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The module snmp_mgr provides a simple SNMP (Simple
Network Management Protocol) manager. It is used for test
purposes during agent development. There are two modes of
operation. First, it can be used as a simple command line
manager. Second, it can be used to write test suites for testing
the MIB implementation in the SNMP agent.
The manager supports SNMPv1, SNMPv2c and SNMPv3, including authentication and privacy.
The command line manager uses the Erlang shell. It supports all
SNMPv1, v2 and v3 requests, i.e. set, get,
get-next and get-bulk. For example,
snmp_mgr:s([{[1,2,3,0],
"hej"}]), sends a set request to the agent and
snmp_mgr:g([[1,2,3,0], [myVar,0]]) gets two values. The
manager operates asynchronously. This implies that the return
value of most functions is nonsense. When the manager gets a
response message from the agent, it is echoed to the display.
The start-up option quiet tells the manager not to display
incoming SNMP responses, traps and informs. Messages are sent
to the Erlang process that started the manager.
This makes it possible to process them from an application or a test
suite.
Use the expect function (that operates on the message queue) to
write test suites. Examples of how to write a test suite can
be found in snmp_mgr_tests.erl.
MIBs (Management Information Base) can be loaded in the manager.
There are two reasons for doing this. OBJECT IDENTIFIERs (Oids) can
be entered in symbolic form. Example: instead of [1,3,6,1,2,1,1,1], the
symbolic name sysDescr can be used. The other reason is to take
advantage of the type information in the MIB when sending set
requests.
An Oid is represented as a list. For convenience,
nested lists are allowed. There is one exception though. If an
oid is entered in symbolic form, this symbol must be the first
item in the list. A symbolic name includes the complete path
from the top of the global naming tree. Accordingly, an oid can
only contain one symbolic name.
Examples of valid Oids are: [myVar, 0], [1,2,3,4,5,0], [myColumn, 95], [myTable, 4, 123, [5|"eklas"]].
The last example refers to column 4 of the row with the two keys 123 and [5|"eklas"] of table myTable.
Known bug: There is not yet a {timeout, Msecs} option.
expect(Id, What) -> ok | {error, Id, Reason}
expect(Id, ErrorStatus,ErrorIndex,Varbinds)
expect(Id, trap, Enterp, Generic, Specific, Varbinds)
expect(Id, v2trap, Varbinds)
expect(Id, report, Varbinds)
expect(Id, {inform, InformReply}, Varbinds)
Types:
Id = term()
What = any|trap|timeout|Varbinds|ErrorStatus
ErrorIndex = integer()
Enterp = oid()
Generic = integer()
Specific = integer()
InformReply = true | false | {error, ErrorStatus, ErrorIndex}
Id is used to help identifying this
particular test in a long test suite. It is not used by
the manager.
any makes the test succeed for any response.
timeout succeeds if the message queue is
empty for 3.5 seconds.
This can be used to ensure that no messages are pending.
ErrorStatus is an atom which describes an error
message. See documentation for the SNMP agent.
Varbinds is a list of {Oid, Value}|{Oid,any}.
If a response other than the expected one is received, an
error message is displayed and and {error, Id,
Reason} is returned. A call to expect is
normally directly preceeded by sending a message.
The reply to a received Inform request can be controlled.
If InformReply is true, a noError reply is
sent. If it is false no reply is sent. If it is {error,
ErrorStatus, ErrorIndex}, a reply indicating the error is sent.
Types:
Oids = [oid()]
Sends a get-request.
gb(NonRepeaters, MaxRepetitions, Oids) -> void()
Types:
NonRepeaters = integer()
MaxRepetitions = integer()
Oids = [oid()]
Sends a get-bulk-request (See RFC1905).
Types:
Oids = [oid()]
Sends a get-next-request.
Sends yet another get-next-request constructed from the previous response. This is a nice feature for manually traversing a MIB.
Types:
N = integer()
Sends N get-next-request requests.
The last response is used as the start value.
Works somewhat like a get-bulk-request (see SNMPv2).
oid_to_name(Oid) -> {ok, Name} | {error, Reason}
Types:
Oid = oid()
Name = atom()
name_to_oid(Name) -> {ok, Oid} | {error, Reason}
Types:
Name = atom()
Oid = oid()
Transform a aliasname to it's oid.
Types:
Varbinds = [varbind()]
Sends a set-request.
Varbind is:
Oid is loaded
by the manager.
s|o|i (String, Oid, Integer).
This syntax is used if this object is not defined in a
MIB loaded by the manager. (Or if you explicitly want to
send a request of wrongly typed data.)
start(Options)
start_link(Options) -> void()
Types:
Options = [options()]
Starts the SNMP manager.
Mandatary options are:
{agent_udp, int()} - the UDP port that the agent
listens to. Default is 4000.
{trap_udp, int()} - the UDP port where the manager
will receive traps. Default is 5000.
{community, string()} - the community string that
is sent in the requests from the manager. Default is "public".
{context, string()} - the context that is
sent in v3 requests from the manager. Default is "".
{user, string()} - the USM user name that
is sent in v3 requests from the manager. Default is "initial".
{engine_id, string()} - the engine ID of the
agent. Used in v3 only. Default is "agentEngine".
{context_engine_id, string()} - the context
engine ID used in v3 requests. Default is the same as
engine_id.
{sec_level, noAuthNoPriv + authNoPriv | authPriv} -
the requested security level. Used in v3 only. Default is
noAuthNoPriv.
{dir, string()} - the directory where the
file usm.conf is located. This file is only
needed if v3 is used. The file has the same syntax as the
usm.conf file for the agent.
{mibs, List of filename} - MIBs to be loaded in the
manager. Default is no MIBs. The MIBs must be compiled.
{receive_type, pdu | msg} - defines the
format of delivered messages. Default is pdu.
quiet - incoming responses are not displayed.
receive_type. If the value is
pdu (default),the message is {snmp_pdu, PDU} where
PDU is a pdu() or a trappdu() record defined in
snmp_types.hrl. If the value is msg, the message
is {snmp_msg, Msg, Ip, Udp}. If the request was issued
with an erroneous oid, the message is {oid_error, Reason}, where
Reason is a printable string. Default is, this
option is not present, i.e. all incoming requests are
displayed. This option must be present when running test
suites.
v1|v2|v3 - what SNMP version to use. Default is v1.
{recbuf, integer()} - defines the
size of a UDP socket receive buffer.
1024.
Stops the SNMP manager.