snmpd(ADMN)

snmpd -- SNMP daemon

Syntax

/etc/snmpd [ -v log_level ]

Description

snmpd is the Internet Simple Network Management Protocol (SNMP) server process. It is also commonly referred to as the SNMP agent. It also functions as an SMUX server. This process listens on the UDP port 161, (specified in the ``snmp'' service specification) for incoming SNMP requests. snmpd also listens on the TCP port 199 (specified in the ``smux'' service specification) for incoming connect requests from the SMUX peers and various other TCP end-points connected to SMUX peers to exchange SMUX PDUs. For service specifications see services(SFF).

snmpd uses four configuration files. They are /etc/snmpd.conf, /etc/snmpd.comm, /etc/snmpd.trap, and /etc/snmpd.peers. /etc/snmpd.conf is read to initialize the elements in the system group and the SMUX reserved subtrees. The two files /etc/snmpd.comm and /etc/snmpd.trap are used to initialize the lists of systems in the communities that will be allowed to access the Management Information Base on the local system. /etc/snmpd.peers is used to authenticate open requests from potential SMUX peers. See snmpd.conf(SFF), snmpd.comm(SFF), snmpd.trap(SFF) and snmpd.peers(SFF) for more information on the formats and uses of these files.

snmpd, by default, logs information regarding its operation to its log file /usr/adm/snmpd.log. If the -v option is specified on the snmpd command line, snmpd logs this information to standard output instead of its log file. You can select the amount and kind of information which snmpd logs by specifying one of four log levels (0, 1, 2, or 3). The lowest level (0) logs minimal information, while each higher level adds more information to what is logged by the lower levels. When invoked without the -v option, snmpd logs at the lowest level (0). When specifying the -v option, the user must set the log_level to 0, 1, 2, or 3. After snmpd is invoked, the log_level can be increased or decreased by sending it the signals SIGUSR1 and SIGUSR2, respectively (see ``Signal processing'' below).

The SNMP agent generates Trap PDUs when it notices any exceptional conditions. The /etc/snmpd.trap file is used to determine the recipients of these messages.

When the SNMP agent starts up, it generates a coldStart trap PDU. It also generates a coldStart trap PDU whenever it is re-configured. It generates a warmStart trap PDU whenever it reinitializes itself with no changes in its configuration. It generates linkUp and linkDown trap PDUs whenever an interface comes up or goes down, respectively. It generates an authenticationFailure trap PDU whenever it receives a packet which fails the authentication check.

Signal processing

snmpd catches the following signals and does special processing.

SIGHUP: Causes snmpd to re-read the configuration files. snmpd performs a clean-up of all the previously allocated data structures if it has successfully re-read the configuration files. Upon successful re-configuration, the agent generates a coldStart trap.
SIGUSR1: Raises the log level by one, increasing the amount of log information output to the log file or standard output.
SIGUSR2: Lowers the log level by one, decreasing the amount of log information output to the log file or standard output.

Files

/etc/snmpd.conf
/etc/snmpd.comm
/etc/snmpd.trap
/etc/snmpd.peers
/usr/adm/snmpd.log

Standards conformance

snmpd is conformant with: