fix_snmp wrote an application's snmpd.conf (community public, Managed by netOrk, netork@localhost) and judged itself by a local snmpget. The drivers implement napalm-device-types 4.13's SnmpAgentMixin steps instead: net-snmp installed, snmpd.conf with one rocommunity line per allowed source (staged without privilege, installed by root), snmpd enabled and restarted. pf and ipfw rules stay the operator's. A community or text that would break the file is refused. The caller verifies with its own SNMP client. Also get_management_peer() from SSH_CONNECTION, ensure_package from the base package, and get_snmp_config no longer assumes "public". BREAKING CHANGE: run_device_action is removed. Requires napalm-device-types 4.13. Closes #12