Rate Limit about pttbbs

[wens]

It is possible to for the system to look at past login IPs to try to discern a pattern for each user, as they log on. By country sounds like a good idea. Going deeper you would need to define a proper "distance" for IPs, which is really hard to do. It might make sense to check if a user stays within clusters of IPs, but cellphones make this non-trivial.

Also, throttling by IPs hurts people behind NATs.

系統可以在使用者登入的時候，試圖分析使用者目前以及過去登入的 IP 看是不是有規律。依照國家是個不錯的方式。如果要更細微就必須先定義什麼叫做 IP 範圍很大，這其實不太容易。或許可以看使用者是不是固定從某些IP群登入，但是手機會讓這很難做。

此外，根據 IP 去限制流量、登入、或發文，其實對 NAT 後面的使用者相當不友善。