The policy Limen.Plug uses when none is given.
A conservative starting point meant to be run in dry-run mode first: it
lets through clients in list(:allow) and crawlers verified by DNS,
challenges clearly automated traffic, denies only extreme scores, and never
bans. Copy it into your application to tune it.
Its rules are listed by Limen.Policy.describe/1:
iex> Limen.Policy.describe(Limen.Policy.Default) =~ "score +30 tool_user_agent"
true