DNS Security

微討論 + DNSSEC 簡介

複習一下 DNS

https://www.cloudflare.com/learning/dns/what-is-dns/

user

nameserver(s)

resolver

1.1.1.1

8.8.8.8

DNS zone

https://www.cloudflare.com/learning/dns/glossary/dns-zone/

DNS 訊息

;; QUESTION SECTION:
;google.com.			IN	A

;; ANSWER SECTION:
google.com.		300	IN	A	216.58.200.238

有答案：

去問別人：

;; QUESTION SECTION:
;google.com.			IN	A

;; AUTHORITY SECTION:
com.			172800	IN	NS	l.gtld-servers.net.
com.			172800	IN	NS	b.gtld-servers.net.
com.			172800	IN	NS	c.gtld-servers.net.


;; ADDITIONAL SECTION:
l.gtld-servers.net.	172800	IN	A	192.41.162.30
b.gtld-servers.net.	172800	IN	A	192.33.14.30
c.gtld-servers.net.	172800	IN	A	192.26.92.30

type

resource record (RR)

type

resource record (RR)

resource record (RR)

resource record (RR)

DNS 訊息內容

// response from root zone ==============================================================================================================
;; QUESTION SECTION:
;community.cloudflare.com.	IN	A

;; AUTHORITY SECTION:
com.			172800	IN	NS	a.gtld-servers.net.
com.			172800	IN	NS	b.gtld-servers.net.
com.			172800	IN	NS	c.gtld-servers.net.
com.			172800	IN	NS	d.gtld-servers.net.
com.			172800	IN	NS	e.gtld-servers.net.
com.			172800	IN	NS	f.gtld-servers.net.
com.			172800	IN	NS	g.gtld-servers.net.
com.			172800	IN	NS	h.gtld-servers.net.
com.			172800	IN	NS	i.gtld-servers.net.
com.			172800	IN	NS	j.gtld-servers.net.
com.			172800	IN	NS	k.gtld-servers.net.
com.			172800	IN	NS	l.gtld-servers.net.
com.			172800	IN	NS	m.gtld-servers.net.
com.			86400	IN	DS	30909 8 2 E2D3C916F6DEEAC73294E8268FB5885044A833FC5459588F4A9184CF C41A5766
com.			86400	IN	RRSIG	DS 8 1 86400 20210427170000 20210414160000 14631 . jwahsbkHuNHBLp9YgL9d4EVhLmtgBaTHHyKZAla3//yfTJZSdjzasjlr jQztqmJE/eESu812+7DG7S1LFfs8TMoyENlaxUoBuqB5PVAec2B2aiW2 udE8MSPUJ55VaOEAPIg8WWj5U81b8L28xWrnpCKTuP+nyKrOihGHHc5j FIByd9537+uUzwsCjKgQCEjllYb5n/jLvbHypqywkDwvboL5jV/Amo8h kmGBcm3BwKVoa44l56mHdwU29g2mUwErbzE5ac6SHcsWchQy2JSzSu7F cFXUDXRBJd1PPTiiKZZHJR/XhOMIy19Y5zsUsTcqpgKrIvTQBvbf1+Mt ZLq8Gw==

;; ADDITIONAL SECTION:
a.gtld-servers.net.	172800	IN	A	192.5.6.30
b.gtld-servers.net.	172800	IN	A	192.33.14.30
c.gtld-servers.net.	172800	IN	A	192.26.92.30
d.gtld-servers.net.	172800	IN	A	192.31.80.30
e.gtld-servers.net.	172800	IN	A	192.12.94.30
f.gtld-servers.net.	172800	IN	A	192.35.51.30
g.gtld-servers.net.	172800	IN	A	192.42.93.30
h.gtld-servers.net.	172800	IN	A	192.54.112.30
i.gtld-servers.net.	172800	IN	A	192.43.172.30
j.gtld-servers.net.	172800	IN	A	192.48.79.30
k.gtld-servers.net.	172800	IN	A	192.52.178.30
l.gtld-servers.net.	172800	IN	A	192.41.162.30
m.gtld-servers.net.	172800	IN	A	192.55.83.30
// ==============================================================================================================


// response from .com zone ==============================================================================================================
;; QUESTION SECTION:
;community.cloudflare.com.	IN	A

;; AUTHORITY SECTION:
cloudflare.com.		172800	IN	NS	ns3.cloudflare.com.
cloudflare.com.		172800	IN	NS	ns5.cloudflare.com.
cloudflare.com.		172800	IN	NS	ns4.cloudflare.com.
cloudflare.com.		172800	IN	NS	ns6.cloudflare.com.
cloudflare.com.		172800	IN	NS	ns7.cloudflare.com.
cloudflare.com.		86400	IN	DS	2371 13 2 32996839A6D808AFE3EB4A795A0E6A7A39A76FC52FF228B22B76F6D6 3826F2B9
cloudflare.com.		86400	IN	RRSIG	DS 8 2 86400 20210421041721 20210414030721 58540 com. AbNlrffLewRXntWb0GEkNsUSRWisQV8lVagZuD+RUpcsTjFPd/fkQInM XKfp6nSMB632tfceGPE3C1mr4jxR4lyV93O+MexAe1bEmSS5s1ZhX3Sb JWXkh/cZlS6yCDGBmlJHbgfwmVQ0vIvitfOw4VlxcAV+FYsRdF3C/ClT Dr8KQ1QY0kKHdp8TeLbVSkSmdm2wYBhi3kIcoomdsFkZHQ==

;; ADDITIONAL SECTION:
ns3.cloudflare.com.	172800	IN	A	162.159.0.33
ns3.cloudflare.com.	172800	IN	A	162.159.7.226
ns5.cloudflare.com.	172800	IN	A	162.159.2.9
ns5.cloudflare.com.	172800	IN	A	162.159.9.55
ns4.cloudflare.com.	172800	IN	A	162.159.1.33
ns4.cloudflare.com.	172800	IN	A	162.159.8.55
ns6.cloudflare.com.	172800	IN	A	162.159.3.11
ns6.cloudflare.com.	172800	IN	A	162.159.5.6
ns7.cloudflare.com.	172800	IN	A	162.159.4.8
ns7.cloudflare.com.	172800	IN	A	162.159.6.6
// ==============================================================================================================


// response from cloudflare.com zone ==============================================================================================================
;; QUESTION SECTION:
;community.cloudflare.com.	IN	A

;; ANSWER SECTION:
community.cloudflare.com. 300	IN	A	104.16.133.229
community.cloudflare.com. 300	IN	A	104.16.132.229
community.cloudflare.com. 300	IN	RRSIG	A 13 3 300 20210416013846 20210413233846 34505 cloudflare.com. JMiz99Buhxb6QbD51D/ysTzsG2Rz5ifr3lRo48PkOqLjt1Az37whx8AO NmA4kZAED5hJh3dZfZbNcoTtIdMnwg==
// ==============================================================================================================

DNS 的發展很早

明文傳輸 & 沒有簽章

1987 年

RFC 1034

RFC 1035

明文傳輸

隱私

隱含的安全性問題

看得到問了哪些 domain

沒有簽章

沒有簽章的話，沒辦法確定傳訊息的對象是誰

複習一下典型的數位簽章

用公鑰解密 → 解得開、內容沒錯 → 嗯是由對應的私鑰加密的

可以確保 1. 訊息沒有漏或被竄改 2. 訊息是有私鑰的人發的 

有私鑰的人

有可能不是我們以為的那個人

可能一開始公鑰就錯了

公鑰要有人背書

要有別人對這個公鑰做簽章

別人可能也不能相信

要有別人對別人的公鑰做簽章

這樣下去沒完沒了

要找到一個可以相信的人

他簽的公鑰我們都相信

他簽的公鑰簽的公鑰我們也相信

他簽的公鑰簽的公鑰簽的公鑰我們也相信

...

這就是信任鏈

DNS spoofing/cache poisoning

https://www.cloudflare.com/learning/dns/dns-cache-poisoning/

port number?

以前很多用固定的同一個

現在每個 request 隨機

request ID number?

以前可能數字遞增

現在也要亂

resolver

nameserver

DNS spoofing/cache poisoning

https://www.cloudflare.com/learning/dns/dns-cache-poisoning/

理論上 user 跟 resolver 之間的溝通也不安全

https://www.cloudflare.com/learning/dns/what-is-dns/

中國的防火長城

防火長城 wiki

有用 dns spoofing

Great Firewall wiki

DNSSEC (DNS Security Extensions)

有一堆 RFC，大約在 2000 年左右開始發布

是 DNS 的擴充

可以解決 resolver 跟 nameserver 間的信任問題

(雖然現在大多數網站還是沒有使用)

https://www.cloudflare.com/learning/dns/what-is-dns/

nameserver 除了回傳紀錄之外

同時回傳紀錄的簽章

key 由 parent zone 背書

RRSIG record 就是簽章

// response from root zone ==============================================================================================================
;; QUESTION SECTION:
;community.cloudflare.com.	IN	A

;; AUTHORITY SECTION:
com.			172800	IN	NS	a.gtld-servers.net.
com.			172800	IN	NS	b.gtld-servers.net.
com.			172800	IN	NS	c.gtld-servers.net.
com.			172800	IN	NS	d.gtld-servers.net.
com.			172800	IN	NS	e.gtld-servers.net.
com.			172800	IN	NS	f.gtld-servers.net.
com.			172800	IN	NS	g.gtld-servers.net.
com.			172800	IN	NS	h.gtld-servers.net.
com.			172800	IN	NS	i.gtld-servers.net.
com.			172800	IN	NS	j.gtld-servers.net.
com.			172800	IN	NS	k.gtld-servers.net.
com.			172800	IN	NS	l.gtld-servers.net.
com.			172800	IN	NS	m.gtld-servers.net.
com.			86400	IN	DS	30909 8 2 E2D3C916F6DEEAC73294E8268FB5885044A833FC5459588F4A9184CF C41A5766
com.			86400	IN	RRSIG	DS 8 1 86400 20210427170000 20210414160000 14631 . jwahsbkHuNHBLp9YgL9d4EVhLmtgBaTHHyKZAla3//yfTJZSdjzasjlr jQztqmJE/eESu812+7DG7S1LFfs8TMoyENlaxUoBuqB5PVAec2B2aiW2 udE8MSPUJ55VaOEAPIg8WWj5U81b8L28xWrnpCKTuP+nyKrOihGHHc5j FIByd9537+uUzwsCjKgQCEjllYb5n/jLvbHypqywkDwvboL5jV/Amo8h kmGBcm3BwKVoa44l56mHdwU29g2mUwErbzE5ac6SHcsWchQy2JSzSu7F cFXUDXRBJd1PPTiiKZZHJR/XhOMIy19Y5zsUsTcqpgKrIvTQBvbf1+Mt ZLq8Gw==

;; ADDITIONAL SECTION:
a.gtld-servers.net.	172800	IN	A	192.5.6.30
b.gtld-servers.net.	172800	IN	A	192.33.14.30
c.gtld-servers.net.	172800	IN	A	192.26.92.30
d.gtld-servers.net.	172800	IN	A	192.31.80.30
e.gtld-servers.net.	172800	IN	A	192.12.94.30
f.gtld-servers.net.	172800	IN	A	192.35.51.30
g.gtld-servers.net.	172800	IN	A	192.42.93.30
h.gtld-servers.net.	172800	IN	A	192.54.112.30
i.gtld-servers.net.	172800	IN	A	192.43.172.30
j.gtld-servers.net.	172800	IN	A	192.48.79.30
k.gtld-servers.net.	172800	IN	A	192.52.178.30
l.gtld-servers.net.	172800	IN	A	192.41.162.30
m.gtld-servers.net.	172800	IN	A	192.55.83.30
// ==============================================================================================================

// response from .com zone ==============================================================================================================
;; QUESTION SECTION:
;community.cloudflare.com.	IN	A

;; AUTHORITY SECTION:
cloudflare.com.		172800	IN	NS	ns3.cloudflare.com.
cloudflare.com.		172800	IN	NS	ns5.cloudflare.com.
cloudflare.com.		172800	IN	NS	ns4.cloudflare.com.
cloudflare.com.		172800	IN	NS	ns6.cloudflare.com.
cloudflare.com.		172800	IN	NS	ns7.cloudflare.com.
cloudflare.com.		86400	IN	DS	2371 13 2 32996839A6D808AFE3EB4A795A0E6A7A39A76FC52FF228B22B76F6D6 3826F2B9
cloudflare.com.		86400	IN	RRSIG	DS 8 2 86400 20210421041721 20210414030721 58540 com. AbNlrffLewRXntWb0GEkNsUSRWisQV8lVagZuD+RUpcsTjFPd/fkQInM XKfp6nSMB632tfceGPE3C1mr4jxR4lyV93O+MexAe1bEmSS5s1ZhX3Sb JWXkh/cZlS6yCDGBmlJHbgfwmVQ0vIvitfOw4VlxcAV+FYsRdF3C/ClT Dr8KQ1QY0kKHdp8TeLbVSkSmdm2wYBhi3kIcoomdsFkZHQ==

;; ADDITIONAL SECTION:
ns3.cloudflare.com.	172800	IN	A	162.159.0.33
ns3.cloudflare.com.	172800	IN	A	162.159.7.226
ns5.cloudflare.com.	172800	IN	A	162.159.2.9
ns5.cloudflare.com.	172800	IN	A	162.159.9.55
ns4.cloudflare.com.	172800	IN	A	162.159.1.33
ns4.cloudflare.com.	172800	IN	A	162.159.8.55
ns6.cloudflare.com.	172800	IN	A	162.159.3.11
ns6.cloudflare.com.	172800	IN	A	162.159.5.6
ns7.cloudflare.com.	172800	IN	A	162.159.4.8
ns7.cloudflare.com.	172800	IN	A	162.159.6.6
// ==============================================================================================================

// response from cloudflare.com zone ==============================================================================================================
;; QUESTION SECTION:
;community.cloudflare.com.	IN	A

;; ANSWER SECTION:
community.cloudflare.com. 300	IN	A	104.16.133.229
community.cloudflare.com. 300	IN	A	104.16.132.229
community.cloudflare.com. 300	IN	RRSIG	A 13 3 300 20210416013846 20210413233846 34505 cloudflare.com. JMiz99Buhxb6QbD51D/ysTzsG2Rz5ifr3lRo48PkOqLjt1Az37whx8AO NmA4kZAED5hJh3dZfZbNcoTtIdMnwg==
// ==============================================================================================================

RRSIG 也是一筆紀錄 (RR)

DNSSEC 新增了一些 RR 的 type

先看最後面 cloudflare.com 的 response

// response from cloudflare.com zone ==============================================================================================================
;; QUESTION SECTION:
;community.cloudflare.com.	IN	A

;; ANSWER SECTION:
community.cloudflare.com. 300	IN	A	104.16.133.229
community.cloudflare.com. 300	IN	A	104.16.132.229
community.cloudflare.com. 300	IN	RRSIG	A 13 3 300 20210416013846 20210413233846 34505 cloudflare.com. JMiz99Buhxb6QbD51D/ysTzsG2Rz5ifr3lRo48PkOqLjt1Az37whx8AO NmA4kZAED5hJh3dZfZbNcoTtIdMnwg==
// ==============================================================================================================

有兩個 key

而且也有 RRSIG

要驗證這個 RRSIG

會需要另一個 request 去拿 key

// response from cloudflare.com zone ==============================================================================================================
;; QUESTION SECTION:
;cloudflare.com.			IN	DNSKEY

;; ANSWER SECTION:
cloudflare.com.		3600	IN	DNSKEY	257 3 13 mdsswUyr3DPW132mOi8V9xESWE8jTo0dxCjjnopKl+GqJxpVXckHAeF+ KkxLbxILfDLUT0rAK9iUzy1L53eKGQ== (key id: 2371)
cloudflare.com.		3600	IN	DNSKEY	256 3 13 oJMRESz5E4gYzS/q6XDrvU1qMPYIjCWzJaOau8XNEZeqCYKD5ar0IRd8 KqXXFJkqmVfRvMGPmM1x8fGAa2XhSA== (key id: 34505)
cloudflare.com.		3600	IN	RRSIG	DNSKEY 13 2 3600 20210514040914 20210315040914 2371 cloudflare.com. jj+c/7Y67inA4heXnNUKBNOGI+B8Foy3wtcsgK0wXgX0ZlRhsyvc6Eys oJowpHvrz2/PCXDZD/z0yZ6eXEFADg==
// ==============================================================================================================

上面兩筆 A record 的簽章

上面兩筆 DNSKEY record 的簽章

兩個 key

// response from cloudflare.com zone ==============================================================================================================
;; QUESTION SECTION:
;cloudflare.com.			IN	DNSKEY

;; ANSWER SECTION:
cloudflare.com.		3600	IN	DNSKEY	257 3 13 mdsswUyr3DPW132mOi8V9xESWE8jTo0dxCjjnopKl+GqJxpVXckHAeF+ KkxLbxILfDLUT0rAK9iUzy1L53eKGQ== (key id: 2371)
cloudflare.com.		3600	IN	DNSKEY	256 3 13 oJMRESz5E4gYzS/q6XDrvU1qMPYIjCWzJaOau8XNEZeqCYKD5ar0IRd8 KqXXFJkqmVfRvMGPmM1x8fGAa2XhSA== (key id: 34505)
cloudflare.com.		3600	IN	RRSIG	DNSKEY 13 2 3600 20210514040914 20210315040914 2371 cloudflare.com. jj+c/7Y67inA4heXnNUKBNOGI+B8Foy3wtcsgK0wXgX0ZlRhsyvc6Eys oJowpHvrz2/PCXDZD/z0yZ6eXEFADg==
// ==============================================================================================================

257 是 key-signing key

256 是 zone-signing key

key-signing key 用來驗證 DNSKEY 的 RRSIG

zone-signing key 用來驗證其它 RRSIG

稍微整理一下

key-signing key 拿來驗證 DNSKEY record 的 RRSIG

zone-signing key 拿來驗證其它的 RRSIG

現在有兩個 RRSIG record

A record 有 RRSIG

DNSKEY record 也有 RRSIG

兩個 DNSKEY record

  • key-signing key
  • zone-signing key

所以

  • A record 由 zone-signing key 背書
  • zone-signing key 由 key-signing key 背書

要怎麼相信 key-signing key?

parent zone 給的 DS record

是 child zone 的 key-signing key 的 hash 值

// response from .com zone ==============================================================================================================
;; QUESTION SECTION:
;community.cloudflare.com.	IN	A

;; AUTHORITY SECTION:
cloudflare.com.		172800	IN	NS	ns3.cloudflare.com.
cloudflare.com.		172800	IN	NS	ns5.cloudflare.com.
cloudflare.com.		172800	IN	NS	ns4.cloudflare.com.
cloudflare.com.		172800	IN	NS	ns6.cloudflare.com.
cloudflare.com.		172800	IN	NS	ns7.cloudflare.com.
cloudflare.com.		86400	IN	DS	2371 13 2 32996839A6D808AFE3EB4A795A0E6A7A39A76FC52FF228B22B76F6D6 3826F2B9
cloudflare.com.		86400	IN	RRSIG	DS 8 2 86400 20210421041721 20210414030721 58540 com. AbNlrffLewRXntWb0GEkNsUSRWisQV8lVagZuD+RUpcsTjFPd/fkQInM XKfp6nSMB632tfceGPE3C1mr4jxR4lyV93O+MexAe1bEmSS5s1ZhX3Sb JWXkh/cZlS6yCDGBmlJHbgfwmVQ0vIvitfOw4VlxcAV+FYsRdF3C/ClT Dr8KQ1QY0kKHdp8TeLbVSkSmdm2wYBhi3kIcoomdsFkZHQ==

;; ADDITIONAL SECTION:
ns3.cloudflare.com.	172800	IN	A	162.159.0.33
ns3.cloudflare.com.	172800	IN	A	162.159.7.226
ns5.cloudflare.com.	172800	IN	A	162.159.2.9
ns5.cloudflare.com.	172800	IN	A	162.159.9.55
ns4.cloudflare.com.	172800	IN	A	162.159.1.33
ns4.cloudflare.com.	172800	IN	A	162.159.8.55
ns6.cloudflare.com.	172800	IN	A	162.159.3.11
ns6.cloudflare.com.	172800	IN	A	162.159.5.6
ns7.cloudflare.com.	172800	IN	A	162.159.4.8
ns7.cloudflare.com.	172800	IN	A	162.159.6.6


// response from cloudflare.com zone ==============================================================================================================
;; QUESTION SECTION:
;community.cloudflare.com.	IN	A

;; ANSWER SECTION:
community.cloudflare.com. 300	IN	A	104.16.133.229
community.cloudflare.com. 300	IN	A	104.16.132.229
community.cloudflare.com. 300	IN	RRSIG	A 13 3 300 20210416013846 20210413233846 34505 cloudflare.com. JMiz99Buhxb6QbD51D/ysTzsG2Rz5ifr3lRo48PkOqLjt1Az37whx8AO NmA4kZAED5hJh3dZfZbNcoTtIdMnwg==

再整理一下

  • A record 由 child zone 的 zone-signing key 背書
  • child zone 的 zone-signing key 由 key-signing key 背書
  • child zone 的 key-signing key 由 parent zone 的 DS record 背書
  • parent zone 的 DS record 由 parent zone 的 zone-signing key 背書
  • parent zone 的 zone-signing key 由 parent zone 的 key-signing key 背書
  • parent zone 的 key-signing key 由 parent zone 的 parent zone 的 DS record 背書
  • ...

從 root nameserver 開始的話

resolver 要預設定 root key-signing key 的 DS record

→ 可以相信 root zone 的 key-signing key

→ 可以相信 root zone 的 DNSKEY record (zone-signing key)

→ 可以相信 root zone 的 DS record (跟 NS record)

→ 可以相信 .com 的 key-signing key

→ 可以相信 .com 的 DNSKEY record (zone-signing key)

→ 可以相信 .com 的 DS record (跟 NS record)

→ 可以相信 cloudflare.com 的 key-signing key

→ 可以相信 cloudflare.com 的 DNSKEY record (zone-signing key)

→ 可以相信 cloudflare.com 的 A record

如果沒資料的話 要簽什麼

NSEC 或 NSEC3 Record

// response from cloudflare.com zone
;; QUESTION SECTION:
;ttjsioj90jkljfsgr.cloudflare.com. IN	A

;; AUTHORITY SECTION:
cloudflare.com.				300	IN	SOA	ns3.cloudflare.com. dns.cloudflare.com. 2037003995 10000 2400 604800 300
ttjsioj90jkljfsgr.cloudflare.com. 	300 	IN 	NSEC	\000.ttjsioj90jkljfsgr.cloudflare.com. RRSIG NSEC
cloudflare.com.				300	IN	RRSIG	SOA 13 2 300 20210416052852 20210414032852 34505 cloudflare.com. Em2EYGHAQI69NYZYQtO2A/Th6C8FTLEKu6VfWrvXNNHufkazWfjZw7JO 9ALBZAK3Y7+sFNXoL4xhh7hVB40KaA==
ttjsioj90jkljfsgr.cloudflare.com. 	300 	IN 	RRSIG	NSEC 13 3 300 20210416052852 20210414032852 34505 cloudflare.com. xXA4glHt7T38O5JNT12oe9EHy3BhHuxLabzHqSSNpD4XMY9iU0fr4iLs k/kkfl4+idUGqXTu1T7ShLsY1mUS+A==


// response from cloudflare.com zone
;; QUESTION SECTION:
;google.com.			IN	A

;; AUTHORITY SECTION:
google.com.		172800	IN	NS	ns2.google.com.
google.com.		172800	IN	NS	ns1.google.com.
google.com.		172800	IN	NS	ns3.google.com.
google.com.		172800	IN	NS	ns4.google.com.
CK0POJMG874LJREF7EFN8430QVIT8BSM.com. 86400 IN NSEC3 1 1 0 - CK0Q1GIN43N1ARRC9OSM6QPQR81H5M9A  NS SOA RRSIG DNSKEY NSEC3PARAM
CK0POJMG874LJREF7EFN8430QVIT8BSM.com. 86400 IN RRSIG NSEC3 8 2 86400 20210422042410 20210415031410 58540 com. fePohSpUOL9K9eCljlIgjwl8TiSbS1ahDo0B1FI9aIIZA3u1AuzKQgzK yRxC56l4SXq5oLvuUe8Xti4/G8ARewoTTNtgNN0KWIj7PKCNdLDSQYtu nF3HoZZLtoKomKgq6YXbdwt9+6Qern+as2SAI2pWvPPjsGVx0400tCNY C1YgPGOuMomEm/Fg/aWwW6uv/a+k7SJPSKIvJ0CLHiCmuw==
S84BDVKNH5AGDSI7F5J0O3NPRHU0G7JQ.com. 86400 IN NSEC3 1 1 0 - S84BUO64GQCVN69RJFUO6LVC7FSLUNJ5  NS DS RRSIG
S84BDVKNH5AGDSI7F5J0O3NPRHU0G7JQ.com. 86400 IN RRSIG NSEC3 8 2 86400 20210419042155 20210412031155 58540 com. q4Vpx7gnbxsb3HXnw9FCe203ZHl6pBDgAgVDQK3lA9eFh1XCGUbjcpwQ gjZbb7OfuSBa2Bee9J/YRMpUw11D5uXSllNfoSjdWCZvQPSKtGLVEH72 32VA1nikaRTIZEe4FDIKWjMrJJpKSYDZIUtMmg66KnQ+RN8TPTvlhUt4 NkGiIWeqwHP5eY4HhuCDaLezn4T640BB16usghh5AO+G5g==

DNSSEC 線上解析器

https://dnssec-analyzer.verisignlabs.com/community.cloudflare.com

DNSSEC Deployment

https://en.wikipedia.org/wiki/Domain_Name_System_Security_Extensions#Deployment

root zone 有支援

top-level domain 也絕大多數都有支援

絕大多數的網站都沒有啟用

很多域名註冊商不支援設定 DS record

沒人逼？

Google 和 Facebook 的網站沒有用 (現在還是)

DNSSEC 的機制可以拿來保證各種跟 domain 有關的紀錄

跟找 ip 沒有直接關聯的東西也可以

例如 TLS 的憑證

DANE (DNS-Based Authentication of Named Entities)

RFC 6698、RFC 7671

(「理論上」這套機制可以取代 CA 的角色)

https://en.wikipedia.org/wiki/DNS-based_Authentication_of_Named_Entities

DNSSEC 不能解決的問題

https://www.cloudflare.com/learning/dns/what-is-dns/

訊息未加密 & last mile 

"last mile"

關於 last mile 的解決辦法

用 tls/https 的隧道來傳遞 dns 訊息

DNS over TLS (DoT) (2016/05 RFC 7858、2018/03 RFC 8310)

DNS over HTTPS (DoH) (2018/10 RFC 8484)

"last mile"

https://www.cloudflare.com/learning/dns/what-is-dns/

resolver 支援度

https://en.wikipedia.org/wiki/Public_recursive_name_server

小總結

原始 DNS 協定沒有加密訊息、沒有簽章

後來 DNSSEC 加上了 nameserver 的簽章

這套機制不錯

不過他主要是在保護 resolver 不要被騙

沒有處理 user 跟 resolver 之間這段

目前也沒有什麼網站有啟用

之前還有其它一些增加 DNS 安全性的做法，可能沒下文？

last mile 要解決的話可能還是要用 DNS over TLS/HTTPS

參考資料

how dnssec works (cloudflare)

DNSSEC 解析器

DNSSEC wiki 

what-is-dns (cloudflare)

DNS Security

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