Simple Network Management Protocol
daemon configuration file
snmpd.conf is the configuration file for
the snmpd(8) daemon.
snmpd.conf file is divided into three
- User-defined variables may be defined and 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:
Macros can be defined that will later be expanded in context.
Macro names must start with a letter, digit, or underscore, and may contain
any of those characters. Macro names may not be reserved words (for example,
oid). Macros are not expanded inside quotes.
ext_addr="192.168.0.1" listen on $ext_addr
The following options can be set globally:
- 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
- Specify the local address snmpd(8) should listen on for incoming SNMP messages.
- Specify the name of the read-only community. The default value is public.
- Specify the name of the read-write community, or disallow writes completely. The default value is private.
- Specify the lowest security level that
- Both authentication and encryption of messages is optional. This is the default value.
- Authentication of messages is mandatory. snmpd(8) will discard any messages that don't have a valid digest. Encryption of messages is optional.
- Messages must be encrypted and must have a valid digest for authentication. Otherwise they will be discarded.
If the chosen value is different from
nonesnmpd(8) will accept only SNMPv3 requests since older versions neither support authentication nor encryption.
- Create a control socket at path. If
restrictedis specified, a restricted control socket will be created. If
agentxis specified, a socket which speaks the AgentX protocol will be created. Multiple
agentxsockets may be created. By default /var/run/snmpd.sock is created and no other sockets are created.
- Specify the name or description of the system contact, typically a name or an e-mail address. The default value is root@hostname using the hostname of the local machine.
- Specify a description of the local system. The default value is the
operating system identification as printed by the
uname(1) command using the
OpenBSD myhost.example.com 4.2 GENERIC#595 i386
- Specify the string describing the location of the local system, typically a physical location. The default value is an empty string.
- Specify the name of the local system, typically a fully-qualified domain name. The default value is the hostname of the local system.
- Specify the authoritative identification of the local system. The default value is 22.214.171.124.4.1.30155.23.1 (iso.org.dod.internet.private.enterprises.openbsd.23.1) identifying a common OpenBSD system.
- 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.
- Specify the name of the trap community. The default value is public.
trap handleoid "command"
commandupon 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).
trap receiverstring [
- 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 using the revised SNMPv2 format and the
configured trap community. The default community is specified by the
Users for the SNMP User-based Security Model (USM, RFC 3414) must be defined in the configuration file:
- Defines a known user. The
authkeykeyword 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-sha1. If omitted the default is
enckeythe encryption key used to encrypt and decrypt messages for privacy is defined. Without an
enckeyspecification the user account will neither accept encrypted incoming messages nor will it encrypt outgoing messages. The enc algorithm can be either
aesand defaults to
Any user account that has encryption enabled requires authentication to be enabled too.
It is possible to specify user-defined OIDs in the configuration file:
read-write] [type] value
- Return the specified value to the client for this OID. The
read-writeoption may allow the client to override it, and the type is either
- Default location of the configuration file.
The following example will tell snmpd(8) to listen on localhost, override the default system OID, set the magic services value and provides some custom OID values:
listen on 127.0.0.1 system oid 126.96.36.199.4.1.30155.23.2 system services 74 oid 188.8.131.52.4.1.30155.42.1 name myName read-only string "humppa" oid 184.108.40.206.4.1.30155.42.2 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 two users, the first one is using the
encryption algorithm and the second one the default
seclevel enc user "hans" authkey "password123" enc aes enckey "321drowssap" user "sophie" authkey "password456" enckey "654drowssap"
snmpd.conf file format first appeared
in OpenBSD 4.3.
The snmpd(8) program was written by Reyk Floeter <email@example.com>.