fix_snmp enabled os-net-snmp with community "public", contact
netork@localhost and location "Managed by netOrk", and added a
floating pass rule for UDP/161 from any source on every interface: a
firewall managed over WAN answered its SNMP tree to anyone there (#13).
The driver implements napalm-device-types 4.13's configure_snmp_agent
steps instead:
- install: os-net-snmp only when missing (a reinstall resets it);
- configure: community, contact, location and listen address from the
caller; a DNS name is not a listen address; a refused save fails;
- firewall: one floating pass rule per allowed source, the old
any-source rule and rules of an earlier run replaced, operators'
rules untouched; no sources, no change;
- start: restart net-snmp.
The hand-built UDP probe goes; the caller asks the agent itself.
BREAKING CHANGE: run_device_action is removed. Requires
napalm-device-types 4.13.
Closes#13
