Disable SNMP by default

[cotosso]

SNMP is enabled by default on the system, potentially exposing sensitive information such as interfaces, and IP addresses, which could be exploited in an attack.

Proposed Solution

Disable SNMP by default in the system configuration.
Provide an option to enable SNMP only if explicitly required by the user, ensuring it is not active in standard deployments.

[Tbaile]

Image: https://github.com/NethServer/nethsecurity/actions/runs/13460119085/artifacts/2631237583

QA:

• Update a 1.4.1, check that the service is still running snmpwalk -v 2c -c public 127.0.0.1
• Fresh install, the command snmpwalk -v 2c -c public 127.0.0.1 shouldn't return anything

NOTE: command must be ran inside the unit.

[cotosso]

1. Update a 1.4.1, check that the service is still running snmpwalk -v 2c -c public 127.0.0.1 : VERIFIED

2. Fresh install, the command snmpwalk -v 2c -c public 127.0.0.1 shouldn't return anything : VERIFIED