snmp(3)
🌸 snmp 🌸
okay bestie, so this is snmp — the Erlang module that gives you the interface functions to the SNMP toolkit. It lives in the Erlang docs, so like… it's a module page, not a command you type in a shell. No cap. 💖
✨ NAME ✨
snmp — Interface functions to the SNMP toolkit
🦋 DESCRIPTION 🦋
The module snmp contains interface functions to the SNMP toolkit. That's literally the whole vibe. It's the front door. 🚪✨
👀 See Also
💜 DATA TYPES 💜
okay so here's the cast of characters, the whole squad, and yes we're going through all of them, don't scroll past, iykyk 🫶
algorithm() :: md5 | sha | sha224 | sha256 | sha384 | sha512.asn1_type() :: #asn1_type{}.atl_type() :: read | write | read_write.bits() :: integer().
This is the Erlang representation of the SNMP BITS (pseudo) data type. yes, "pseudo". it's giving mystery. 💅
column() :: pos_integer().community() :: snmp_community_mib:name().context_name() :: snmp_community_mib:context_name().date_and_time_validator() :: fun((Kind :: date_and_time_validator_kind(), Data :: term()) -> boolean()).
The input to the validator fun looks like this:
Kind Data
-------------- ----------------------
year {Year1, Year2}
month Month
day Day
hour Hour
minute Minute
seconds Seconds
deci_seconds DeciSeconds
diff [Sign, Hour, Minute]
valid_date {Year, Month, Day}like a little lookup table for your validator, so cute, so structured 🎀
date_and_time_validator_kind() :: year | month | day | hour | minute | seconds | deci_seconds | diff | valid_date.dir() :: string().
A string, that is a file path to a directory. paths are just strings bestie, that's it, that's the tea ☕
engine_id() :: snmp_framework_mib:engine_id().error_index() :: non_neg_integer().
0 is used when error status is noError and when error status is an actual error; error index is pos_integer/0.
error_status() :: noError | atom().
ngl this one's kind of unserious: we should really specify all of these, but they are so numerous… 👀 Also, normally all you need to know is that noError is ok and everything else is an error. simple as. periodt.
ivarbind() :: #ivarbind{}.log_size() :: infinity | pos_integer() | {MaxNoBytes :: pos_integer(), MaxNoFiles :: pos_integer()}.
This is basically a copy of the dlog_size(). (a remix, if you will 🎵)
log_time() :: calendar:datetime() | {local_time, calendar:datetime()} | {universal_time, calendar:datetime()}.me() :: #me{}.mib() :: #mib{}.mib_name() :: string().mms() :: snmp_framework_mib:max_message_size().notification() :: #notification{}.octet() :: 0..255.octet_string() :: [octet()].oid() :: [non_neg_integer()].
Represent an ASN.1 OBJECT IDENTIFIER. iconic little list of numbers 💫
pdu() :: #pdu{}.pdu_type() :: snmp_pdus:pdu_type().rfc1903_date_and_time() :: octet_string().
The data type DateAndTime, an OCTET STRING, as specified in RFC1903.
row_index() :: oid().
Denotes the last part of the OID which specifies the index of the row in the table (see RFC1212, 4.1.6 for more information about INDEX). last part = the important part, always 🔥
row_pointer() :: oid().
NOTE: "Represents a pointer to a conceptual row. The value is the name of the instance of the first accessible columnar object in the conceptual row."
OBJECT IDENTIFIER
Defined by SNMPv2-TC.
sec_level() :: snmp_framework_mib:security_level().sec_model() :: snmp_framework_mib:security_model().sec_name() :: snmp_framework_mib:admin_string().snmp_timer() :: #snmp_incr_timer{}.table_info() :: #table_info{}.taddress() :: snmpa_conf:transportAddress().tdomain() :: transportDomainUdpIpv4 | transportDomainUdpIpv6.time_interval() :: 0..2147483647.
NOTE: "A period of time, measured in units of 0.01 seconds."
INTEGER (0..2147483647)
Defined by SNMPv2-TC.
yes, hundredths of a second. chaotic unit, but slay 💅
trap() :: #trap{}.trappdu() :: #trappdu{}.usm_auth_key() :: snmp_user_based_sm_mib:auth_key().usm_auth_protocol() :: snmp_user_based_sm_mib:auth_protocol().usm_name() :: snmp_user_based_sm_mib:name().usm_priv_key() :: snmp_user_based_sm_mib:priv_key().usm_priv_protocol() :: snmp_user_based_sm_mib:priv_protocol().varbind() :: #varbind{}.variable_info() :: #variable_info{}.verbosity() :: silence | info | log | debug | trace.
For the lowest verbosity silence, nothing is printed. The higher the verbosity, the more is printed. (it's giving volume knob 📢)
version() :: v1 | v2 | v3.void() :: term().
The type is used when a function's return is to be ignored. the "no thoughts head empty" of types 🙈
💖 FUNCTIONS 💖
💫 bits_to_octet_string(B) -> octet_string() when B :: bits().
Utility function for converting a value of type BITS to OCTET-STRING, according to RFC1906, section 8. glow-up for your bits ✨
💫 change_log_size(LogName, NewSize) -> ok | {error, Reason}
when
LogName :: string(),
NewSize :: log_size(),
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 remembered across reboots. she remembers 💅
💫 config() -> ok | {error, Reason} when Reason :: term().
A simple interactive configuration tool. Simple configuration files can be generated, but more complex configurations still have to be edited manually.
The tool is a textual based tool that asks some questions and generates sys.config and *.conf files. it interviews you. gently. 🎤
Note that if the application shall support version 3, then the crypto app must be started before running this function (password generation).
Note also that some of the configuration files for the agent and manager share the same names. This means that they have to be stored in different directories!
💫 date_and_time() -> DateAndTime when DateAndTime :: rfc1903_date_and_time().
Returns current date and time as the data type DateAndTime, as specified in RFC1903. This is an OCTET STRING. it's giving "what time is it" but make it formal 🕰️
💫 date_and_time_to_string(DAT, Validate) -> string()
when
DAT :: rfc1903_date_and_time(),
Validate :: date_and_time_validator().Converts a DateAndTime list to a printable string, according to the DISPLAY-HINT definition in RFC2579.
The validation fun, Validate, allows for a more "flexible" validation of the DateAndTime argument. Whenever the data is found to not follow RFC2579, the fun is called to allow a more "lax" validation. See the validate_date_and_time/2 function for more info on the Validate fun. it's the chill parent of validators 🫶
💫 date_and_time_to_string2(DAT) -> string() when DAT :: rfc1903_date_and_time().
Converts a DateAndTime list to a printable string, according to the DISPLAY-HINT definition in RFC2579, with the extension that it also allows the values "hours from UTC" = 14 together with "minutes from UTC" = 0. the sequel that's a little more forgiving 🎬
💫 date_and_time_to_universal_time_dst(DAT) -> UTCs
when
DAT :: rfc1903_date_and_time(),
UTCs :: [calendar:datetime1970()].Converts a DateAndTime list to a list of possible universal time(s). The universal time value on the same format as defined in calendar(3). note: list of possible times. plural. timezones are messy bestie, we don't judge 😭
💫 disable_trace() -> void().
Stop the tracer. that's it. bye tracer 👋
💫 enable_trace() -> void().
Starts a dbg tracer that prints trace events to stdout (using plain io:format after a minor formatting). not me turning on the firehose 🔥
💫 local_time_to_date_and_time_dst(Local) -> DATs
when
Local :: calendar:datetime1970(),
DATs :: [rfc1903_date_and_time()].Converts a local time value to a list of possible DateAndTime list(s). The local time value on the same format as defined in calendar(3). again with the plural possibilities — DST said "i contain multitudes" 🌈
💫 log_to_io(LogDir, Mibs, LogName, LogFile, Block, Start, Stop) -> ok | {ok, Cnt} | {error, Reason}
when
LogDir :: string(),
Mibs :: [mib_name()],
LogName :: string(),
LogFile :: string(),
Block :: boolean(),
Start :: null | log_time(),
Stop :: null | log_time(),
Cnt :: {NumOK, NumERR},
NumOK :: non_neg_integer(),
NumERR :: pos_integer(),
Reason :: term().Converts an Audit Trail Log to a readable format and prints it on stdio. See log_to_txt/8 for more info. same energy, different destination 💻
💫 log_to_txt(LogDir, Mibs, OutFile, LogName, LogFile, Block, Start, Stop) -> ok | {ok, Cnt} | {error, Reason}
when
LogDir :: string(),
Mibs :: [mib_name()],
OutFile :: string(),
LogName :: string(),
LogFile :: string(),
Block :: boolean(),
Start :: null | log_time(),
Stop :: null | log_time(),
Cnt :: {NumOK, NumERR},
NumOK :: non_neg_integer(),
NumERR :: pos_integer(),
Reason :: term().Converts an Audit Trail Log to a readable text file, where each item has a trailing TAB character, and any TAB character in the body of an item has been replaced by ESC TAB. tabs on tabs on tabs, we love a formatting minute 🎀
The function can be used on a running system, or by copying the entire log directory and calling this function. SNMP must be running in order to provide MIB information. no SNMP, no MIB tea. 👑
(part 1 done — more functions incoming, don't go anywhere bestie 🫶)
okay so those arguments, one at a time bestie, no skipping 💖
LogDir— the name of the directory where the audit trail log is stored 💾Mibs— a list of Mibs to be used. It takes the info in the Mibs and converts, for example, object identifiers into their symbolic name 🏷️OutFile— the name of the generated text-file 📄LogName— the name of the logLogFile— the name of the log fileStart— the start (first) date and time from which log events will be convertedStop— the stop (last) date and time to which log events will be convertedBlock— indicates if the log should be blocked during conversion. This could be useful when converting large logs (when otherwise the log could wrap during conversion). Defaults totrue.
The format of an audit trail log text item is as follows, and yes this is literally what it looks like:
Tag Addr - Community [TimeStamp] Vsn PDUso let's unpack that, because every piece is doing something 👑
Tagisrequest,response,report,traporinformAddrisIP:Port(or a comma space separated list of such)Communityis the community parameter (SNMP version v1 and v2), orSecLevel:"AuthEngineID":"UserName"(SNMP v3)TimeStampis a date and time stampVsnis the SNMP versionPDUis a textual version of the protocol data unit
and one more lil detail — there is a new line between Vsn and PDU ✨
Now the return values, because this is where it gets interesting 👀
If the entire log is successfully converted, the function will return ok. If one or more entries fail to convert, the function will instead return {ok, {NumOK, NumERR}}, where the counters indicate how many valid and erroneous entries where found. If instead {error, Reason} is returned, the conversion encountered a fatal error and was either never done or aborted midway. 💀
octet_string_to_bits/1 🌸
octet_string_to_bits(S) -> bits() when S :: octet_string().Utility function for converting a value of type OCTET-STRING to BITS, according to RFC1906, section 8. cute, precise, does exactly one thing and slays at it 💅
passwd2localized_key/3 🔐
passwd2localized_key(Algorithm, Passwd, EngineID) -> Key
when
Algorithm :: algorithm(),
Passwd :: string(),
EngineID :: string(),
Key :: list().Generates a key that can be used as an authentication or privacy key using MD5, SHA, SHA224, SHA256, SHA384 or SHA512. The key is localized for EngineID. 🫶
print_version_info/1 🖨️
print_version_info(Prefix) -> void()
when Prefix :: string() | non_neg_integer().Utility function(s) to produce a formatted printout of the versions info generated by the versions1 function.
This is the same as doing, e.g.:
{ok, V} = snmp:versions1(),
snmp:print_versions(V).print_versions/2 📋
print_versions(Prefix, Versions) -> void()
when
Prefix :: string() | non_neg_integer(),
Versions :: [VersionInfo],
VersionInfo :: term().Utility function to produce a formatted printout of the versions info generated by the versions1 and versions2 functions.
Example:
{ok, V} = snmp:versions1(),
snmp:print_versions(V).read_mib/1 📖
read_mib(FileName) -> {ok, Mib} | {error, Reason}
when
FileName :: string(),
Mib :: mib(),
Reason :: term().Read a compiled mib. that's it, that's the whole function, and it ate ✨
reset_trace/1 🧹
reset_trace(Targets) -> void()
when Targets :: module() | [module()].This function is used to reset (disable) trace for the given module(s).
set_trace/1 🎀
set_trace(Targets) -> void()
when
Targets ::
module() |
[module() | {module(), [TargetOpt]}],
TargetOpt ::
{return_trace, boolean()} | {scope, Scope},
Scope ::
all_functions | exported_functions |
FunctionName |
{FunctionName, FunctionArity},
FunctionName :: atom(),
FunctionArity :: non_neg_integer().This function is used to set up default trace on function(s) for the given module or modules. The scope of the trace will be all exported functions (both the call info and the return value). Timestamp info will also be included. 🕐
set_trace/2 💜
set_trace(Targets, TraceOpts) -> void()
when
Targets ::
module() |
[module() | {module(), [TargetOpt]}],
TargetOpt ::
{return_trace, boolean()} | {scope, Scope},
Scope ::
all_functions | exported_functions |
FunctionName |
{FunctionName, FunctionArity},
FunctionName :: atom(),
FunctionArity :: non_neg_integer(),
TraceOpts :: disable | [TraceOpt],
TraceOpt :: {timestamp, boolean()} | TargetOpt.This function is used to set up trace on function(s) for the given module or modules.
The example below sets up trace on the exported functions (default) of module snmp_generic and all functions of module snmp_generic_mnesia. With return values (which is default) and timestamps in both cases (which is also default):
snmp:enable_trace(),
snmp:set_trace([snmp_generic,
{snmp_generic_mnesia, [{scope, all_functions}]}]),
.
.
.
snmp:set_trace(snmp_generic, disable),
.
.
.
snmp:disable_trace(),start/1 🚀
start(Type) -> ok | {error, Reason}
when
Type ::
p | permanent | tr | transient | te | temporary,
Reason :: term().Starts the SNMP application.
See application for more info.
start_agent/1 🕵️
start_agent(Type) -> ok | {error, Reason}
when
Type :: application:start_type(),
Reason :: term().The SNMP application consists of several entities, of which the agent is one. This function starts the agent entity of the application.
⚠️ Note that the only way to actually start the agent in this way is to add the agent related config after starting the application (e.g it cannot be part of the normal application config;sys.config). This is done by calling:application:set_env(snmp, agent, Conf).
The default value for Type is normal.
start_manager/1 👑🕵️
start_manager(Type) -> ok | {error, Reason}
when
Type :: application:start_type(),
Reason :: term().The SNMP application consists of several entities, of which the manager is one. This function starts the manager entity of the application.
⚠️ Note that the only way to actually start the manager in this way is to add the manager related config after starting the application (e.g it cannot be part of the normal application config;sys.config). This is done by calling:application:set_env(snmp, manager, Conf).
The default value for Type is normal.
stop/0 🛑
stop() -> ok | {error, Reason} when Reason :: term().Stops the SNMP application.
See application for more info.
This function has existed for long time, but not had a proper since tag, so to simplify we set the since tag to when it was documented. ngl iconic behavior 🙈
universal_time_to_date_and_time/1 🕰️
universal_time_to_date_and_time(UTC) -> DateAndTime
when
UTC :: calendar:datetime(),
DateAndTime ::
rfc1903_date_and_time().Converts a universal time value to a DateAndTime list. The universal time value is on the same format as defined in calendar(3). 🌈
validate_date_and_time/2 ✅
validate_date_and_time(DateAndTime, Validate) -> boolean()
when
DateAndTime ::
rfc1903_date_and_time(),
Validate ::
date_and_time_validator().Checks if DateAndTime is a correct DateAndTime value, as specified in RFC2579. This function can be used in instrumentation functions to validate a DateAndTime value.
The validation fun, Validate, allows for a more "flexible" validation of the DateAndTime argument. Whenever the data is found to not follow RFC2579, the fun is called to allow a more "lax" validation. 🫶
versions2/0 ⭐
versions2() -> {ok, VersionsInfo} | {error, Reason}
when
VersionsInfo :: [VersionInfo],
VersionInfo :: term(),
Reason :: term().Utility functions used to retrieve some system and application info.
The difference between the two functions is in how they get the modules to check. versions1 uses the app-file and versions2 uses the function application:get_key.
and that's the whole page bestie, you made it to the end 💖 this one's brought to you by Ericsson AB, snmp version 5.20.5, living in the snmp(3) manual — go forth and trace responsibly ✨🎀🦋
📦 where this page comes from
- ubuntu stonking: erlang-doc 1:29.0.6+dfsg-1 · Apache-2.0
- 💖 girlified by deepseek-ai/DeepSeek-V4.1-Flash on : a language model's rewrite of the original, under its terms