SNMPD.CONF(5) SNMPD.CONF(5)
NAME
share/snmp/snmpd.conf - configuration file for the ucd-
snmp SNMP agent.
DESCRIPTION
snmpd.conf is the configuration file which defines how the
ucd-smnp SNMP agent operates. These files may contain any
of the directives found in the DIRECTIVES section below.
This file is not required for the agent to operate and
report mib entries.
PLEASE READ FIRST
First, make sure you have read the snmp_config(5) manual
page that describes how the ucd-snmp configuration files
operate, where they are located and how they all work
together.
EXTENSIBLE-MIB
The ucd-snmp SNMP agent reports much of its information
through queries to the 1.3.6.1.4.1.2021 section of the mib
tree. Every mib in this section has the following table
entries in it.
.1 -- index
This is the table's index numbers for each of the
DIRECTIVES listed below.
.2 -- name
The name of the given table entry. This should be
unique, but is not required to be.
.100 -- errorFlag
This is a flag returning either the integer value 1
or 0 if an error is detected for this table entry.
.101 -- errorMsg
This is a DISPLAY-STRING describing any error trig-
gering the errorFlag above.
.102 -- errorFix
If this entry is SNMPset to the integer value of 1
AND the errorFlag defined above is indeed a 1, a
program or script will get executed with the table
entry name from above as the argument. The program
to be executed is configured in the config.h file
at compile time.
Directives
proc NAME
proc NAME MAX
proc NAME MAX MIN
Checks to see if the NAME'd processes are running
on the agent's machine. An error flag (1) and a
description message are then passed to the
1.3.6.1.4.1.2021.2.100 and 1.3.6.1.4.1.2021.2.101
mib tables (respectively) if the NAME'd program is
not found in the process table as reported by
"/bin/ps -e".
If MAX and MIN are not specified, MAX is assumed to
be infinity and MIN is assumed to be 1.
If MAX is specified but MIN is not specified, MIN
is assumed to be 0.
procfix NAME PROG ARGS
This registers a command that knows how to fix
errors with the given process NAME. When
1.3.6.1.4.1.2021.2.102 for a given NAMEd program is
set to the integer value of 1, this command will be
called. It defaults to a compiled value set using
the PROCFIXCMD definition in the config.h file.
exec NAME PROG ARGS
exec MIBNUM NAME PROG ARGS
If MIBNUM is not specified, the agent executes the
named PROG with arguments of ARGS and returns the
exit status and the first line of the STDOUT output
of the PROG program to queries of the
1.3.6.1.4.1.2021.8.100 and 1.3.6.1.4.1.2021.8.101
mib tables (respectively). All STDOUT output
beyond the first line is silently truncated.
If MIBNUM is specified, it acts as above but
returns the exit status to MIBNUM.100.0 and the
entire STDOUT output to the table MIBNUM.101 in a
mib table. In this case, the MIBNUM.101 mib con-
tains the entire STDOUT output, one mib table entry
per line of output (ie, the first line is output as
MIBNUM.101.1, the second at MIBNUM.101.2, etc...).
Note: The MIBNUM must be specified in dotted-inte-
ger notation and can not be specified as
".iso.org.dod.internet..." (should instead
be
Note: The agent caches the exit status and STDOUT
of the executed program for 30 seconds after
the initial query. This is to increase
speed and maintain consistency of informa-
tion for consecutive table queries. The
cache can be flushed by a snmp-set request
of integer(1) to 1.3.6.1.4.1.2021.100.VER-
CLEARCACHE.
execfix NAME PROG ARGS
This registers a command that knows how to fix
errors with the given exec or sh NAME. When
1.3.6.1.4.1.2021.8.102 for a given NAMEd entry is
set to the integer value of 1, this command will be
called. It defaults to a compiled value set using
the EXECFIXCMD definition in the config.h file.
disk PATH
disk PATH [ MINSPACE | MINPERCENT% ]
Checks the named disks mounted at PATH for avail-
able disk space. If the disk space is less than
MINSPACE (kB) if specified or less than MINPERCENT
(%) if a % sign is specified, or DEFDISKMINI-
MUMSPACE (kB) if not specified, the associated
entry in the 1.3.6.1.4.1.2021.9.100 mib table will
be set to (1) and a descriptive error message will
be returned to queries of 1.3.6.1.4.1.2021.9.101.
load MAX1
load MAX1 MAX5
load MAX1 MAX5 MAX15
Checks the load average of the machine and returns
an error flag (1), and an text-string error message
to queries of 1.3.6.1.4.1.2021.10.100 and
1.3.6.1.4.1.2021.10.101 (respectively) when the
1-minute, 5-minute, or 15-minute averages exceed
the associated maximum values. If any of the MAX1,
MAX5, or MAX15 values are unspecified, they default
to a value of DEFMAXLOADAVE.
file FILE [MAXSIZE]
Monitors file sizes and makes sure they don't grow
beyond a certain size. MAXSIZE defaults to infi-
nite if not specified, and only monitors the size
without reporting errors about it.
Errors
Any errors in obtaining the above information are reported
via the 1.3.6.1.4.1.2021.101.100 flag and the
1.3.6.1.4.1.2021.101.101 text-string description.
SMUX SUB-AGENTS
To enable and SMUX based sub-agent, such as gated, use the
smuxpeer configuration entry
smuxpeer OID PASS
For gated a sensible entry might be
.1.3.6.1.4.1.4.1.3 secret
ACCESS CONTROL
snmpd supports the View-Based Access Control Model (vacm)
as defined in RFC 2275. To this end, it recognizes the
following keywords in the configuration file: com2sec,
group, access, and view as well as some easier-to-use
wrapper directives: rocommunity, rwcommunity, rouser,
rwuser.
rocommunity COMMUNITY [SOURCE] [OID]
rwcommunity COMMUNITY [SOURCE] [OID]
These create read-only and read-write communities
that can be used to access the agent. They are a
quick method of using the following com2sec, group,
access, and view directive lines. They are not as
efficient either, as groups aren't created so the
tables are possibly larger. In other words: don't
use these if you have complex situations to set up.
The format of the SOURCE is token is described in
the com2sec directive section below. The OID token
restricts access for that community to everything
below that given OID.
rouser USER [noauth|auth|priv] [OID]
rwuser USER [noauth|auth|priv] [OID]
Creates a SNMPv3 USM user in the VACM access
configuration tables. Again, its more efficient
(and powerful) to use the combined com2sec, group,
access, and view directives instead.
The minimum level of authentication and privacy the
user must use is specified by the first token
(which defaults to "auth"). The OID parameter
restricts access for that user to everything below
the given OID.
com2sec NAME SOURCE COMMUNITY
This directive specifies the mapping from a
source/community pair to a security name. SOURCE
can be a hostname, a subnet, or the word "default".
A subnet can be specified as IP/MASK or IP/BITS.
The first source/community combination that matches
the incoming packet is selected.
group NAME MODEL SECURITY
This directive defines the mapping from security-
model/securityname to group. MODEL is one of v1,
v2c, or usm.
access NAME CONTEXT MODEL LEVEL PREFX READ WRITE NOTIFY
The access directive maps from group/security
model/security level to a view. MODEL is one of
any, v1, v2c, or usm. LEVEL is one of noauth,
auth, or priv. PREFX specifies how CONTEXT should
be matched against the context of the incoming pdu,
either exact or prefix. READ, WRITE and NOTIFY
specifies the view to be used for the corresponding
access. For v1 or v2c access, LEVEL will be
noauth, and CONTEXT will be empty.
view NAME TYPE SUBTREE [MASK]
The defines the named view. TYPE is either included
or excluded. MASK is a list of hex octets, sepa-
rated by '.' or ':'. The MASK defaults to "ff" if
not specified.
The reason for the mask is, that it allows you to
control access to one row in a table, in a rela-
tively simple way. As an example, as an ISP you
might consider giving each customer access to his
or her own interface:
view cust1 included interfaces.ifTable.ifEntry.ifIndex.1 ff.a0
view cust2 included interfaces.ifTable.ifEntry.ifIndex.2 ff.a0
(interfaces.ifTable.ifEntry.ifIndex.1 == .1.3.6.1.2.1.2.2.1.1.1,
ff.a0 == 11111111.10100000. which nicely covers up and including
the row index, but lets the user vary the field of the row)
VACM Examples:
# sec.name source community
com2sec local localhost private
com2sec mynet 10.10.10.0/24 public
com2sec public default public
# sec.model sec.name
group mygroup v1 mynet
group mygroup v2c mynet
group mygroup usm mynet
group local v1 local
group local v2c local
group local usm local
group public v1 public
group public v2c public
group public usm public
# incl/excl subtree mask
view all included .1 80
view system included system fe
view mib2 included .iso.org.dod.internet.mgmt.mib-2 fc
# context sec.model sec.level prefix read write notify
access mygroup "" any noauth exact mib2 none none
access public "" any noauth exact system none none
access local "" any noauth exact all all all
Default VACM model
The default configuration of the agent, as shipped, is functionally
equivalent to the following entries:
com2sec public default public
group public v1 public
group public v2c public
group public usm public
view all included .1
access public "" any noauth exact all none none
SNMPv3 CONFIGURATION
engineID STRING
The snmpd agent needs to be configured with an
engineID to be able to respond to SNMPv3 messages.
With this configuration file line, the engineID
will be configured from STRING. The default value
of the engineID is configured with the first IP
address found for the hostname of the machine.
createUser username (MD5|SHA) authpassphrase [DES] [priv-
passphrase]
This directive should be placed into the "/var/ucd-
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.
MD5 and SHA are the authentication types to use,
but you must have built the package with openssl
installed in order to use SHA. The only privacy
protocol currently supported is DES. If the pri-
vacy 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.
Warning: the minimum pass phrase length is 8 char-
acters.
SNMPv3 users can be created at runtime using the
snmpusm command.
SETTING SYSTEM INFORMATION
syslocation STRING
syscontact STRING
Sets the system location and the system contact for
the agent. This information is reported by the
'system' table in the mibII tree.
authtrapenable NUMBER
Setting authtrapenable to 1 enables generation of
authentication failure traps. The default value is
2 (disable).
trapcommunity STRING
This defines the default community string to be
used when sending traps. Note that this command
must be used prior to any of the following three
commands that are intended use this community
string.
trapsink HOST [COMMUNITY [PORT]]
trap2sink HOST [COMMUNITY [PORT]]
informsink HOST [COMMUNITY [PORT]]
These commands define the hosts to receive traps
(and/or inform notifications). The daemon sends a
Cold Start trap when it starts up. If enabled, it
also sends traps on authentication failures. Mul-
tiple trapsink, trap2sink and informsink lines may
be specified to specify multiple destinations. Use
trap2sink to send SNMPv2 traps and informsink to
send inform notifications. If COMMUNITY is not
specified, the string from a preceding trapcommu-
nity directive will be used. If PORT is not speci-
fied, the well known SNMP trap port (162) will be
used.
PASS-THROUGH CONTROL
pass MIBOID EXEC
Passes entire control of MIBOID to the EXEC pro-
gram. The EXEC program is called in one of the
following three ways:
EXEC -g MIBOID
EXEC -n MIBOID
These call lines match to SNMP get and get-
next requests. It is expected that the EXEC
program will take the arguments passed to it
and return the appropriate response through
it's stdout.
The first line of stdout should be the mib
OID of the returning value. The second line
should be the TYPE of value returned, where
TYPE is one of the text strings: string,
integer, unsigned, objectid, timeticks,
ipaddress, counter, or gauge. The third
line of stdout should be the VALUE corre-
sponding with the returned TYPE.
For instance, if a script was to return the
value integer value "42" when a request for
.1.3.6.1.4.100 was requested, the script
should return the following 3 lines:
.1.3.6.1.4.100
integer
42
To indicate that the script is unable to
comply with the request due to an end-of-mib
condition or an invalid request, simple exit
and return no output to stdout at all. A
snmp error will be generated corresponding
to the SNMP NO-SUCH-NAME response.
EXEC -s MIBOID TYPE VALUE
For SNMP set requests, the above call method
is used. The TYPE passed to the EXEC pro-
gram is one of the text strings: integer,
counter, gauge, timeticks, ipaddress, objid,
or string, indicating the type of value
passed in the next argument.
Return nothing to stdout, and the set will
assumed to have been successful. Otherwise,
return one of the following error strings to
signal an error: not-writable, or wrong-type
and the appropriate error response will be
generated instead.
Note: By default, the only community
allowed to write (ie snmpset) to
your script will be the "private"
community,or community #2 if defined
differently by the "community" token
discussed above. Which communities
are allowed write access are con-
trolled by the RWRITE definition in
the snmplib/snmp_impl.h source file.
EXAMPLE
See the EXAMPLE.CONF file in the top level source direc-
tory for a more detailed example of how the above informa-
tion is used in real examples.
RE-READING snmpd.conf and snmpd.local.conf
The ucd-snmp agent can be forced to re-read its configura-
tion files. It can be told to do so by one of two ways:
1. An snmpset of integer(1) to
1.3.6.1.4.1.2021.100.VERUPDATECONFIG.
2. A "kill -HUP" signal sent to the snmpd agent pro-
cess.
FILES
share/snmp/snmpd.conf
SEE ALSO
snmp_config(5), snmpd(1), EXAMPLE.conf, read_config(3).
27 Jan 2000 SNMPD.CONF(5)
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