snmpa - Interface Functions to the SNMP toolkit agent

The module snmpa contains interface functions to the SNMP agent.

The following datatypes are used in the functions below:

*

oid() = [byte()]

The oid() type is used to represent an ASN.1 OBJECT IDENTIFIER.

add_agent_caps(SysORID, SysORDescr) -> SysORIndex

Types

SysORID = oid()

SysORDescr = string()

SysORIndex = integer()

This function can be used to add an AGENT-CAPABILITY statement to the sysORTable in the agent. The table is defined in the SNMPv2-MIB.

del_agent_caps(SysORIndex) -> void()

Types

SysORIndex = integer()

This function can be used to delete an AGENT-CAPABILITY statement to the sysORTable in the agent. This table is defined in the SNMPv2-MIB.

get_agent_caps() -> [[SysORIndex, SysORID, SysORDescr, SysORUpTime]]

Types

SysORIndex = integer()

SysORId = oid()

SysORDescr = string()

SysORUpTime = integer()

Returns all AGENT-CAPABILITY statements in the sysORTable in the agent. This table is defined in the SNMPv2-MIB.

get(Agent,Vars) -> Values | {error, Reason}

get(Agent,Vars,Context) -> Values | {error, Reason}

Types

Agent = pid() | atom()

Vars = [oid()]

Context = string()

Values = [term()]

Reason = {atom(), oid()}

Performs a GET operation on the agent. All loaded MIB objects are visible in this operation. The agent calls the corresponding instrumentation functions just as if it was a GET request coming from a manager.

Note that the request specific parameters (such as current_request_id) are not accessible for the instrumentation functions if this function is used.

get_next(Agent,Vars) -> Values | {error, Reason}

get_next(Agent,Vars,Context) -> Values | {error, Reason}

Types

Agent = pid() | atom()

Vars = [oid()]

Context = string()

Values = [{oid(), term()}]

Reason = {atom(), oid()}

Performs a GET-NEXT operation on the agent. All loaded MIB objects are visible in this operation. The agent calls the corresponding instrumentation functions just as if it was a GET request coming from a manager.

Note that the request specific parameters (such as snmpa:current_request_id/0 are not accessible for the instrumentation functions if this function is used.

get_symbolic_store_db() -> Db

Types

Db = term()

Retrieve the symbolic store database reference. This is used for faster access to the database using the functions: int_to_enum/3, enum_to_int/3, name_to_oid/2, oid_to_name/2.

info() -> [{Key, Value}]

info(Agent) -> [{Key, Value}]

Types

Agent = pid() | atom()

Returns a list (a dictionary) containing information about the agent. Information includes loaded MIBs, registered subagents, some information about the memory allocation.

load_mibs(Mibs) -> ok | {error, Reason}

load_mibs(Agent,Mibs) -> ok | {error, Reason}

Types

Agent = pid() | atom()

Mibs = [MibName]

MibName = string()

Reason = term()

Loads Mibs into an agent. If the agent cannot load all MIBs, it will indicate where loading was aborted. The MibName is the name of the Mib, including the path to where the compiled mib is found. For example,

          Dir = code:priv_dir(my_app) ++ "/mibs/",
          snmpa:load_mibs(snmp_master_agent, [Dir ++ "MY-MIB"]).

unload_mibs(Mibs) -> ok | {error, Reason}

unload_mibs(Agent,Mibs) -> ok | {error, Reason}

Types

Agent = pid() | atom()

Mibs = [MibName]

MibName = string()

Unloads MIBs into an agent. If it cannot unload all MIBs, it will indicate where unloading was aborted.

which_mibs() -> Mibs

which_mibs(Agent) -> Mibs

Types

Agent = pid() | atom()

Mibs = [{MibName, MibFile}]

MibName = atom()

MibFile = string()

Retrieve the list of all the mibs loaded into this agent. Default is the master agent.

whereis_mib(MibName) -> {ok, MibFile} | {error, Reason}

whereis_mib(Agent, MibName) -> {ok, MibFile} | {error, Reason}

Types

Agent = pid() | atom()

MibName = atom()

MibFile = string()

Reason = term()

Get the full path to the (compiled) mib-file.

current_request_id() -> {value, RequestId} | false

current_context() -> {value, Context} | false

current_community() -> {value, Community} | false

current_address() -> {value, Address} | false

Types

RequestId = integer()

Context = string()

Community = string()

Address = term()

Get the request-id, context, community and address of the request currently beeing processed by the agent.

Note that these functions is intended to be called by the instrumentation functions and only if they are executed in the context of the agent process (e.g. it does not work if called from a spawned process).

enum_to_int(Name,Enum) -> {value, Int} | false

enum_to_int(Db,Name,Enum) -> {value, Int} | false

Types

Db = term()

Name = atom()

Enum = atom()

Int = int()

Converts the symbolic value Enum to the corresponding integer of the enumerated object or type Name in a MIB. The MIB must be loaded.

false is returned if the object or type is not defined in any loaded MIB, or if it does not define the symbolic value as enumerated.

Db is a reference to the symbolic store database (retrieved by a call to get_symbolic_store_db/0).

int_to_enum(Name,Int) -> {value, Enum} | false

int_to_enum(Db,Name,Int) -> {value, Enum} | false

Types

Db = term()

Name = atom()

Int = int()

Enum = atom()

Converts the integer Int to the corresponding symbolic value of the enumerated object or type Name in a MIB. The MIB must be loaded.

false is returned if the object or type is not defined in any loaded MIB, or if it does not define the symbolic value as enumerated.

Db is a reference to the symbolic store database (retrieved by a call to get_symbolic_store_db/0).

name_to_oid(N) -> {value, oid()} | false

name_to_oid(Db,Name) -> {value, oid()} | false

Types

Db = term()

Name = atom()

Looks up the OBJECT IDENTIFIER of a MIB object, given the symbolic name. Note, the OBJECT IDENTIFIER is given for the object, not for an instance.

false is returned if the object is not defined in any loaded MIB.

Db is a reference to the symbolic store database (retrieved by a call to get_symbolic_store_db/0).

oid_to_name(OID) -> {value, Name} | false

oid_to_name(Db,OID) -> {value, Name} | false

Types

Db = term()

OID = oid()

Name = atom()

Looks up the symbolic name of a MIB object, given OBJECT IDENTIFIER.

false is returned if the object is not defined in any loaded MIB.

Db is a reference to the symbolic store database (retrieved by a call to get_symbolic_store_db/0).

which_aliasnames() -> Result

Types

Result = [atom()]

Retrieve all alias-names known to the agent.

which_tables() -> Result

Types

Result = [atom()]

Retrieve all tables known to the agent.

which_variables() -> Result

Types

Result = [atom()]

Retrieve all variables known to the agent.

log_to_txt(LogDir, Mibs)

log_to_txt(LogDir, Mibs, OutFile) -> ok | {error, Reason}

log_to_txt(LogDir, Mibs, OutFile, LogName) -> ok | {error, Reason}

log_to_txt(LogDir, Mibs, OutFile, LogName, LogFile) -> ok | {error, Reason}

log_to_txt(LogDir, Mibs, OutFile, LogName, LogFile, Start) -> ok | {error, Reason}

log_to_txt(LogDir, Mibs, OutFile, LogName, LogFile, Start, Stop) -> ok | {error, Reason}

Types

LogDir = string()

Mibs = [MibName]

MibName = string()

OutFile = string()

LogName = string()

LogFile = string()

Start = Stop = null | datetime() | {local_time, datetime()} | {universal_time, datetime()}

Reason = term()

Converts an Audit Trail Log to a readable text file. OutFile defaults to "./snmpa_log.txt". LogName defaults to "snmpa_log". LogFile defaults to "snmpa.log". See snmp:log_to_txt for more info.

change_log_size(N) -> ok | {error, Reason}

Types

NewSize = {MaxBytes, MaxFiles}

MaxBytes = integer()

MaxFiles = integer()

Reason = term()

Changes the log size of the Audit Trail Log. The application must be configured to use the audit trail log function. Please refer to disk_log(3) in Kernel Reference Manual for a description of how to change the log size.

The change is permanent, as long as the log is not deleted. That means, the log size is remebered across reboots.

mib_of(Oid) -> {ok, MibName} | {error, Reason}

mib_of(Agent, Oid) -> {ok, MibName} | {error, Reason}

Types

Agent = pid() | atom()

Oid = oid()

MibName = atom()

Reason = term()

Finds the mib corresponding to the Oid. If it is a variable, the Oid must be <Oid for var>.0 and if it is a table, Oid must be <table>.<entry>.<col>.<any>

me_of(Oid) -> {ok, Me} | {error, Reason}

me_of(Agent, Oid) -> {ok, Me} | {error, Reason}

Types

Agent = pid() | atom()

Oid = oid()

Me = #me{}

Reason = term()

Finds the mib entry corresponding to the Oid. If it is a variable, the Oid must be <Oid for var>.0 and if it is a table, Oid must be <table>.<entry>.<col>.<any>

register_notification_filter(Id, Mod, Data) -> ok | {error, Reason}

register_notification_filter(Agent, Id, Mod, Data) -> ok | {error, Reason}

register_notification_filter(Id, Mod, Data, Where) -> ok | {error, Reason}

register_notification_filter(Agent, Id, Mod, Data, Where) -> ok | {error, Reason}

Types

Agent = pid() | atom()

Id = filter_id()

filter_id() = term()

Mod = atom()

Data = term()

Where = filter_position()

Reason = term()

filter_position() = first | last | {insert_before, filter_id()} | {insert_after, filter_id()}

Registers a notification filter.

Mod is a module implementing the snmpa_notification_filter behaviour.

Data will be passed on to the filter when calling the functions of the behaviour.

unregister_notification_filter(Id) -> ok | {error, Reason}

unregister_notification_filter(Agent, Id) -> ok | {error, Reason}

Types

Agent = pid() | atom()

Id = filter_id()

filter_id() = term()

Unregisters a notification filter.

which_notification_filter() -> Filters

which_notification_filter(Agent) -> Filters

Types

Agent = pid() | atom()

Filters = [filter_id()]

filter_id() = term()

List all notification filters in an agent.

register_subagent(Agent,SubTreeOid,Subagent) -> ok | {error, Reason}

Types

Agent = pid() | atom()

SubTreeOid = oid()

SubAgent = pid()

Registers a subagent under a subtree of another agent.

It is easy to make mistakes when registering subagents and this activity should be done carefully. For example, a strange behaviour would result from the following configuration:

snmp_agent:register_subagent(MAPid,[1,2,3,4],SA1),
snmp_agent:register_subagent(SA1,[1,2,3], SA2).

SA2 will not get requests starting with object identifier [1, 2, 3] since SA1 does not.

unregister_subagent(Agent,SubagentOidOrPid) -> ok | {ok, SubAgentPid} | {error, Reason}

Types

Agent = pid() | atom()

SubTreeOidorPid = oid() | pid()

Unregisters a subagent. If the second argument is a pid, then that subagent will be unregistered from all trees in Agent.

send_notification(Agent,Notification,Receiver)

send_notification(Agent,Notification,Receiver,Varbinds)

send_notification(Agent,Notification,Receiver, NotifyName,Varbinds)

send_notification(Agent,Notification,Receiver, NotifyName,ContextName,Varbinds) -> void()

Types

Agent = pid() | atom()

Notification = atom()

Receiver = no_receiver | {Tag, Recv}

Tag = term()

Recv = pid() | atom() | {Mod, Func, Args}

Mod = atom()

Func = atom()

Args = list()

NotifyName = string()

ContextName = string()

Varbinds = [Varbind]

Varbind = {Variable, Value} | {Column, RowIndex, Value} | {OID, Value}

Variable = atom()

Column = atom()

OID = oid()

Value = term()

RowIndex = [int()]

Sends the notification Notification to the management targets defined for NotifyName in the snmpNotifyTable in SNMP-NOTIFICATION-MIB from the specified context. If no NotifyName is specified (or if it is ""), the notification is sent to all management targets. If no ContextName is specified, the default "" context is used.

The parameter Receiver specifies where information about delivery of Inform-Requests should be sent. The agent sends Inform-Requests and waits for acknowledgements from the managers. If the Receiver is specified as no_receiver, nothing is sent. Otherwise, it is specified as {Tag, Recv}. The receiver (Recv) gets a message:

*

{snmp_targets, Tag, Addresses}

Addresses is a list of management target addresses. If UDP over IP is used, this is a 2-tuple {IP, UDPport}, where IP is a 4-tuple with the IP address, and UDPport is an integer. The notification is sent as an Inform-Request to each target address in Addresses. If there are no targets for which an Inform-Request is sent, Addresses is the empty list [].

For each such Address is the Addresses list, one of the following two messages is sent to Recv:

*

{snmp_notification, Tag, {got_response, Address}}

*

{snmp_notification, Tag, {no_response, Address}}

The optional argument Varbinds defines values for the objects in the notification. If no value is given for an object, the Agent performs a get-operation to retrieve the value.

Varbinds is a list of Varbind, where each Varbind is one of:

*

{Variable, Value}, where Variable is the symbolic name of a scalar variable referred to in the notification specification.

*

{Column, RowIndex, Value}, where Column is the symbolic name of a column variable. RowIndex is a list of indices for the specified element. If this is the case, the OBJECT IDENTIFIER sent in the notification is the RowIndex appended to the OBJECT IDENTIFIER for the table column. This is the OBJECT IDENTIFIER which specifies the element.

*

{OID, Value}, where OID is the OBJECT IDENTIFIER for an instance of an object, scalar variable, or column variable.

For example, to specify that sysLocation should have the value "upstairs" in the notification, we could use one of:

*

{sysLocation, "upstairs"} or

*

{[1, 3, 6, 1, 2, 1, 1, 6, 0], "upstairs"} or

*

{?sysLocation_instance, "upstairs"} (provided that the generated .hrl file is included)

If a variable in the notification is a table element, the RowIndex for the element must be given in the Varbinds list. In this case, the OBJECT IDENTIFIER sent in the notification is the OBJECT IDENTIFIER that identifies this element. This OBJECT IDENTIFIER could be used in a get operation later.

This function is asynchronous, and does not return any information. If an error occurs, user_err/2 of the error report module is called and the notification is discarded.

send_trap(Agent,Trap,Community)

send_trap(Agent,Trap,Community,Varbinds) -> void()

Types

Agent = pid() | atom()

Trap = atom()

Community = string()

Varbinds = [Varbind]

Varbind = {Variable, Value} | {Column, RowIndex, Value} | {OID, Value}

Variable = atom()

Column = atom()

OID = oid()

Value = term()

RowIndex = [int()]

Note! This function is only kept for backwards compatibility reasons. Use send_notification instead.

Sends the trap Trap to the managers defined for Community in the intTrapDestTable in OTP-SNMPEA-MIB. The optional argument Varbinds defines values for the objects in the trap. If no value is given for an object, the Agent performs a get-operation to retrieve the value.

Varbinds is a list of Varbind, where each Varbind is one of:

*

{Variable, Value}, where Variable is the symbolic name of a scalar variable referred to in the trap specification.

*

{Column, RowIndex, Value}, where Column is the symbolic name of a column variable. RowIndex is a list of indices for the specified element. If this is the case, the OBJECT IDENTIFIER sent in the trap is the RowIndex appended to the OBJECT IDENTIFIER for the table column. This is the OBJECT IDENTIFIER which specifies the element.

*

{OID, Value}, where OID is the OBJECT IDENTIFIER for an instance of an object, scalar variable, or column variable.

For example, to specify that sysLocation should have the value "upstairs" in the trap, we could use one of:

*

{sysLocation, "upstairs"} or

*

{[1, 3, 6, 1, 2, 1, 1, 6, 0], "upstairs"} or

*

{?sysLocation_instance, "upstairs"} (provided that the generated .hrl file is included)

If a variable in the trap is a table element, the RowIndex for the element must be given in the Varbinds list. In this case, the OBJECT IDENTIFIER sent in the trap is the OBJECT IDENTIFIER that identifies this element. This OBJECT IDENTIFIER could be used in a get operation later.

This function is asynchronous, and does not return any information. If an error occurs, snmp_error:user_err/2 is called and the trap is discarded.

verbosity(Ref,Verbosity) -> void()

Types

Ref = pid() | sub_agents | master_agent | net_if | mib_server | symbolic_store | note_store | local_db

Verbosity = verbosity() | {subagents, verbosity()}

verbosity() = silence | info | log | debug | trace

Sets verbosity for the designated process. For the lowest verbosity silence, nothing is printed. The higher the verbosity, the more is printed.

calendar(3), erlc(1)

Micael Karlberg - support@erlang.ericsson.se