Are MIB files also used for converting SNMP GetResponse *values*?

[Martin T]

Hi,

I am aware that MIB files in NMS are used to translate OID integers in
SNMP GetResponse messages into meaningful names. For example here I
can see that string "Vl290" is an VLAN-interface name:

$ snmpget -Of -v 2c -c public 10.10.10.1 .1.3.6.1.2.1.31.1.1.1.1.290
.iso.org.dod.internet.mgmt.mib-2.ifMIB.ifMIBObjects.ifXTable.ifXEntry.ifName.290
= STRING: Vl290
$


Without Cisco MIBs I would see:

$ snmpget -m /dev/null -Of -v 2c -c public 10.10.10.1
.1.3.6.1.2.1.31.1.1.1.1.290
.iso.3.6.1.2.1.31.1.1.1.1.290 = STRING: "Vl290"
$


However, are MIB files also used for converting SNMP GetResponse
values? I mean for example "snmpwalk -Ov -v 2c -c public 10.10.10.1
sysUpTimeInstance" returns "Timeticks: (88920401) 10 days,
7:00:04.01", but this conversion is done in snmpget/snmpwalk utility
itself. For example is it possible to define in MIB files that for
example 1099 integer32 value in SNMP GetResponse message should be
understood as 10cm and 99mm and then snmpget/snmpwalk utility will do
such conversions automatically? I tried to find such SNMP objects, but
did not find any.


thanks,
Martin

[Robson, Alan]

Look for display hints in, for example, the TC MIB here: https://tools.ietf.org/html/rfc2579

Alan



-----Original Message-----
From: Martin T [mailto:***@gmail.com]
Sent: Friday, July 10, 2015 8:16 AM
To: net-snmp-***@lists.sourceforge.net
Subject: Are MIB files also used for converting SNMP GetResponse *values*?

Hi,

I am aware that MIB files in NMS are used to translate OID integers in SNMP GetResponse messages into meaningful names. For example here I can see that string "Vl290" is an VLAN-interface name:

$ snmpget -Of -v 2c -c public 10.10.10.1 .1.3.6.1.2.1.31.1.1.1.1.290
.iso.org.dod.internet.mgmt.mib-2.ifMIB.ifMIBObjects.ifXTable.ifXEntry.ifName.290
= STRING: Vl290
$


Without Cisco MIBs I would see:

$ snmpget -m /dev/null -Of -v 2c -c public 10.10.10.1
.1.3.6.1.2.1.31.1.1.1.1.290
.iso.3.6.1.2.1.31.1.1.1.1.290 = STRING: "Vl290"
$


However, are MIB files also used for converting SNMP GetResponse values? I mean for example "snmpwalk -Ov -v 2c -c public 10.10.10.1 sysUpTimeInstance" returns "Timeticks: (88920401) 10 days, 7:00:04.01", but this conversion is done in snmpget/snmpwalk utility itself. For example is it possible to define in MIB files that for example 1099 integer32 value in SNMP GetResponse message should be understood as 10cm and 99mm and then snmpget/snmpwalk utility will do such conversions automatically? I tried to find such SNMP objects, but did not find any.


thanks,
Martin

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[Martin T]

Alan,

thanks! So in short, looks like sometimes the returned values are
actually formatted based on MIB files. However, while I modified the
"InetAddressIPv4" or "InetAddressIPv6" terms in INET-ADDRESS-MIB.txt
MIB file or "PhysAddress" and "MacAddress" terms in SNMPv2-TC.txt
file, it had no affect to returned values. For example if I changed
the DISPLAY-HINT for "InetAddressIPv4" from "1d.1d.1d.1d" to
"1d:1d:1d:1d", then all the requests made for IPv4 addresses were
still formatted in "1d.1d.1d.1d" notation. On the other hand, the
DESCRIPTION for "InetAddressIPv4" term says that "This textual
convention SHOULD NOT be used directly in object definitions". So
correct me if I'm wrong, but while it is possible to define the format
of SNMP GetResponse values in MIB files, such conversions are in
practice usually not done in MIB files?


thanks,
Martin

Post by Robson, Alan
https://tools.ietf.org/html/rfc2579
Alan
-----Original Message-----
Sent: Friday, July 10, 2015 8:16 AM
Subject: Are MIB files also used for converting SNMP GetResponse *values*?
Hi,
I am aware that MIB files in NMS are used to translate OID integers in SNMP
GetResponse messages into meaningful names. For example here I can see that
$ snmpget -Of -v 2c -c public 10.10.10.1 .1.3.6.1.2.1.31.1.1.1.1.290
.iso.org.dod.internet.mgmt.mib-2.ifMIB.ifMIBObjects.ifXTable.ifXEntry.ifName.290
= STRING: Vl290
$
$ snmpget -m /dev/null -Of -v 2c -c public 10.10.10.1
.1.3.6.1.2.1.31.1.1.1.1.290
.iso.3.6.1.2.1.31.1.1.1.1.290 = STRING: "Vl290"
$
However, are MIB files also used for converting SNMP GetResponse values? I
mean for example "snmpwalk -Ov -v 2c -c public 10.10.10.1 sysUpTimeInstance"
returns "Timeticks: (88920401) 10 days, 7:00:04.01", but this conversion is
done in snmpget/snmpwalk utility itself. For example is it possible to
define in MIB files that for example 1099 integer32 value in SNMP
GetResponse message should be understood as 10cm and 99mm and then
snmpget/snmpwalk utility will do such conversions automatically? I tried to
find such SNMP objects, but did not find any.
thanks,
Martin
------------------------------------------------------------------------------
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GigeNET's Cloud Solutions provide you with the tools and support that you
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[Robson, Alan]

I had never thought to try that,

So to check my understanding...

1) You used something like snmpget to fetch an OID from the INET-ADDRESS-MIB that corresponded to an ipv4 address, and it displayed on the screen formatted as "a.b.c.d"
2) You modified the INET-ADDRESS-MIB.txt file to change the display hint to use colons instead of periods in ipv4 adddresses
3) You repeated the snmpget but the format of the string that it printed did not change.

That is ingenious. I suppose it would depend on when the snmpget program (in my example) read the MIB.txt files in question. I'd like to learn more. Could you please give an example. Are you using the command line snmpget tool ?

Many thanks

Alan

-----Original Message-----
From: Martin T [mailto:***@gmail.com]
Sent: Monday, July 13, 2015 6:54 AM
To: Robson, Alan
Cc: net-snmp-***@lists.sourceforge.net
Subject: Re: Are MIB files also used for converting SNMP GetResponse *values*?

Alan,

thanks! So in short, looks like sometimes the returned values are actually formatted based on MIB files. However, while I modified the "InetAddressIPv4" or "InetAddressIPv6" terms in INET-ADDRESS-MIB.txt MIB file or "PhysAddress" and "MacAddress" terms in SNMPv2-TC.txt file, it had no affect to returned values. For example if I changed the DISPLAY-HINT for "InetAddressIPv4" from "1d.1d.1d.1d" to "1d:1d:1d:1d", then all the requests made for IPv4 addresses were still formatted in "1d.1d.1d.1d" notation. On the other hand, the DESCRIPTION for "InetAddressIPv4" term says that "This textual convention SHOULD NOT be used directly in object definitions". So correct me if I'm wrong, but while it is possible to define the format of SNMP GetResponse values in MIB files, such conversions are in practice usually not done in MIB files?


thanks,
Martin

https://urldefense.proofpoint.com/v2/url?u=https-3A__tools.ietf.org_ht
ml_rfc2579&d=AwIFaQ&c=jcv3orpCsv7C4ly8-ubDob57ycZ4jvhoYZNDBA06fPk&r=xN
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7tWfMCMmhUNdC8Sw0&s=3rwzjvR_LkTT88HDzMesl6hwwwnB2d-oFGlt1w0HxwY&e=
Alan
-----Original Message-----
Sent: Friday, July 10, 2015 8:16 AM
Subject: Are MIB files also used for converting SNMP GetResponse *values*?
Hi,
I am aware that MIB files in NMS are used to translate OID integers in
SNMP GetResponse messages into meaningful names. For example here I
$ snmpget -Of -v 2c -c public 10.10.10.1 .1.3.6.1.2.1.31.1.1.1.1.290
.iso.org.dod.internet.mgmt.mib-2.ifMIB.ifMIBObjects.ifXTable.ifXEntry.
ifName.290
= STRING: Vl290
$
$ snmpget -m /dev/null -Of -v 2c -c public 10.10.10.1
.1.3.6.1.2.1.31.1.1.1.1.290
.iso.3.6.1.2.1.31.1.1.1.1.290 = STRING: "Vl290"
$
However, are MIB files also used for converting SNMP GetResponse
values? I mean for example "snmpwalk -Ov -v 2c -c public 10.10.10.1 sysUpTimeInstance"
returns "Timeticks: (88920401) 10 days, 7:00:04.01", but this
conversion is done in snmpget/snmpwalk utility itself. For example is
it possible to define in MIB files that for example 1099 integer32
value in SNMP GetResponse message should be understood as 10cm and
99mm and then snmpget/snmpwalk utility will do such conversions
automatically? I tried to find such SNMP objects, but did not find any.
thanks,
Martin
----------------------------------------------------------------------
-------- Don't Limit Your Business. Reach for the Cloud.
GigeNET's Cloud Solutions provide you with the tools and support that
you need to offload your IT needs and focus on growing your business.
Configured For All Businesses. Start Your Cloud Today.
https://urldefense.proofpoint.com/v2/url?u=https-3A__www.gigenetcloud.
com_&d=AwICAg&c=jcv3orpCsv7C4ly8-ubDob57ycZ4jvhoYZNDBA06fPk&r=xN9AnMDZ
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