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 triggering 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 contains 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-integer 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 information 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.VERCLEARCACHE.

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 available disk space. If the disk space is less than MINSPACE (kB) if specified or less than MINPERCENT (%) if a % sign is specified, or DEFDISKMINIMUMSPACE (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 infinite 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 securitymodel/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, separated 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 relatively 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] [privpassphrase]
    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 privacy 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 characters.

    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. Multiple 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 trapcommunity directive will be used. If PORT is not specified, the well known SNMP trap port (162) will be used.

PASS-THROUGH CONTROL

pass MIBOID EXEC
    Passes entire control of MIBOID to the EXEC program. 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 getnext 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 corresponding 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 program 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 controlled by the RWRITE definition in the snmplib/snmp_impl.h source file.

EXAMPLE
See the EXAMPLE.CONF file in the top level source directory for a more detailed example of how the above information is used in real examples.

RE-READING snmpd.conf and snmpd.local.conf
The ucd-snmp agent can be forced to re-read its configuration 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 process.

FILES
share/snmp/snmpd.conf

SEE ALSO
snmp_config(5), snmpd(1), EXAMPLE.conf, read_config(3).