Billion M500 User Manual page 156

By default, the "Access Control" has two default rules.
Default Rule 1: (Index 0), a rule to allow only clients from LAN to have access to all embedded
applications (Web, FTP, etc). Under this situation, clients from WAN cannot access the router even
from Ping.
Default Rule 2: (Index 1), an ACL rule to open Ping to WAN side.
152