What are the OID's for Raspberry Pi CPU, memoria, interfaces?

Question

I am setting up MRTG on a Raspberry Pi 3+ B. When I try to run MRTG, it fails with this error:

pi@pi:/etc $ sudo mrtg
SNMP Error:
no response received
SNMPv1_Session (remote host: "pi" [127.0.1.1].161)
                  community: "public"
                 request ID: 2020852752
                PDU bufsize: 8000 bytes
                    timeout: 2s
                    retries: 5
                    backoff: 1)
 at /usr/share/perl5/SNMP_util.pm line 497.
SNMPGET Problem for .1.3.6.1.2.1.25.3.3.1.2.768 1.3.6.1.2.1.25.1.7.0 sysUptime sysName on public@pi::::::v4only
 at /usr/bin/mrtg line 2435.
2020-06-05 11:39:30: WARNING: skipping because at least the query for .1.3.6.1.2.1.25.3.3.1.2.768 on  pi did not succeed
2020-06-05 11:39:30: WARNING: no data for .1.3.6.1.2.1.25.3.3.1.2&1.3.6.1.2.1.25.1.7:public@pi. Skipping further queries for Host pi in this round.
2020-06-05 11:39:40: ERROR: Target[pi-cpu][_IN_] ' $target->[0]{$mode} ' did not eval into defined data
2020-06-05 11:39:40: ERROR: Target[pi-cpu][_OUT_] ' $target->[0]{$mode} ' did not eval into defined data

Question

I presume the OID is wrong. Where do I find the OIDs of the CPU, memory, network interfaces ...?

Environment

1) Raspbian GNU/Linux 10 (buster)

2) NET-SNMP version: 5.7.3

3) lighttpd/1.4.53 (ssl) - a light and fast webserver

4) /etc/mrtg.conf

WorkDir: /var/www/html/mrtg
WriteExpires: Yes
Title[^]: Traffic Analysis for
WorkDir: /var/www/html/mrtg

EnableIPv6: no
Target[pi-CPU]: .1.3.6.1.2.1.25.3.3.1.2.768&1.3.6.1.2.1.25.1.7.0:public@pi
MaxBytes[pi-CPU]: 100
YLegend[pi-CPU]: CPU %
ShortLegend[pi-CPU]: %
LegendI[pi-CPU]: CPU
Legend1[pi-CPU]: CPU usage
Options[pi-CPU]: integer, gauge, nopercent, growright, unknaszero, noo
Title[pi-CPU]: Raspberry Pi 3 CPU load
PageTop[pi-CPU]: <H1>Raspberry Pi 3 - CPU load</H1>

Tests

Checking out the OID .1.3.6.1.2.1.25.3.3.1.2.768

pi@pi:/etc $ snmpget -v 1 -c public localhost .1.3.6.1.2.1.25.3.3.1.2.768
Error in packet
Reason: (noSuchName) There is no such variable name in this MIB.
Failed object: iso.3.6.1.2.1.25.3.3.1.2.768

Checking snmpwalk:

pi@pi:~ $ snmpwalk  -c public -v 1 localhost .1.3
iso.3.6.1.2.1.1.1.0 = STRING: "Linux pi 4.19.118-v7+ #1311 SMP Mon Apr 27 14:21:24 BST 2020 armv7l"
iso.3.6.1.2.1.1.2.0 = OID: iso.3.6.1.4.1.8072.3.2.10
iso.3.6.1.2.1.1.3.0 = Timeticks: (1153304) 3:12:13.04
iso.3.6.1.2.1.1.4.0 = STRING: "Me <me@example.org>"
iso.3.6.1.2.1.1.5.0 = STRING: "pi"
iso.3.6.1.2.1.1.6.0 = STRING: "Sitting on the Dock of the Bay"
iso.3.6.1.2.1.1.7.0 = INTEGER: 72
iso.3.6.1.2.1.1.8.0 = Timeticks: (25) 0:00:00.25
iso.3.6.1.2.1.1.9.1.2.1 = OID: iso.3.6.1.6.3.11.3.1.1
iso.3.6.1.2.1.1.9.1.2.2 = OID: iso.3.6.1.6.3.15.2.1.1
iso.3.6.1.2.1.1.9.1.2.3 = OID: iso.3.6.1.6.3.10.3.1.1
iso.3.6.1.2.1.1.9.1.2.4 = OID: iso.3.6.1.6.3.1
iso.3.6.1.2.1.1.9.1.2.5 = OID: iso.3.6.1.6.3.16.2.2.1
iso.3.6.1.2.1.1.9.1.2.6 = OID: iso.3.6.1.2.1.49
iso.3.6.1.2.1.1.9.1.2.7 = OID: iso.3.6.1.2.1.4
iso.3.6.1.2.1.1.9.1.2.8 = OID: iso.3.6.1.2.1.50
iso.3.6.1.2.1.1.9.1.2.9 = OID: iso.3.6.1.6.3.13.3.1.3
iso.3.6.1.2.1.1.9.1.2.10 = OID: iso.3.6.1.2.1.92
iso.3.6.1.2.1.1.9.1.3.1 = STRING: "The MIB for Message Processing and Dispatching."
iso.3.6.1.2.1.1.9.1.3.2 = STRING: "The management information definitions for the SNMP User-based Security Model."
iso.3.6.1.2.1.1.9.1.3.3 = STRING: "The SNMP Management Architecture MIB."
iso.3.6.1.2.1.1.9.1.3.4 = STRING: "The MIB module for SNMPv2 entities"
iso.3.6.1.2.1.1.9.1.3.5 = STRING: "View-based Access Control Model for SNMP."
iso.3.6.1.2.1.1.9.1.3.6 = STRING: "The MIB module for managing TCP implementations"
iso.3.6.1.2.1.1.9.1.3.7 = STRING: "The MIB module for managing IP and ICMP implementations"
iso.3.6.1.2.1.1.9.1.3.8 = STRING: "The MIB module for managing UDP implementations"
iso.3.6.1.2.1.1.9.1.3.9 = STRING: "The MIB modules for managing SNMP Notification, plus filtering."
iso.3.6.1.2.1.1.9.1.3.10 = STRING: "The MIB module for logging SNMP Notifications."
iso.3.6.1.2.1.1.9.1.4.1 = Timeticks: (14) 0:00:00.14
iso.3.6.1.2.1.1.9.1.4.2 = Timeticks: (14) 0:00:00.14
iso.3.6.1.2.1.1.9.1.4.3 = Timeticks: (14) 0:00:00.14
iso.3.6.1.2.1.1.9.1.4.4 = Timeticks: (14) 0:00:00.14
iso.3.6.1.2.1.1.9.1.4.5 = Timeticks: (14) 0:00:00.14
iso.3.6.1.2.1.1.9.1.4.6 = Timeticks: (15) 0:00:00.15
iso.3.6.1.2.1.1.9.1.4.7 = Timeticks: (15) 0:00:00.15
iso.3.6.1.2.1.1.9.1.4.8 = Timeticks: (15) 0:00:00.15
iso.3.6.1.2.1.1.9.1.4.9 = Timeticks: (25) 0:00:00.25
iso.3.6.1.2.1.1.9.1.4.10 = Timeticks: (25) 0:00:00.25
iso.3.6.1.2.1.25.1.1.0 = Timeticks: (1155270) 3:12:32.70
iso.3.6.1.2.1.25.1.2.0 = Hex-STRING: 07 E4 06 05 0B 38 32 00 2D 04 00 
iso.3.6.1.2.1.25.1.3.0 = INTEGER: 393216
iso.3.6.1.2.1.25.1.4.0 = STRING: "coherent_pool=1M 8250.nr_uarts=0 snd_bcm2835.enable_compat_alsa=0 snd_bcm2835.enable_hdmi=1 snd_bcm2835.enable_headphones=1 bcm2"
iso.3.6.1.2.1.25.1.5.0 = Gauge32: 4
iso.3.6.1.2.1.25.1.6.0 = Gauge32: 157
iso.3.6.1.2.1.25.1.7.0 = INTEGER: 0
End of MIB

Checking out an OID extracted from snmpwalk:

pi@pi:~ $ snmpget -v 1 -c public localhost iso.3.6.1.2.1.1.9.1.4.1
iso.3.6.1.2.1.1.9.1.4.1 = Timeticks: (14) 0:00:00.14

Checking the web page:

Answer 1

My bad. I omitted this single step while configuring snmpd:

Once that installs, the /etc/snmp/snmpd.conf needs to be edited. Open that file in your text editor of choice and change the line:

#rocommunity public localhost

to

rocommunity public localhost

After correcting the error, I run again

sudo cfgmaker public@localhost > /etc/mrtg.cfg
sudo indexmaker /etc/mrtg.cfg > /var/www/html/mrtg/index.html
sudo mrtg

[I'm using lighttpd instead of apache. Hence the path /var/www/html/mrtg]

And voila, everything works!