this tutorial video succeeds my howto on snmpd setup
in TLS/DTLS mode. There is the link:

In CentOS/RHEL 7 Linux we're going to setup SNMP v3 snmptrapd to accept secure TLS/DTLS informs and traps.
We will also modify snmpd to generate trapsess using TLS/DTLS.

List of used commands:
____________
1) Where are we?
cat /etc/centos-release

2) List installed net-snmp RPMs
rpm -qa | grep net-snmp

3) Show available TLS certificates
net-snmp-cert showcerts --fingerprint

4) On the manager, open /etc/snmp/snmptrapd.conf
vim /etc/snmp/snmptrapd.conf

5) Add there following lines. We will have to insert
real SHA1 fingerprints as retrieved in step 3
[snmp] localCert {manager certificate}
certSecName 20 {agent certificate} --sn trapuser
authUser log -s tsm trapuser

6) On the manager open /etc/sysconfig/snmptrapd
vim /etc/sysconfig/snmptrapd

7) Add there following lines. We have to enable
snmptrapd to listen
on TLS/DTLS ports. Replace hostnames with your real.
OPTIONS="-Lsd -p /var/run/snmptrapd.pid 127.0.0.1:162 {hostname}:162 dtlsudp:127.0.0.1:10162 tlstcp:127.0.0.1:10162 dtlsudp:{hostname}:10162 tlstcp:{hostname}:10162 -m ALL -M /opt/share/snmp/mibs:/usr/share/snmp/mibs"

8) On the manager enable snmptrapd and start it
systemctl enable snmptrapd
systemctl start snmptrapd

9) On the manager, monitor /var/log/messages for
new SNMP messages
tail -f /var/log/messages

10) On the agent generate inform message from
commandline. First to DTLS port
snmpinform -v 3 -u trapuser -T our_identity={agent certificate}
-T their_identity={manager certificate} dtlsudp:{hostname}:10162 42 coldStart.0

It works! Message appeared in the log on the manager node.

11) Now the same with TLS port.
snmpinform -v 3 -u trapuser -T our_identity={agent certificate}
-T their_identity={manager certificate} tlstcp:{hostname}:10162

Works again! Message arrived too.

12) Informs works.
Now the second part - trapsess - informs generated
by snmpd.

13) On the agent open the /etc/snmp/snmpd.conf
vim /etc/snmp/snmpd.conf

14) Add trapsess DTLS definition
trapsess -T our_identity={agent certificate} -T their_identity={manager certificate} dtlsudp:{hostname}:10162

16) Restart snmpd. Start/stop of snmpd generates trap as well. Watch /var/log/messages
systemctl restart snmpd

source by Jaroslav Kucera

simple network management protocol