Definition of Agent Configuration Files

## 6 Definition of Agent Configuration Files

All configuration data must be included in configuration files that are located in the configuration directory. The name of this directory is given in the `config_dir` configuration parameter. These files are read at start-up, and are used to initialize the SNMPv2-MIB or STANDARD-MIB, SNMP-FRAMEWORK-MIB, SNMP-MPD-MIB, SNMP-VIEW-BASED-ACM-MIB, SNMP-COMMUNITY-MIB, SNMP-USER-BASED-SM-MIB, SNMP-TARGET-MIB and SNMP-NOTIFICATION-MIB (refer to the Management of the Agent for a description of the MIBs).

The directory where the configuration files are found is given as a parameter to the agent.

The entry format in all files are Erlang terms, separated by a '.' and a newline. In the following sections, the formats of these terms are described. Comments may be specified as ordinary Erlang comments.

Syntax errors in these files are discovered and reported with the function `config_err/2` of the error report module at start-up.

### 6.1 Agent Information

The agent information should be stored in a file called `agent.conf`.

Each entry is a tuple of size two:

`{AgentVariable, Value}.`

- `AgentVariable` is one of the variables is SNMP-FRAMEWORK-MIB or one of the internal variables `intAgentUDPPort`, which defines which UDP port the agent listens to, or `intAgentIpAddress`, which defines the IP address of the agent.
- `Value` is the value for the variable.

The following example shows a `agent.conf` file:

    {intAgentUDPPort, 4000}.
    {intAgentIpAddress,[141,213,11,24]}.
    {snmpEngineID, "mbj's engine"}.
    {snmpEngineMaxPacketSize, 484}.

The value of `snmpEngineID` is a string, which for a deployed agent should have a very specific structure. See RFC 2271/2571 for details.

### 6.2 Contexts

The context information should be stored in a file called `context.conf`. The default context `""` need not be present.

Each row defines a context in the agent. This information is used in the table `vacmContextTable` in the SNMP-VIEW-BASED-ACM-MIB.

Each entry is a term:

`ContextName.`

- `ContextName` is a string.

### 6.3 System Information

The system information should be stored in a file called `standard.conf`.

Each entry is a tuple of size two:

`{SystemVariable, Value}.`

- `SystemVariable` is one of the variables in the system group, or `snmpEnableAuthenTraps`.
- `Value` is the value for the variable.

The following example shows a valid `standard.conf` file:

    {sysDescr, "Erlang SNMP agent"}.
    {sysObjectID, [1,2,3]}.
    {sysContact, "(mbj,eklas)@erlang.ericsson.se"}.
    {sysName, "test"}.
    {sysServices, 72}.
    {snmpEnableAuthenTraps, enabled}.

A value must be provided for all variables, which lack default values in the MIB.

### 6.4 Communities

The community information should be stored in a file called `community.conf`. It must be present if the agent is configured for SNMPv1 or SNMPv2c.

The corresponding table is `snmpCommunityTable` in the SNMP-COMMUNITY-MIB.

Each entry is a term:

`{CommunityIndex, CommunityName, SecurityName, ContextName, TransportTag}.`

- `CommunityIndex` is a non-empty string.
- `CommunityName` is a string.
- `SecurityName` is a string.
- `ContextName` is a string.
- `TransportTag` is a string.

### 6.5 MIB Views for VACM

The information about MIB Views for VACM should be stored in a file called `vacm.conf`.

The corresponding tables are `vacmSecurityToGroupTable`, `vacmAccessTable` and `vacmViewTreeFamilyTable` in the SNMP-VIEW-BASED-ACM-MIB.

Each entry is one of the terms, one entry corresponds to one row in one of the tables.

`{vacmSecurityToGroup, SecModel, SecName, GroupName}.`

`{vacmAccess, GroupName, Prefix, SecModel, SecLevel, Match, ReadView, WriteView, NotifyView}.`

`{vacmViewTreeFamily, ViewIndex, ViewSubtree, ViewStatus, ViewMask}.`

- `SecModel` is `any`, `v1`, `v2c`, or `usm`.
- `SecName` is a string.
- `GroupName` is a string.
- `Prefix` is a string.
- `SecLevel` is `noAuthNoPriv`, `authNoPriv`, or `authPriv`
- `Match` is `prefix` or `exact`.
- `ReadView` is a string.
- `WriteView` is a string.
- `NotifyView` is a string.
- `ViewIndex` is an integer.
- `ViewSubtree` is a list of integer.
- `ViewStatus` is either `included` or `excluded`
- `ViewMask` is either `null` or a list of ones and zeros. Ones nominate that an exact match is used for this sub-identifier. Zeros are wildcards which match any sub-identifier. If the mask is shorter than the subtree, the tail is regarded as all ones. `null` is shorthand for a mask with all ones.

### 6.6 Security data for USM

The information about Security data for USM should be stored in a file called `usm.conf`, which must be present if the agent is configured for SNMPv3.

The corresponding table is `usmUserTable` in the SNMP-USER-BASED-SM-MIB.

Each entry is a term:

`{EngineID, UserName, SecName, Clone, AuthP, AuthKeyC, OwnAuthKeyC, PrivP, PrivKeyC, OwnPrivKeyC, Public, AuthKey, PrivKey}.`

- `EngineID` is a string.
- `UserName` is a string.
- `SecName` is a string.
- `Clone` is `zeroDotZero` or a list of integers.
- `AuthP` is a `usmNoAuthProtocol`, `usmHMACMD5AuthProtocol`, or `usmHMACSHAAuthProtocol`.
- `AuthKeyC` is a string.
- `OwnAuthKeyC` is a string.
- `PrivP` is a `usmNoPrivProtocol`, `usmDESPrivProtocol` or `usmAesCfb128Protocol`.
- `PrivKeyC` is a string.
- `OwnPrivKeyC` is a string.
- `Public` is a string.
- `AuthKey` is a list (of integer). This is the User's secret localized authentication key. It is not visible in the MIB. The length of this key needs to be 16 if `usmHMACMD5AuthProtocol` is used, and 20 if `usmHMACSHAAuthProtocol` is used.
- `PrivKey` is a list (of integer). This is the User's secret localized encryption key. It is not visible in the MIB. The length of this key needs to be 16 if `usmDESPrivProtocol` or `usmAesCfb128Protocol` is used.

### 6.7 Notify Definitions

The information about Notify Definitions should be stored in a file called `notify.conf`.

The corresponding table is `snmpNotifyTable` in the SNMP-NOTIFICATION-MIB.

Each entry is a term:

`{NotifyName, Tag, Type}.`

- `NotifyName` is a unique non-empty string.
- `Tag` is a string.
- `Type` is `trap` or `inform`.

### 6.8 Target Address Definitions

The information about Target Address Definitions should be stored in a file called `target_addr.conf`.

The corresponding tables are `snmpTargetAddrTable` in the SNMP-TARGET-MIB and `snmpTargetAddrExtTable` in the SNMP-COMMUNITY-MIB.

Each entry is a term:

`{TargetName, Ip, Udp, Timeout, RetryCount, TagList, ParamsName, EngineId}.` or
`{TargetName, Ip, Udp, Timeout, RetryCount, TagList, ParamsName, EngineId, TMask, MaxMessageSize}.`

- `TargetName` is a unique non-empty string.
- `Ip` is a list of four integers.
- `Udp` is an integer.
- `Timeout` is an integer.
- `RetryCount` is an integer.
- `TagList` is a string.
- `ParamsName` is a string.
- `EngineId` is a string.
- `TMask` is a string of size 0, or size 6 (default: []).
- `MaxMessageSize` is an integer (default: 2048).

### 6.9 Target Parameters Definitions

The information about Target Parameters Definitions should be stored in a file called `target_params.conf`.

The corresponding table is `snmpTargetParamsTable` in the SNMP-TARGET-MIB.

Each entry is a term:

`{ParamsName, MPModel, SecurityModel, SecurityName, SecurityLevel}.`

- `ParamsName` is a unique non-empty string.
- `MPModel` is `v1`, `v2c` or `v3`
- `SecurityModel` is `v1`, `v2c`, or `usm`.
- `SecurityName` is a string.
- `SecurityLevel` is `noAuthNoPriv`, `authNoPriv` or `authPriv`.

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