Comment 6 for bug 1892980

Hi,

Thanks for following up.
Here are steps to reproduce it.

1. Login to an Ubuntu 18 server.
e.g.

docker run --name ubuntu18 -it ubuntu:bionic

2. apt-get update

3. apt-get install snmp snmp-mibs-downloader snmpd
(5.7.3+dfsg-1.8ubuntu3.5 will be installed)

4. Use the following config:

cat << EOF > /etc/snmp/snmpd.conf
com2sec private localhost test
group readwrite v1 private

view all included .1 80
access readonly "" any noauth exact all none none
access readwrite "" any noauth exact all all none

extend unixtime /bin/date +%s
EOF

5. service snmpd start

6. Run tests

The following command to set cache time to -1 will fail:
snmpset -v1 -c test localhost 'NET-SNMP-EXTEND-MIB::nsExtendCacheTime."unixtime"' i -1

We can also observe that nsExtendCacheTime is still 5 seconds.
snmpwalk -v1 -c test localhost "NET-SNMP-EXTEND-MIB::nsExtendCacheTime"

And the following result will be cached for 5 seconds.
snmpwalk -v1 -c test localhost 'NET-SNMP-EXTEND-MIB::nsExtendOutLine."unixtime"'

7. Test another versions

apt-get install libsnmp30=5.7.3+dfsg-1.8ubuntu3 \
snmp=5.7.3+dfsg-1.8ubuntu3 \
snmpd=5.7.3+dfsg-1.8ubuntu3

pkill snmpd

Then, repeat steps 5, 6, it will success to change cache time to -1 and the result is not cached anymore, which is our expected behavior.

Let me know if you have any problem to reproduce the issue.