SNMPD.CONF(5) | File Formats Manual | SNMPD.CONF(5)

# NAME

`snmpd.conf` — SNMP daemon configuration file

# DESCRIPTION

`snmpd.conf` is the configuration file for the snmpd(8) daemon.

The `snmpd.conf` file is divided into the following main sections:

Macros
  Definitions of variables that can be used later, simplifying the configuration file.
Global configuration
  Global runtime settings for snmpd(8).
User configuration
  USM user definitions.
OID configuration
  Custom configuration of SNMP object identifiers and values.

The current line can be extended over multiple lines using a backslash (‘\’). Comments can be put anywhere in the file using a hash mark (‘#’), and extend to the end of the current line. Care should be taken when commenting out multi-line text: the comment is effective until the end of the entire block.

Argument names not beginning with a letter, digit, or underscore must be quoted.

Additional configuration files can be included with the `include` keyword, for example:

    include "/etc/snmpd.conf.local"

## Macros

A macro is defined with a command of the form name=value. The macro name can contain letters, digits, and underscores and cannot be a reserved word (for example, `community`, `system`, or `oid`). Within unquoted arguments, the string $name is later expanded to value.

For example:

    ext_addr="192.168.0.1"
    listen on $ext_addr

## Global configuration

The following options can be set globally:

`blocklist` oid
  Remove the oid subtree from view. Multiple `blocklist` statements are supported.
`filter-routes` (`yes` | `no`)
  If set to `yes`, ask the kernel to filter route update messages on the routing socket. Routing table information will not be available, but CPU use will be reduced during bulk updates. The default is `no`.
`listen on` [`tcp` | `udp`] address [`port` port] [flags]
  Specify the local address snmpd(8) should listen on for incoming SNMP messages, or `any` to listen on all local IPv4 and IPv6 addresses. Multiple `listen on` statements are supported. If no `listen on` statement is present, the default is `listen on` `any`.

  The flags are as follows:

  `read`
    Accept get, getnext and bulkget requests.
  `write`
    Accepts set requests.
  `notify`
    Accepts trapv1 and trapv2 requests.
  `snmpv1`
    Enable SNMPv1 subsystem on the listen address.
  `snmpv2c`
    Enable SNMPv2c subsystem on the listen address.
  `snmpv3`
    Enable SNMPv3 subsystem on the listen address.

  The default protocol is `udp`. The default port is 161, unless `notify` is the only permission flag; which sets the port to 162. If no permission flags are specified it defaults to “`read` `write`”, or `notify` when port is 162. If no subsystem flags are specified, it defaults to `snmpv3`.

  Having `notify` set requires at least one `trap handle` statement.

`agentx` [`path` path] [`owner` owner] [`group` group] [`mode` mode]
  Set up an agentx master socket at path and defaults to /var/agentx/master. Socket owner, group, and permissions can be set with owner, group, and mode respectively and defaults to root, _agentx, and 660. Multiple `agentx` statements are supported. Only unix sockets are supported.
`engineid` [`pen` enterprise] format
  Set the snmp engineid, used for instance identification and key generation for the `user` auth and key. enterprise specifies the private enterprise number of the instance and can be either an integer or `openbsd` (default).

  format can be one of the following:

  `ipv4` address
    The engineID's format identifier is set to 1 and the ipv4 address is used in the format.
  `ipv6` address
    The engineID's format identifier is set to 2 and the ipv6 address is used in the format.
  `mac` address
    The engineID's format identifier is set to 3 and the mac address is used in the format.
  `text` text
    The engineID's format identifier is set to 4 and the ASCII text is used in the format.
  `octets` octetstring
    The engineID's format identifier is set to 5 and the octetstring in hexadecimal is used in the format.
  `hosthash` [hostname]
    The engineID's format identifier is set to 129 and the first 27 bytes of the sha256 hash of the hostname are used in the format. This option is only valid for enterprise `openbsd`. If used for the local engineID, then hostname defaults to the value of hostname(1). This format is the default.
  number octetstring
    The engineID's format identifier is set to number and the octetstring in hexadecimal is used in the format. This format is only available if enterprise is not `openbsd`.
  `agentid` octetstring
    RFC1910 legacy format. octetstring must be 8 bytes (or 16 characters in hexadecimal format).
`mib directory` path
  Specify which directories to recursively search for MIB files. Multiple directories can be specified. If no directory is specified it defaults to /usr/share/snmp/mibs.
`read-only community` string
  Specify the name of the read-only community. There is no default value.
`read-write` `community` string
  Specify the name of the read-write community. There is no default value.
`seclevel` (`none` | `auth` | `enc`)
  Specify the lowest security level that snmpd(8) accepts on SNMPv3:
  `none`
    Both authentication and encryption of messages is optional.
  `auth`
    Authentication of messages is mandatory. snmpd(8) will discard any messages that don't have a valid digest. Encryption of messages is optional.
  `enc`
    Messages must be encrypted and must have a valid digest for authentication. Otherwise they will be discarded. This is the default value.
`system contact` string
  Specify the name or description of the system contact, typically a name or an email address. The default value is root@hostname using the hostname of the local machine.
`system description` string
  Specify a description of the local system. The default value is the operating system identification as printed by the uname(1) command using the `-a` flag:

      OpenBSD myhost.example.com 4.2 GENERIC#595 i386

`system location` string
  Specify the string describing the location of the local system, typically a physical location. The default value is an empty string.
`system name` string
  Specify the name of the local system, typically a fully-qualified domain name. The default value is the hostname of the local system.
`system oid` oid-string
  Specify the authoritative identification of the local system. The default value is 1.3.6.1.4.1.30155.23.1 (iso.org.dod.internet.private.enterprises.openbsd.23.1) identifying a common OpenBSD system.
`system services` number
  Specify a magic value which indicates the set of services that the local system may provide. Refer to the sysServices description in the SNMP MIB for details. The value is given in decimal.
`trap community` string
  Specify the name of the trap community. There is no default value.
`trap handle` oid "command"
  Execute `command` upon receipt of an SNMP trap that begins with a prefix of `oid`. Alternately, the string "`default`" may be used, in which case the prefix used is `1.3`. The invoked command will receive the following information about the trap on standard input, one per line, in this order: the resolved hostname of the host sending the trap, the IP address of the host sending the trap, and any variable bindings contained in the trap (the OID followed by the value, separated by a single space). This option requires at least one `listen on` statement with a `notify` flag set. Traps over SNMPv3 are currently unsupported.
`trap receiver` address [`oid` oid-string] `snmpv2c` [`community` string] [`source-address` address]
  Specify the address or FQDN of a remote trap receiver for outgoing traps sent by snmpd(8). This option may be specified multiple times. The daemon will send outgoing traps in `snmpv2c` format. The default community is specified by the global `trap community` option. The IPv4 or IPv6 source address of the traps can be enforced using
`trap receiver` address [`oid` oid-string] [`snmpv3`] `user` name [`seclevel` level] [`source-address` address]
  Specify the address or FQDN of a remote trap receiver for outgoing traps sent by snmpd(8). This option may be specified multiple times. The daemon will send outgoing traps in `snmpv3` format. `user` must point to an existing global `user`. If `seclevel` is not defined, it defaults to the global `seclevel` option. The IPv4 or IPv6 source address of the traps can be enforced using `source-address`.

## User configuration

Users for the SNMP User-based Security Model (USM, RFC 3414) must be defined in the configuration file:

`user` name [`authkey` key `auth` hmac] [`enckey` key `enc` cipher]
  Defines a known user. The `authkey` keyword is required to specify the digest key used to authenticate messages. If this keyword is omitted then authentication is disabled for this user account. Optionally the HMAC algorithm used for authentication can be specified. hmac must be either `hmac-md5`, `hmac-sha1`, `hmac-sha224`, `hmac-sha256`, `hmac-sha384`, or `hmac-sha512`. If omitted, the default is `hmac-sha1`.

  With `enckey` the encryption key used to encrypt and decrypt messages for privacy is defined. Without an `enckey` specification the user account will neither accept encrypted incoming messages nor will it encrypt outgoing messages. The enc algorithm can be either `des` or `aes` and defaults to `aes`.

  Any user account that has encryption enabled requires authentication to be enabled too.

## OID configuration

It is possible to specify user-defined OIDs in the configuration file:

`oid` oid-string `name` name [`read-only` | `read-write`] [type] value
  Return the specified value to the client for this OID. The `read-write` option may allow the client to override it, and the type is either `string` or `integer`.

# FILES

/etc/snmpd.conf
  Default location of the configuration file.
/etc/examples/snmpd.conf
  Example configuration file.

# EXAMPLES

The following example will tell snmpd(8) to listen on localhost for SNMPv2c messages only with the community “8LHQtm1QLGzk”, override the default system OID, set the magic services value, and provide some custom OID values:

    listen on 127.0.0.1 snmpv2c
    read-only community 8LHQtm1QLGzk

    system oid 1.3.6.1.4.1.30155.23.2
    system services 74

    oid 1.3.6.1.4.1.30155.42.1 name myName read-only string "humppa"
    oid 1.3.6.1.4.1.30155.42.2 name myStatus read-only integer 1

The next example will enforce SNMPv3 with authenticated and encrypted communication and the user-based security model. The configuration defines several users using varying encryption and authentication algorithms.

    seclevel enc

    user "mgmt" auth hmac-sha256 authkey "password123" enc aes enckey "321drowssap"
    user "hans" auth hmac-sha1 authkey "password456" enc aes enckey "654drowssap"
    user "sophie" auth hmac-md5 authkey "password789" enc des enckey "987drowssap"

# SEE ALSO

snmp(1), snmpd(8)

# HISTORY

The `snmpd.conf` file format first appeared in OpenBSD 4.3.

# AUTHORS

The snmpd(8) program was written by Reyk Floeter <reyk@openbsd.org>.

July 8, 2025 | Debian