Re: how can I get the time when trap happened

2012/2/1 朱飞 <[email protected]>:
> In the standard of snmp trap, time is sent on sysUpTime which is the time
> since snmp agent initialized, but how can I get the time when trap happened,
> like "2012-1-31 8:57:47.24"?

The first thing to realise is that the box sending the trap may
well not know what the current "wall clock" time actually is
when it sends the trap message.
   SNMP was originally designed to be as simple as possible
(so it could be used to monitor small embedded systems,
as well as general purpose computers).   One of the decisions
was deliberately *not* to use wall-clock timestamps within the
protocol - since this would require every box being monitored
to be configured with the current time, whenever it was
powered on.


One approach would be to use the time that you *received* the trap
(which is likely to be very soon after the trap was sent).
The trap receiver is typically a general purpose system, which will
have this information - even if the network boxes sending the traps
may not.

An alternative would be to query the box for:
    a)  the current value of sysUpTime.0,  and
    b)  the current value of hrSystemDate.0   (if available)

This would then allow you to calculate the base date-and-time
when the agent last started, and hence map the trap's
sysUpTime.0 into a wall-clock time.   Note that this will be
the time from the point of view of the sending box, rather
than the notification receiver.    In a large network (e.g. one
covering several countries),  these may well be in different
timezones, and hence the reported times could appear different.


If you can control the code that generates the trap, it might
even be possible to include hrSystemDate.0 in the payload
varbind list,  which would give you the sending date/time
information immediately.

Dave

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