When I run any commands such as:
# snmptranslate .1.3.6.1.4.1.28318.1.1.3
SNMPv2-SMI::enterprises.28318.1.1.3
# snmpwalk 58.196.58.149 1.3.6.1.4.1.28318.1.1.3
SNMPv2-SMI::enterprises.28318.1.1.3.1.0 = STRING: "89-14-a8-52-a4-46"
SNMPv2-SMI::enterprises.28318.1.1.3.2.0 = STRING: "058.196.58.149/255.255.255.252"
SNMPv2-SMI::enterprises.28318.1.1.3.3.0 = STRING: "058.196.58.149"
SNMPv2-SMI::enterprises.28318.1.1.3.6.0 = STRING: "137.010.060.016"
SNMPv2-SMI::enterprises.28318.1.1.3.7.0 = STRING: "137.010.060.017"
SNMPv2-SMI::enterprises.28318.1.1.3.8.0 = INTEGER: 0
SNMPv2-SMI::enterprises.28318.1.1.3.9.0 = INTEGER: 0
SNMPv2-SMI::enterprises.28318.1.1.3.10.0 = STRING: "reserved"
I would like net-snmp to translate .1.3.6.1.4.1.28318.1.1.3 to the textual MIB formats. I'm not sure how to debug this.
I have this in my /etc/snmp/snmp.conf:
# cat /etc/snmp/snmp.conf
mibdirs /usr/share/snmp/mibs
defVersion 2c
defCommunity public
Where all my MIBs are in /usr/share/snmp/mibs. I know that 1.3.6.1.4.1.28318.1.1.3.0 corresponds to a textual MIB name of mac representing the mac address.
Any idea how to debug what has gone wrong and fix the problem?
The issue is that net-snmp doesn't load MIBs even if they're specified in the MIB directory.
So by adding mibs to the /etc/snmp/snmp.conf file fixed it:
# cat /etc/snmp/snmp.conf
mibdirs /usr/share/snmp/mibs
mibs +MYMIB
defVersion 2c
defCommunity public
The OID is translated properly. This can also be debugged by doing a:
$ snmptranslate -m +MYMIB -IR -On hello
MYMIB::hello = STRING: "WORLD"
Which will either output correctly above or show an issue. Note the -m +MYMIB doesn't have to be there if in the /etc/snmp/snmp.conf file.
Related
Consider the following main.c:
#include <stdio.h>
const char greeting[] = "hello world";
int main() {
printf("%s!\n", greeting);
return 0;
}
I compiled this in Ubuntu with:
gcc -g main.c -o main.exe
I would like to retrieve the value of the variable named greeting; considering it is const, it won't change, so it should be possible to retrieve the value "hello world" from the executable.
Basically, I can see the variable name in the binary using:
$ readelf -p .rodata main.exe | grep hello
[ 8] hello world
... and I can see the value using:
$ readelf -s main.exe | grep greeting
59: 0000000000002008 12 OBJECT GLOBAL DEFAULT 18 greeting
I could try parsing the output of readelf -s and readelf -p to get what I want (retrieve the value of the variable named greeting), but I'm pretty sure I'll mess it up.
So is there some combination of switches of bintools utilities (or any command line program, really), which would perform the equivalent of the following pseudocode:
$ [tool] --get-value-of-variable-name greeting --program=main.exe
"hello world"
or even:
$ [tool] --verbose --get-value-of-variable-name greeting --program=main.exe
The constant value of the variable "greeting" in `main.exe` is:
is there some combination of switches of bintools utilities (or any command line program, really), which would perform the equivalent of the following pseudocode:
Sure:
you need to find the section in which the symbol resides, and the address within that section, and the length of data, and
you need to find where in the file the section itself starts, and
you need to dump length bytes from the right offset in the file.
Getting this all together (my file has slightly different data from yours):
readelf -Ws main.exe | grep greeting
29: 0000000000002008 12 OBJECT GLOBAL DEFAULT 17 greeting
readelf -WS main.exe | grep '\[17\]'
[17] .rodata PROGBITS 0000000000002000 002000 000019 00 A 0 0 8
This tells me that I need to dump 12 bytes (actually 11, since I don't want the terminating \0), starting of offset 0x2000 + (0x2008 (symbol address) - 0x2000 (section address)).
dd if=main.exe bs=1 skip=$((0x2008)) count=11 2>/dev/null
hello world
Now, parsing this data out from readelf output is more trouble than it's worth -- it's much easier to write a simple C++ program to produce the desired output. Using ELFIO should make this very easy.
I am trying to set some OID but seems that it gives below error "No Such Instance currently exists at this OID" which should not be the case as i am able to get/walk same OID. so its present.
root#m-snm:~# snmpwalk -v 2c -c public 10.2.4.19 .1.3.6.1.2.1.2.2.1.7.3
iso.3.6.1.x.x.x.x.x.7.3 = INTEGER: 1
root#m-snm:~# snmpset -v 2c -c public 10.2.4.19 .1.3.6.1.2.1.2.2.1.7.3 i 2
iso.3.6.1.x.x.x.x.x.7.3 = **No Such Instance currently exists at this OID**
root#m-snm:~# snmpget -v 2c -c public 10.2.4.19 .1.3.6.1.2.1.2.2.1.7.3
iso.3.6.1.x.x.x.x.x.7.3 = INTEGER: 1
Is it the permission issue ? Or i am not allowed to write ? or the field itself is not writable ? how can check what field are r/w and what are readonly
I can ask to a snmp agent the query:
snmpwalk -v2c -c public 192.168.56.70 1.3.6.1.2.1.31.1.1.1.1.1
I recieve "lo" (loopback interface) as the answer. My question is: How I can access that OID through the names instead of using the OID numbers? That should be as follows:
snmpwalk -v2c -c public 192.168.56.70 iso.identified-organization.dod.internet.mgmt.mib-2.ifMIB.ifMIBObjects.ifXTable.ifXEntry.ifName
If I send this last query to the snmp agent, i get "Unknown Object Identification". Which changes should I do in the snmp agent configuration to get the same answer as when I am asking through the OID?
Any help will be appreciated, thanks!
Normally I'd use the simple symbolic name e.g.
snmptranslate -M+. -m +ALL 1.3.6.1.2.1.31.1.1.1.1.1
IF-MIB::ifName.1
From the agent's perspective the next two are the same, i.e. the netsnmp snmpwalk utility handles the symbol translations.
snmpwalk -v2c -c public 192.168.56.70 1.3.6.1.2.1.31.1.1.1.1.1
IF-MIB::ifName.1 = STRING: lo
Symbol version :
snmpwalk -v2c -c public 192.168.56.70 IF-MIB::ifName.1
IF-MIB::ifName.1 = STRING: lo
Include the MIB files if they're not in your default path -M+. -m +ALL
snmpwalk -v2c -c public vvx1 IF-MIB::ifName.1
IF-MIB::ifName.1 = STRING: lo
Which of the following is the correct format for snmptrap (net-snmp) command?
snmptrap -v 2c -c public host "" NET-SNMP-EXAMPLES-MIB::netSnmpExampleHeartbeatNotification \
netSnmpExampleHeartbeatRate i 123456
or
snmptrap -v 2c -c public host "" NET-SNMP-EXAMPLES-MIB::netSnmpExampleHeartbeatNotification \
netSnmpExampleHeartbeatRate.0 i 123456
i.e., with or without .0 in the variable bindings?
Actually both of these formats work, but which one is right or what is the difference?
It depends if "scalar" or a "table row"-related varbinds are being referred to in the trap.
http://www.net-snmp.org/wiki/index.php/TUT:snmptrap states :
Note that this command also includes an (OID,type,value) triple for
the varbinds listed in the VARIABLES clause (in the same way as with
the snmpset command).
Table row example.
snmptrap -v 2c -c public host:162 .1.3.6.1.6.3.1.1.5.3 .1.3.6.1.6.3.1.1.5.3 \
ifIndex i 2 ifAdminStatus i 1 ifOperStatus i 1
For reference :
snmptranslate -m +ALL -Pu .1.3.6.1.6.3.1.1.5.3
IF-MIB::linkDown
No .0 in the variable bindings since id is taken care of by the ifIndex which pinpoints the row.
Scalar row example.
http://www.net-snmp.org/wiki/index.php/TUT:snmptrap shows example
snmptrap -v 1 -c public host UCD-TRAP-TEST-MIB::demotraps "" 6 17 "" \
SNMPv2-MIB::sysLocation.0 s "Just here"
'SNMPv2-MIB::sysLocation.0' is a scalar.
Unlike IF-MIB::linkDown example above, which was related to a table row id-ed by the ifIndex, here the .0s at the end pinpoints the scalar (like when you SET it)
Netsnmp example from original question
mibs/NET-SNMP-EXAMPLES-MIB.txt states
netSnmpExampleHeartbeatRate OBJECT-TYPE
SYNTAX Integer32
MAX-ACCESS accessible-for-notify
STATUS current
DESCRIPTION
"A simple integer object, to act as a payload for the
netSnmpExampleHeartbeatNotification. The value has
no real meaning, but is nominally the interval (in
seconds) between successive heartbeat notifications."
::= { netSnmpExampleNotificationObjects 1 }
i.e. it is not a real, identifiable, accessible scalar so I recommend no .0.
I try to create a custom SNMP oid (and script).
I add the following line to snmpd.conf (and restart service) :
pass .1.3.6.1.3.2 /bin/myscript.sh
.
cat myscript.sh
#!/bin/sh
echo .1.3.6.1.3.2
echo gauge
exec 100
.
snmpwalk -c mycommunity -v2c 10.2.1.4 .1.3.6.1.3.2
SNMPv2-SMI::experimental.2 = Gauge32: 100
Error: OID not increasing: SNMPv2-SMI::experimental.2
>= SNMPv2-SMI::experimental.2
Is snmpwalk expecting anything at the end of the query ? snmpget work with no problem!
By default snmpwalk expect the value to be increasing. To get around it try:
snmpwalk -Cc -c mycommunity -v2c 10.2.1.4 .1.3.6.1.3.2
The Cc option does this:
"do not check returned OIDs are increasing"
Often the walk can be completed with oid:s out of order using this.
snmpwalk expects increasing replies :
SNMPv2-SMI::experimental.2 = Gauge32: 100
SNMPv2-SMI::experimental.3 = Gauge32: 1125
SNMPv2-SMI::other.1 = Gauge32: 10
END
It appears that the snmp agent replies two identical values :
SNMPv2-SMI::experimental.2 = Gauge32: 100
SNMPv2-SMI::experimental.2 = Gauge32: 100
So it fails (unexpected behaviour).