Conference turris::digital_unix

Mike,

Is SNMPV2 supported on UNIX 4.0B? We are interested in
using GET_BULK and the 64 bit counters

	Dave

>Mike,

>Is SNMPV2 supported on UNIX 4.0B? We are interested in
>using GET_BULK and the 64 bit counters

>	Dave

No.  v2 support arrives in the release currently called Steel.

(The code has been submitted.  If you'd like a tar-ball to try out
v2 features I'd be happy to put one together.)

Mike

Mike,

Is libesnmp thread safe? We are using esnmp in a multi threaded 
process, where the main thread is processing SNMP requests while 
another thread simultaneously might want to generate a trap.

Additional question: Are the utility functions multi-thread safe?

Thanks,
Markus

It is not explcitly thread-safe.

But I think the usage you are planning (traps fro one thread,
all other eSNP processing from another) will work.

Mike

       <<< TURRIS::DISK$NOTES_PACK2:[NOTES$LIBRARY]DIGITAL_UNIX.NOTE;1 >>>
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Note 9592.0                sequence and oid2instance()                   1 reply
TAEC::RAYBAUD                                        26 lines  23-APR-1997 04:30
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Hi,

I am trying to develop a sub-agent with the esnmp APIs and I am in trouble 
with getting back the name of the required instance value.
The instance is defined as a sequence :

ttrEntry OBJECT-TYPE
	SYNTAX TtrEntry
	ACCESS not-accessible
	STATUS mandatory
	DESCRIPTION
		"An entry in the TTRTable"
	INDEX {ttrId,ttrParentId}
	::={ttrTable 1}

ttrId is INTEGER (0..3)
ttrParentId is DisplayString

oid2instance() returns 0 as the instance value.
Moreover, the oid received is ended by 0 and not by the instance value.

Is there a problem with esnmp when we use a sequence as the instance name ?

Regards,

sacha 

       <<< TURRIS::DISK$NOTES_PACK2:[NOTES$LIBRARY]DIGITAL_UNIX.NOTE;1 >>>
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Note 9592.1                sequence and oid2instance()                    1 of 1
SMURF::DANIELE                                       55 lines  23-APR-1997 09:08
--------------------------------------------------------------------------------
>                      <<< Note 9592.0 by TAEC::RAYBAUD >>>
>                        -< sequence and oid2instance() >-

>Hi,

>I am trying to develop a sub-agent with the esnmp APIs and I am in trouble >
>with getting back the name of the required instance value.

The instance portion of the oid in a SNMP request could be anything.
It need not fully qualify the object identifier prefix that it
references.

For instance, if snmpd receives a a GetNext request for the oid 1.2.3.4.5,
and your subagent has registered the subtree 1.2.3, your subagent will be 
dispatched to.

>The instance is defined as a sequence :

>ttrEntry OBJECT-TYPE
>	SYNTAX TtrEntry
>	ACCESS not-accessible
>	STATUS mandatory
>	DESCRIPTION
>		"An entry in the TTRTable"
>	INDEX {ttrId,ttrParentId}
>	::={ttrTable 1}

>ttrId is INTEGER (0..3)
>ttrParentId is DisplayString

>oid2instance() returns 0 as the instance value.
>Moreover, the oid received is ended by 0 and not by the instance value.

Within your subagent, libesnmp.so finds the OBJECT in the
object table you registered that is the longest oid match with the
requested oid.  oid2instance returns the remainder when you "subtract"
the OBJECT's oid (the object identifier prefix) from the requested oid.

It could be anything.  A return value of 0 (the instance length)
means the requested oid is exactly the same as the OBJECT's oid.

>Is there a problem with esnmp when we use a sequence as the instance name ?

No.  I think you're just not understanding the basic operation of a method
routine.  oid2instance tells you what the requested instance was (with
respect to the OBJECT pointed to in the METHOD).  You need to figure out
if you can return something, and if so, what its instance value should be.

Have you read the chapter on eSNMP in Network Programming?

I'm going to move these notes to be replies to 1315.  Please follow up
there.

Regards,
Mike

    Hi,
    
My SNMP programs compile and run successfully when linked with

   cxx  <various .o files> -lesnmp -lutil

but when linked with pthreads:

   cxx  <various .o files> -lesnmp -lutil -lpthread

will either fail by freezing completely when a trap is generated by an
SNMP request (even CTRL-C does not interrupt) or give an error straight
away:
    
   DECthreads Last Chance handler: thread 2 exiting on status exception
0x177db005
   Exception: Invalid memory address (dce / thd)

I have also tried compiling all the programs as directed in the man page
for pthread, using -pthread on the compiler line and -lpthread -lmach
-lexc -lc on the linker line.

While this could be a coding error on my part, I need to know whether
SNMP is capable of being used with threads. That is, is it "thread
safe"?
    
    Any ideas would be very much appreciated.
    
    Thanks
    ewan smith - uk csc

libesnmp.so is not explicitly thread-safe.

But I believe other programmers have developed eSNMP subagents
that do use pthreads, and confine their eSNMP usage to a
particular thread.

I'd assume you have a programming error.

Mike

    Is it possible to multicast an SNMP pdu?
    
    eg. multicast a single SNMP set to multiple systems?
    
    Thanks,
    	Stuart.

>    Is it possible to multicast an SNMP pdu?
 
>    eg. multicast a single SNMP set to multiple systems?
    
If you mean IP Multicast, then "no".  The agent would have to specifically
bind UDP 161 to multicast groups, and I strongly doubt that many
do so.  Ours doesn't.

If you're using the term "multicast" more loosely, I guess the
answer is "yes".  An application could build an SNMP message, then
send it to lots of different agents.  (This is how most
netman apps check the status of all systems on their map, etc).

The same access control and view of managed objects would have to
exist on all nodes receiving the SNMP request.  (This might be a reasonable 
assumption for say, reading the system group using community "public".
It's probably not a reasonable assumption for issuing Sets.)

If you're asking "does Digital UNIX have any tools that do this
out of the box", the answer is "no".

Hope this helps,
Mike

    I meant IP multicast, so you've answered my question.
    
    Thanks,
    	Stuart.