SNMP plugin HEX STRING conversion

[Heksyl]

Feature Request

Opening a feature request kicks off a discussion.

Proposal:

I would like to read and convert snmp HEX(octet) STRING values to something more readable.

Current behavior:

HEX(octet) STRINGS are not translated, not even read correctly

Desired behavior:

HEX(octet) STRINGS are translated to STRING, INT or FLOAT.

Use case: [Why is this important (helps with prioritizing requests)]

For example i have HP server related mib, which contains:

        SYNTAX  OCTET STRING (SIZE (6))
        ACCESS  read-only
        STATUS  mandatory
        DESCRIPTION
            "The time stamp when the event log entry was first created.

             field  octets  contents                  range
             =====  ======  ========                  =====
               1      1-2   year                      0..65536
               2       3    month                     1..12
               3       4    day                       1..31
               4       5    hour                      0..23
               5       6    minute                    0..59

            The year field is set with the most significant octet first.
            A value of 0 in the year indicates an unknown time stamp."
        ::= { cpqHeEventLogEntry 6 }

I would like to get those values in any readable form. Right now i get something like:

----                              ----------
1510751525000000000               ���  ```

[phemmer]

This is a really, really, obscure (and bad IMHO) way of encoding a date/time into a value.
I think there are 3 options.

1. Use hwaddr converter. This format happens to have 6 bytes, which is the same as a hardware (MAC) address. However this will format the time 2017-11-16T09:04 as 14:11:0b:10:09:04.
2. Add a converter for this specific method of encoding a date (no idea what we'd call it), and either translate it into a string, or epoch integer.
3. Some sort of generic binary to string conversion. E.G. [20,17,11,16,09,04] ([0x14,0x11,0x0b,0x10,0x09,0x04]) to the string "14 11 0b 10 09 04" (similar to hwaddr, but for arbitrary length).

@danielnelson thoughts?

[danielnelson]

I think we probably can't add a converter for this date since it is such a custom format, the best we can probably do is have a general purpose converter for binary to hex string.

[thechristschn]

I think I found another usecase for OCTET STRING to INT conversion.

I want to collect interface metrics of a fibre channel switch, which are stored inside connUnitPortStatTable (1.3.6.1.3.94.4.5) in the FCMGMT-MIB.

For example connUnitPortStatCountTxObjects counts transmitted objects, but the output is an OCTET STRING. With conversion INT, output is currently always 0.

connUnitPortStatCountTxObjects OBJECT-TYPE 
    SYNTAX OCTET STRING (SIZE (8))
    ACCESS read-only 
    STATUS mandatory 
    DESCRIPTION 
        "The number of frames/packets/IOs/etc that have been transmitted
        by this port. Note: A Fibre Channel frame starts with SOF and
        ends with EOF. FC loop devices should not count frames passed
        through. This value represents the sum total for all other Tx
        objects."
    ::= { connUnitPortStatEntry 4 }

[phemmer]

@thechristschn That's not the same as what this issue is about. For your case see the documentation on the conversion parameter: https://github.com/influxdata/telegraf/tree/release-1.5/plugins/inputs/snmp#field-parameters

[thechristschn]

@phemmer ok, then I'm sorry.
I thought the desired behavior in this request was what i meant. (At least the part when translating to INT)

Desired behavior:
HEX(octet) STRINGS are translated to STRING, INT or FLOAT.

So I guess I should open a bug, that in my case HEX STRINGS aren't converted to meaningful integers if conversion is set to INT?

[phemmer]

An octet string isn't a "hex string". Hex encoding is a method of representing an octet string, useful when the string contains binary data. This request was to perform hex encoding for such binary data. Your OID you pasted sounds like you want conversion = "int" added to your config.

[pmagos00]

@thechristschn this is the same case ... 14 years ago ...

https://cricket-users.narkive.com/jmzeDk9Q/dealing-with-snmp-datasource-in-hex

[pmagos00]

For this issue .. tested whit

#!/bin/ksh
snmpwalk -v1 -c public X.X.X.X  .1.3.6.1.3.94.4.5.1.4 | while read output;
do
index=`echo $output | cut -d "." -f 23| cut -d "=" -f 1| tr -d " \t\r"`
to_convert=`echo $output | cut -d ":" -f 4| tr -d " \t\r"`;
echo brocade,agent_host=X.X.X.X,connUnitPortStatIndex=$index,host=host   connUnitPortStatCountTxObjects=$(( 16#$to_convert ))
done

The magic is in: $(( 16#$to_convert ))

[cesarmacias]

Hi,

Its necessary to have another type of conversion, when the value are hex string like this example:

SNMPv2-SMI::enterprises.2011.6.128.1.1.2.43.1.3.4194312192.0 = Hex-STRING: 48 57 54 43 33 D9 B4 12
SNMPv2-SMI::enterprises.2011.6.128.1.1.2.43.1.3.4194312192.1 = Hex-STRING: 48 57 54 43 33 DC 70 12
SNMPv2-SMI::enterprises.2011.6.128.1.1.2.43.1.3.4194312192.2 = Hex-STRING: 48 57 54 43 33 E9 B8 12
SNMPv2-SMI::enterprises.2011.6.128.1.1.2.43.1.3.4194312192.3 = Hex-STRING: 48 57 54 43 33 EE 89 12
SNMPv2-SMI::enterprises.2011.6.128.1.1.2.43.1.3.4194312192.4 = Hex-STRING: 48 57 54 43 33 EC 24 12
SNMPv2-SMI::enterprises.2011.6.128.1.1.2.43.1.3.4194312192.5 = Hex-STRING: 48 57 54 43 33 DA F4 12

In this example the return are Serial Number, one solution is transform in string but like hwaddr with more bytes, example:
Hex-STRING: 48 57 54 43 33 DA F4 12 -> "4857544333daf412"

[MyaLongmire]

I am going to close this as snmptraslate is deprecated in telegraf and supported versions no longer use it due to performance issues and this ticket hasn't been active in a few years. If you are having issues with the recent snmp update, please open another ticket with all relevant information.