February 2024
Beginner to intermediate
304 pages
9h 13m
Japanese
Content preview from 実務で使える メール技術の教科書 基本のしくみからプロトコル・サーバー構築・送信ドメイン認証・添付ファイル・暗号化・セキュリティ対策まで
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6
−
3
—
—
DNSSEC
■ DNS の応答にデジタル署名を付加する
第 1 章では、DNS が分散型で運営されており、フルサービスリゾルバーが
一定の期間はキャッシュを保持しておくことを解説しました。
これは効果的なしくみですが、悪意のあるサーバーが存在することを想定し
ていません。権威 DNS サーバーがフルサービスリゾルバーに応答する前に、
偽の権威 DNS サーバーが偽の応答を返すとどうなるでしょうか？【図 6-13】
図 6-13
偽の DNS サーバーによる応答
偽のDNS
サーバーが
先に勝手に
応答
偽の
DNSサーバー
⑦
⑧
⑥
⑤
④
③
②①
example.comのDNSサーバー
.comのDNSサーバー
DNS
ルートサーバー
フルサービスリゾルバー
・偽の応答を返す DNS サーバーを使った攻撃に対策したいとき
・送信側のメールサーバーに対するダウングレード攻撃を防ぎたいとき
・メール送信時の TLS の問題をメールや Web から報告したいとき
使えるのはこんな人や場面！
6
3
DNSSEC
257
250-266̲mail̲NSM̲F3.indd257250-266̲mail̲NSM̲F3.indd257 2024/01/309:572024/01/309:57
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.