Ubuntu Manpage: snmp.conf - configuration files for the Net-SNMP applications

Provided by: libsnmp-base_5.9.4+dfsg-2ubuntu1_all

NAME

       snmp.conf - configuration files for the Net-SNMP applications

DESCRIPTION

       Applications  built using the Net-SNMP libraries typically use one or more configuration files to control
       various aspects of their operation.  These files (snmp.conf and snmp.local.conf) can be located in one of
       several locations, as described in the snmp_config(5) manual page.

       In particular, /etc/snmp/snmp.conf is a common file, containing the settings shared by all users  of  the
       system.  ~/.snmp/snmp.conf is a personal file, with the settings specific to a particular user.

HOST-SPECIFIC FILES

       Host-specific  files  may  also  be loaded and will be searched for if a transport name is specified that
       matches a PATH/hosts/HOST.conf file.  For example, if you wanted a particular  host  to  use  SNMPv2c  by
       default you could create a ~/.snmp/hosts/NAME.conf file and in it put:

              defVersion 2c

       Any connections set to connect to the hostname NAME will use SNMPv2c.  Also see the transport token below
       for additional host-specific examples.

       Host-specific  configuration  files  are  loaded  at  the  time  the  connection is opened.  Thus they're
       generally loaded after all other configuration files and can  be  used  to  override  settings  from  the
       generic files.

       To avoid loading any host-specific config files set "dontLoadHostConfig true" in your snmp.conf file.

COMMAND-LINE OPTIONS

       All of the tokens described in this file can be used on the command line of Net-SNMP applications as well
       by  prefixing  them with "--".  EG, specifying --dontLoadHostConfig=true on the command line will turn of
       loading of the host specific configuration files.

IMPORTANT NOTE

       Several of these directives may contain sensitive information  (such  as  pass  phrases).   Configuration
       files that include such settings should only be readable by the user concerned.

       As  well  as  application-specific  configuration  tokens,  there  are  several directives that relate to
       standard library behaviour, relevant to most Net-SNMP applications.  Many of these correspond to standard
       command-line options, which are described in the snmpcmd(1) manual page.

       These directives can be divided into several distinct groups.

CLIENT BEHAVIOUR

defDomain application domain
The transport domain that should be used for a certain application type unless something else is
specified.

defTarget application domain target
The target that should be used for connections to a certain application if the connection should
be in a specific domain.

defaultPort PORT
defines the default UDP port that client SNMP applications will attempt to connect to. This can
be overridden by explicitly including a port number in the AGENT specification. See the
snmpcmd(1) manual page for more details.

If not specified, the default value for this token is 161.

transport HOSTSPECIFIER
This special token should go into a hostname-specific configuration file in a hosts sub-directory.
For example if the file hosts/foo.conf exists in the search path it will be loaded if a transport
name of foo was used. Within the foo.conf file you may put both general snmp.conf settings as
well as a special transport string to specify the destination to connect to. For example,
putting:

transport tcp:foo.example.com:9876

in the hosts/foo.conf file will make applications referencing the foo hostname (e.g. snmpget) to
actually connect via TCP to foo.exmaple.com on port 9876.

defVersion (1|2c|3)
defines the default version of SNMP to use. This can be overridden using the -v option.

defCommunity STRING
defines the default community to use for SNMPv1 and SNMPv2c requests. This can be overridden
using the -c option.

alias NAME DEFINITION
Creates an aliased tied to NAME for a given transport definition. The alias can the be referred
to using an alias: prefix. Eg, a line of "alias here udp:127.0.0.1:6161" would allow you to use a
destination host of "alias:here" instead of "udp:127.0.0.1:6161". This becomes more useful with
complex transport addresses involving IPv6 addresses, etc.

dumpPacket yes
defines whether to display a hexadecimal dump of the raw SNMP requests sent and received by the
application. This is equivalent to the -d option.

doDebugging (1|0)
turns on debugging for all applications run if set to 1.

debugTokens TOKEN[,TOKEN...]
defines the debugging tokens that should be turned on when doDebugging is set. This is equivalent
to the -D option.

16bitIDs yes
restricts requestIDs, etc to 16-bit values.

The SNMP specifications define these ID fields as 32-bit quantities, and the Net-SNMP library
typically initialises them to random values for security. However certain (broken) agents cannot
handle ID values greater than 2^16 - this option allows interoperability with such agents.

clientaddr [<transport-specifier>:]<transport-address>
specifies the source address to be used by command-line applications when sending SNMP requests.
See snmpcmd(1) for more information about the format of addresses.

This value is also used by snmpd when generating notifications.

clientaddrUsesPort no
specifies, if clientaddr option contains a port number. Set this option to "yes", if clientaddr
contains a port number and this port should be used for sending outgoing SNMP requests. This
option only affects IPv4 client addresses and is ignored for IPv6 client addresses.

clientRecvBuf INTEGER
specifies the desired size of the buffer to be used when receiving responses to SNMP requests. If
the OS hard limit is lower than the clientRecvBuf value, then this will be used instead. Some
platforms may decide to increase the size of the buffer actually used for internal housekeeping.

This directive will be ignored if the platforms does not support setsockopt().

clientSendBuf INTEGER
is similar to clientRecvBuf, but applies to the size of the buffer used when sending SNMP
requests.

noRangeCheck yes
disables the validation of varbind values against the MIB definition for the relevant OID. This
is equivalent to the -Ir option.

This directive is primarily relevant to the snmpset command, but will also apply to any
application that calls snmp_add_var() with a non-NULL value.

noTokenWarnings
disables warnings about unknown config file tokens.

reverseEncodeBER (1|yes|true|0|no|false)
controls how the encoding of SNMP requests is handled.

The default behaviour is to encode packets starting from the end of the PDU and working backwards.
This directive can be used to disable this behaviour, and build the encoded request in the (more
obvious) forward direction.

It should not normally be necessary to change this setting, as the encoding is basically the same
in either case - but working backwards typically produces a slightly more efficient encoding, and
hence a smaller network datagram.

dontLoadHostConfig (1|yes|true|0|no|false)
Specifies whether or not the host-specific configuration files are loaded. Set to "true" to turn
off the loading of the host specific configuration files.

retries INTEGER
Specifies the number of retries to be used in the requests.

timeout INTEGER
Specifies the timeout in seconds between retries.

SNMPv1/SNMPv2c SETTINGS

       disableSNMPv1  (1|yes|true|0|no|false)

       disableSNMPv2c (1|yes|true|0|no|false)
              Disables  protocol  versions  at  runtime.  Incoming and outgoing packets for the protocol will be
              dropped.

SNMPv3 SETTINGS

disableSNMPv3 (1|yes|true|0|no|false)
Disables protocol versions at runtime. Incoming and outgoing packets for the protocol will be
dropped.

defSecurityName STRING
defines the default security name to use for SNMPv3 requests. This can be overridden using the -u
option.

defSecurityLevel noAuthNoPriv|authNoPriv|authPriv
defines the default security level to use for SNMPv3 requests. This can be overridden using the
-l option.

If not specified, the default value for this token is noAuthNoPriv.

Note: authPriv is only available if the software has been compiled to use the OpenSSL libraries.

defPassphrase STRING

defAuthPassphrase STRING

defPrivPassphrase STRING
define the default authentication and privacy pass phrases to use for SNMPv3 requests. These can
be overridden using the -A and -X options respectively.

The defPassphrase value will be used for the authentication and/or privacy pass phrases if either
of the other directives are not specified.

defAuthType MD5|SHA|SHA-512|SHA-384|SHA-256|SHA-224

defPrivType DES|AES
define the default authentication and privacy protocols to use for SNMPv3 requests. These can be
overridden using the -a and -x options respectively.

If not specified, SNMPv3 requests will default to MD5 authentication and DES encryption.

Note: If the software has not been compiled to use the OpenSSL libraries, then only MD5
authentication is supported. Neither SHA authentication nor any form of encryption will be
available.

defContext STRING
defines the default context to use for SNMPv3 requests. This can be overridden using the -n
option.

If not specified, the default value for this token is the default context (i.e. the empty string
"").

defSecurityModel STRING
defines the security model to use for SNMPv3 requests. The default value is "usm" which is the
only widely used security model for SNMPv3.

defAuthMasterKey 0xHEXSTRING

defPrivMasterKey 0xHEXSTRING

defAuthLocalizedKey 0xHEXSTRING

defPrivLocalizedKey 0xHEXSTRING
define the (hexadecimal) keys to be used for SNMPv3 secure communications. SNMPv3 keys are
frequently derived from a passphrase, as discussed in the defPassphrase section above. However for
improved security a truely random key can be generated and used instead (which would normally has
better entropy than a password unless it is amazingly long). The directives are equivalent to the
short-form command line options -3m, -3M, -3k, and -3K.

Localized keys are master keys which have been converted to a unique key which is only suitable
for on particular SNMP engine (agent). The length of the key needs to be appropriate for the
authentication or encryption type being used (auth keys: MD5=16 bytes, SHA1=20 bytes; priv keys:
DES=16 bytes (8 bytes of which is used as an IV and not a key), and AES=16 bytes).

sshtosnmpsocket PATH
Sets the path of the sshtosnmp socket created by an application (e.g. snmpd) listening for
incoming ssh connections through the sshtosnmp unix socket.

sshtosnmpsocketperms MODE [OWNER [GROUP]]
Sets the mode, owner and group of the sshtosnmp socket created by an application (e.g. snmpd)
listening for incoming ssh connections through the sshtosnmp unix socket. The socket needs to be
read/write privileged for SSH users that are allowed to connect to the SNMP service (VACM access
still needs to be granted as well, most likely through the TSM security model).

sshusername NAME
Sets the SSH user name for logging into the remote system.

sshpubkey FILE
Set the public key file to use when connecting to a remote system.

sshprivkey FILE
Set the private key file to use when connecting to a remote system.

SERVER BEHAVIOUR

persistentDir DIRECTORY
defines the directory where snmpd and snmptrapd store persistent configuration settings.

If not specified, the persistent directory defaults to /var/lib/snmp

noPersistentLoad yes

noPersistentSave yes
disable the loading and saving of persistent configuration information.

Note: This will break SNMPv3 operations (and other behaviour that relies on changes persisting
across application restart). Use With Care.

tempFilePattern PATTERN
defines a filename template for creating temporary files, for handling input to and output from
external shell commands. Used by the mkstemp() and mktemp() functions.

If not specified, the default pattern is "/tmp/snmpdXXXXXX".

serverRecvBuf INTEGER
specifies the desired size of the buffer to be used when receiving incoming SNMP requests. If the
OS hard limit is lower than the serverRecvBuf value, then this will be used instead. Some
platforms may decide to increase the size of the buffer actually used for internal housekeeping.

This directive will be ignored if the platforms does not support setsockopt().

serverSendBuf INTEGER
is similar to serverRecvBuf, but applies to the size of the buffer used when sending SNMP
responses.

sourceFilterType none|acceptlist|blocklist
specifies whether or not addresses added with sourceFilterAddress are accepted or blocked. The
default is none, indicating that incoming packets will not be checked agains the filter list.

sourceFilterAddress ADDRESS
specifies an address to be added to the source address filter list. sourceFilterType
configuration determines whether or not addresses are accepted or blocked.

MIB HANDLING

       mibdirs DIRLIST
              specifies a list of directories to search for MIB files.  This operates in the same way as the  -M
              option  -  see  snmpcmd(1)  for  details.   Note  that this value can be overridden by the MIBDIRS
              environment variable, and the -M option.

       mibs MIBLIST
              specifies a list of MIB modules (not files) that should be loaded.  This operates in the same  way
              as  the -m option - see snmpcmd(1) for details.  Note that this list can be overridden by the MIBS
              environment variable, and the -m option.

       mibfile FILE
              specifies a (single) MIB file to load, in addition to the  list  read  from  the  mibs  token  (or
              equivalent  configuration).   Note  that  this value can be overridden by the MIBFILES environment
              variable.

       showMibErrors (1|yes|true|0|no|false)
              whether to display MIB parsing errors.

       commentToEOL (1|yes|true|0|no|false)
              whether MIB parsing should be strict about comment termination.   Many  MIB  writers  assume  that
              ASN.1  comments  extend to the end of the text line, rather than being terminated by the next "--"
              token.  This token can be used to accept such (strictly incorrect) MIBs.
              Note that this  directive  was  previous  (mis-)named  strictCommentTerm,  but  with  the  reverse
              behaviour  from  that  implied  by  the  name.  This earlier token is still accepted for backwards
              compatibility.

       mibAllowUnderline (1|yes|true|0|no|false)
              whether to allow underline characters in MIB object names and enumeration values.  This token  can
              be used to accept such (strictly incorrect) MIBs.

       mibWarningLevel INTEGER
              the minimum warning level of the warnings printed by the MIB parser.

OUTPUT CONFIGURATION

       logTimestamp (1|yes|true|0|no|false)
              Whether  the  commands  should  log timestamps with their error/message logging or not.  Note that
              output will not look as pretty with timestamps if the source code that is doing the  logging  does
              incremental  logging  of  messages  that  are not line buffered before being passed to the logging
              routines.  This option is only used when file logging is active.

       printNumericEnums (1|yes|true|0|no|false)
              Equivalent to -Oe.

       printNumericOids (1|yes|true|0|no|false)
              Equivalent to -On.

       dontBreakdownOids (1|yes|true|0|no|false)
              Equivalent to -Ob.

       escapeQuotes (1|yes|true|0|no|false)
              Equivalent to -OE.

       quickPrinting (1|yes|true|0|no|false)
              Equivalent to -Oq.

       printValueOnly (1|yes|true|0|no|false)
              Equivalent to -Ov.

       dontPrintUnits (1|yes|true|0|no|false)
              Equivalent to -OU.

       numericTimeticks (1|yes|true|0|no|false)
              Equivalent to -Ot.

       printHexText (1|yes|true|0|no|false)
              Equivalent to -OT.

       hexOutputLength integer
              Specifies where to break up the output of hexadecimal strings.  Set to 0 to disable  line  breaks.
              Defaults to 16.

       suffixPrinting (0|1|2)
              The value 1 is equivalent to -Os and the value 2 is equivalent to -OS.

       oidOutputFormat (1|2|3|4|5|6)
              Maps  -O  options  as  follow:  -Os=1, -OS=2, -Of=3, -On=4, -Ou=5.  The value 6 has no matching -O
              option. It suppresses output.

       extendedIndex (1|yes|true|0|no|false)
              Equivalent to -OX.

       noDisplayHint (1|yes|true|0|no|false)
              Disables the use of DISPLAY-HINT information when parsing indices and values to set. Equivalent to
              -Ih.

       outputPrecision PRECISION
              Uses the PRECISION string to allow modification of the value output  format.  See  snmpcmd(1)  for
              details.  Equivalent to -Op (which takes precedence over the config file).

FILES

       System-wide configuration files:
              /etc/snmp/snmp.conf
              /etc/snmp/snmp.local.conf

       User-specific configuration settings:
              $HOME/.snmp/snmp.conf
              $HOME/.snmp/snmp.local.conf

       Destination host specific files:
              /etc/snmp/hosts/HOSTNAME.conf
              $HOME/.snmp/hosts/HOSTNAME.conf