level or higher
(where authPriv is higher than authNoPriv which is in turn higher than
noAuthNoPriv).
CONTEXTMATCH
- Indicates how to interpret the CONTEXTPREFIX value. If this field has the
value '1' (representing 'exact') then the context name of a request must
match the CONTEXTPREFIX value exactly for this access entry to be
applicable to that request.
- If this field has the value '2' (representing 'prefix') then the initial
substring of the context name of a request must match the CONTEXTPREFIX
value for this access entry to be applicable to that request. This
provides a simple form of wildcarding.
READVIEW
- The name of the MIB view (as set up by createView or equivalent)
defining the MIB objects for which this request may request the current
values.
- If there is no view with this name, then read access is not granted.
WRITEVIEW
- The name of the MIB view (as set up by createView or equivalent)
defining the MIB objects for which this request may potentially SET new
values.
- If there is no view with this name, then read access is not granted.
NOTIFYVIEW
- The name of the MIB view (as set up by createView or equivalent)
defining the MIB objects which may be included in notification
request.
- Note that this aspect of access control is not currently supported.
deleteAccess GROUPNAME [CONTEXTPREFIX] MODEL LEVEL¶
Delete an entry from the SNMPv3 access table, thus removing the specified access
control settings. The entry to be removed is indexed by the group name,
context prefix, security model and security level values, which should match
those used in the corresponding
createAccess command (or equivalent).
createAuth GROUPNAME [CONTEXTPREFIX] MODEL LEVEL AUTHTYPE CONTEXTMATCH VIEW¶
Create an entry in the Net-SNMP extension to the standard access table, thus
allowing a certain type of access to the MIB view for the principals in the
specified group. The interpretation of GROUPNAME, CONTEXTPREFIX, MODEL, LEVEL
and CONTEXTMATCH are the same as for the
createAccess directive. The
extension access table is indexed by the group name, context prefix, security
model, security level and authtype values.
AUTHTYPE
- The style of access that this entry should be applied to. See
snmpd.conf(5) and snmptrapd.conf(5) for details of valid
tokens.
VIEW
- The name of the MIB view (as set up by createView or equivalent)
defining the MIB objects for which this style of access is authorized.
deleteAuth GROUPNAME [CONTEXTPREFIX] MODEL LEVEL AUTHTYPE¶
Delete an entry from the extension access table, thus removing the specified
access control settings. The entry to be removed is indexed by the group name,
context prefix, security model, security level and authtype values, which
should match those used in the corresponding
createAuth command (or
equivalent).
Note that
snmpget REQUIRES an argument specifying the agent to query as
described in the .I
snmpcmd(1) manual page.
EXAMPLES¶
Given a pre-existing user
dave (which could be set up using the
snmpusm(1) command), we could configure full read-write access to the
whole OID tree using the commands:
- snmpvacm localhost createSec2Group 3 dave RWGroup
- snmpvacm localhost createView all .1 80
- snmpvacm localhost createAccess RWGroup 3 1 1 all all none
This creates a new security group named "RWGroup" containing the
SNMPv3 user "dave", a new view "all" containing the full
OID tree based on
.iso(1) , and then allows those users in the group
"RWGroup" (i.e. "dave") both read- and write-access to the
view "all" (i.e. the full OID tree) when using authenticated SNMPv3
requests.
As a second example, we could set up read-only access to a portion of the OID
tree using the commands:
- snmpvacm localhost createSec2Group 3 wes ROGroup
- snmpvacm localhost createView sysView system fe
- snmpvacm localhost createAccess ROGroup 3 0 1 sysView none none
This creates a new security group named "ROGroup" containing the
(pre-existing) user "wes", a new view "sysView" containing
just the OID tree based on
.iso(1).org(3).dod(6).inet(1).mgmt(2).mib-2(1).system(1) , and then
allows those users in the group "ROGroup" (i.e. "wes")
read-access, but not write-access to the view "sysView" (i.e. the
system group).
EXIT STATUS¶
The following exit values are returned:
0 - Successful completion
1 - A usage syntax error (which displays a suitable usage message) or a request
timeout.
2 - An error occurred while executing the command (which also displays a
suitable error message).
LIMITATIONS¶
This utility does not support the configuration of new community strings, so is
only of use for setting up new access control for SNMPv3 requests. It can be
used to amend the access settings for existing community strings, but not to
set up new ones.
The use of numeric parameters for
secLevel and
contextMatch
parameters is less than intuitive. These commands do not provide the full
flexibility of the equivalent config file directives.
There is (currently) no equivalent to the one-shot configure directives
rouser and
rwuser.
SEE ALSO¶
snmpcmd(1),
snmpusm(1),
snmpd.conf(5),
snmp.conf(5), RFC 2575, Net-SNMP project
FAQ