Chapter 4

Configuring Enterprise Agents

4.1 Configuring Enterprise Agents Overview

The following files are considered for configuration:

Master Agent resource configuration file
Agents registration file
Agents access control file
Master Agent status file

4.2 Agents Resource Configuration Files

The Agents Resource Configuration files are used exclusively by the Master Agent. As soon as the Master Agent becomes active, it reads these files. These files store information for all those agents that the Master Agent may manage. Each entry in the configuration files also includes methods for invoking these subagents. Although a subagent might not have a configuration file, the subagent may dynamically register with the Master Agent when it becomes active. More information about dynamic invocation and registration of subagents is described in "3.2 Description of the Subagent".

Each agent may have its own resource configuration file when it opts for invocation by Master Agent and for static registration. This file contains information about the registration file associated with the subagent, in addition to the other information related to invoking the subagent. The agents registration file is described in "4.2 Agents Resource Configuration Files".

The following example shows the grammar for the resource configuration files.

<ResourceFile> : Resource | Environment Resource
<Resource> : "resource" "=" "{" ResourceList "}"
<ResourceList> : /*empty*/ | ResourceList ResourceItem
<ResourceItem> : "{" StringList "}"
<Environment> : "environment" "=" "{" EnvironmentList "}"
<EnvironmentList> : /*empty*/ | EnvironmentList
EnvironmentListItem
<EnvironmentListItem> : EnvironmentToken "=" Number
<EnvironmentToken> : "poll-interval" | "Max-agent-time-out"
<Number> : Integer
<StringList>: StringItem | StringList StringItem
<StringItem> : StringToken "=" QuotedString
<StringToken> : "registration_file" |"policy" | "command"
|'type"|"user"
<QuotedString> : """ AlphanumericString """

The following example shows the snmpdx.rsrc and mibiisa.rsrc files.

Descriptions of the variables used in the configuration file follow the example. The comment lines begin with the # character.

snmpdx.rsrc
environment =
{
poll-interval = 5 # This is in seconds
max-agent-time_out = 10000000 # This is microseconds
}

mibiisa.rsrc
resource =
{
{
registration_file = /etc/snmp/conf/mibiisa.reg
security = "/etc/snmp/conf/snmpd.conf
type = "legacy"
policy = "spawn"
command = "/usr/lib/bin/mibiisa -p $PORT"
}
}

4.2.1 Environment Group

The environment group controls the behavior of the Master Agent. This group contains the following two variables:

poll-interval - this field contains values in seconds and indicates that the Master Agent performs activities other than receiving/sending SNMP messages after the specified interval; it finds out if there is a change in the resource file (discovering if all the agents are responding) and performs other routine housekeeping activities
max-agent-time-out - the value of this field is specified in microseconds; it signifies the maximum allowed time-out a subagent may request during registration; for example, when the Master Agent sends a request to a subagent, it waits for a time_out to receive the response; this time-out may be specified in the registration file or by using dynamic registration; if an agent sets this time-out too high, it creates problems for the Master Agent and other agents; to avoid such a problem, the Master Agent must specify a maximum value for the Master Agent to wait for a response from the subagent; this maximum value of time-out is specified using this variable.

4.2.2 Resource Group

The variables in the resource group are related only to subagents. The previous example configuration file contains two entries. Each entry represents a subagent and may have the following variables with some value assigned:

type - this field has two values: legacy and dynamic.
registration_file - this field specifies the registration configuration file for each subagent. The Master Agent reads the various entries in this file and creates appropriate entries in its MIB table. The details of this file are explained in "4.3 Agents Registration File". This entry is mandatory for all legacy-type agents. If the value for this variable does not contain a full path, the executable checks the default directory /etc/snmp/conf.
policy - this field has two values: load and spawn. The value load specifies the Master Agent to read this registration entry and create a row entry in its MIB table. If it finds the value spawn, the Master Agent invokes the respective subagent, as stated in the command field of that entry.
command - this is the name of the subagent executable. The command may contain the full path, or if the full path is not mentioned, the executable checks the default directory /usr/lib/bin. The command may use a $PORT macro to provide the port number from which the subagent receives SNMP requests. $PORT is assigned a value by the Master Agent in the registration file of each subagent. The $PORT macro is necessary because the legacy agents or subagents may take different arguments for the port option (such as -p, -n, -port).
user - this subagent is run according to the user specified in this entry.