Using the pysnmp framework i get some values doing a snmp walk. Unfortunately for the oid
1.3.6.1.21.69.1.5.8.1.2 (DOCS-CABLE-DEVICE-MIB)
i get a weird result which i cant correctly print here since it contains ascii chars like BEL ACK
When doing a repr i get:
OctetString('\x07\xd8\t\x17\x03\x184\x00')
But the output should look like:
2008-9-23,3:24:52.0
the format is called "DateAndTime". How can i translate the OctetString output to a "human readable" date/time ?
You can find the format specification here.
A date-time specification.
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 minutes 0..59
6 7 seconds 0..60
(use 60 for leap-second)
7 8 deci-seconds 0..9
8 9 direction from UTC '+' / '-'
9 10 hours from UTC* 0..13
10 11 minutes from UTC 0..59
* Notes:
- the value of year is in network-byte order
- daylight saving time in New Zealand is +13 For example,
Tuesday May 26, 1992 at 1:30:15 PM EDT would be displayed as:
1992-5-26,13:30:15.0,-4:0
Note that if only local time is known, then timezone
information (fields 8-10) is not present.
In order to decode your sample data you can use this quick-and-dirty one-liner:
>>> import struct, datetime
>>> s = '\x07\xd8\t\x17\x03\x184\x00'
>>> datetime.datetime(*struct.unpack('>HBBBBBB', s))
datetime.datetime(2008, 9, 23, 3, 24, 52)
The example above is far from perfect, it does not account for size (this object has variable size) and is missing timezone information. Also note that the field 7 is deci-seconds (0..9) while timetuple[6] is microseconds (0 <= x < 1000000); the correct implementations is left as an exercise for the reader.
[update]
8 years later, lets try to fix this answer (am I lazy or what?):
import struct, pytz, datetime
def decode_snmp_date(octetstr: bytes) -> datetime.datetime:
size = len(octetstr)
if size == 8:
(year, month, day, hour, minutes,
seconds, deci_seconds,
) = struct.unpack('>HBBBBBB', octetstr)
return datetime.datetime(
year, month, day, hour, minutes, seconds,
deci_seconds * 100_000, tzinfo=pytz.utc)
elif size == 11:
(year, month, day, hour, minutes,
seconds, deci_seconds, direction,
hours_from_utc, minutes_from_utc,
) = struct.unpack('>HBBBBBBcBB', octetstr)
offset = datetime.timedelta(
hours=hours_from_utc, minutes=minutes_from_utc)
if direction == b'-':
offset = -offset
return datetime.datetime(
year, month, day, hour, minutes, seconds,
deci_seconds * 100_000, tzinfo=pytz.utc) + offset
raise ValueError("The provided OCTETSTR is not a valid SNMP date")
I'm not sure I got the timezone offset right but I don't have sample data to test, feel free to amend the answer or ping me in the comments.
@Paulo Scardine: This was the best answer I found online when working to resolve a very similar problem. It still took me a little while to resolve my issue even with this answer, so I wanted to post a follow up answer that may add more clarity. (specifically the issue with the date having different length options).
The following piece of code connects to a server and grabs the system time and then outputs it as a string to illustrate the method.
import netsnmp
import struct
oid = netsnmp.Varbind('hrSystemDate.0')
resp = netsnmp.snmpget(oid, Version=1, DestHost='<ip>', Community='public')
oct = str(resp[0])
# hrSystemDate can be either 8 or 11 units in length.
oct_len = len(oct)
fmt_mapping = dict({8:'>HBBBBBB', 11:'>HBBBBBBcBB'})
if oct_len == 8 or oct_len == 11:
t = struct.unpack(fmt_mapping[oct_len], oct)
print 'date tuple: %s' % (repr(t))
else:
print 'invalid date format'
I hope this helps other people who are having similar issues trying to work with this type of data.
来源：https://stackoverflow.com/questions/4571899/convert-snmp-octet-string-to-human-readable-date-format