Rupa-rupa aspék operasi DNS geus sababaraha kali keuna ku pangarang dina sababaraha diterbitkeun salaku bagian tina blog. Dina waktos anu sami, tekenan utama nyaéta pikeun ningkatkeun kaamanan jasa Internét konci ieu.
Nepi ka ayeuna, sanajan kerentanan atra patalimarga DNS, anu masih, keur bagian paling, dikirimkeun dina jelas, mun lampah jahat dina bagian tina panyadia néangan pikeun ngaronjatkeun panghasilan maranéhanana ku embedding iklan dina eusi, agénsi kaamanan pamaréntah jeung carana ngawasan. kitu ogé saukur penjahat, prosés , sanajan ayana rupa-rupa téknologi saperti DNSSEC/DANE, DNScrypt, DNS-over-TLS jeung DNS-over-HTTPS, macet. Tur upami solusi server, sarta sawatara di antarana geus eksis keur rada lila, dipikawanoh lega tur sadia, rojongan maranéhanana ti software klien ninggalkeun loba kahayang.
Untungna, kaayaan geus robah. Khususna, pamekar browser Firefox populér ngeunaan rencana pikeun ngaktipkeun mode rojongan sacara standar (DoH) geura-giru. Ieu kedah ngabantosan ngajaga lalu lintas DNS pangguna WWW tina ancaman di luhur, tapi berpotensi ngenalkeun anu anyar.
1. Masalah DNS-over-HTTPS
Dina glance kahiji, mimiti bubuka massal DNS-over-HTTPS kana software Internet ngabalukarkeun ngan réaksi positif. Sanajan kitu, Iblis, sabab nyebutkeun, aya dina detil.
Masalah kahiji anu ngabatesan wengkuan pamakean nyebar DoH nyaéta fokusna ngan ukur dina lalu lintas wéb. Mémang, protokol HTTP sareng versi ayeuna HTTP/2, anu dumasar kana DoH, mangrupikeun dasar WWW. Tapi Internét sanés ngan ukur wéb. Aya seueur jasa populér, sapertos email, utusan instan, sistem transfer file, streaming multimedia, sareng sajabana, anu henteu nganggo HTTP. Ku kituna, sanajan persépsi ku loba DoH salaku panacea a, tétéla jadi iapplicable tanpa tambahan (jeung teu perlu) usaha pikeun nanaon lian ti téknologi browser. Ku jalan kitu, DNS-over-TLS Sigana calon anu langkung pantes pikeun peran ieu, anu ngalaksanakeun enkapsulasi lalu lintas DNS standar dina protokol TLS standar anu aman.
Masalah kadua, anu berpotensi langkung signifikan tibatan anu kahiji, nyaéta abandonment sabenerna desentralisasi alamiah tina DNS ku rarancang dina ni'mat ngagunakeun server DoH tunggal dieusian dina setélan browser. Khususna, Mozilla nyarankeun ngagunakeun jasa ti Cloudflare. Ladenan anu sami ogé diluncurkeun ku tokoh Internét anu sanés, khususna Google. Tétéla yén palaksanaan DNS-over-HTTPS dina bentuk anu ayeuna diusulkeun ngan ukur ningkatkeun gumantungna pangguna akhir dina jasa anu panggedéna. Henteu janten rahasia yén inpormasi anu tiasa disayogikeun ku analisa queries DNS tiasa ngumpulkeun langkung seueur data ngeunaan éta, ogé ningkatkeun akurasi sareng relevansi na.
Dina hal ieu, panulis éta sareng tetep ngadukung palaksanaan massal sanés tina DNS-over-HTTPS, tapi tina DNS-over-TLS sareng DNSSEC / DANE salaku universal, aman sareng henteu kondusif pikeun sentralisasi salajengna tina hartosna Internét. pikeun mastikeun kaamanan lalulintas DNS. Hanjakal, alesan atra, hiji teu bisa ngaharepkeun hiji bubuka gancang rojongan massa pikeun alternatif DoH kana software klien, sarta eta masih domain peminat téhnologi kaamanan.
Tapi saprak urang ayeuna gaduh DoH, naha henteu nganggo éta saatos kabur panjagaan poténsial ku korporasi ngalangkungan serverna ka server DNS-over-HTTPS urang sorangan?
2. protokol DNS-over-HTTPS
Lamun nempo standar ngajéntrékeun protokol DNS-over-HTTPS, anjeun tiasa ningali yén éta téh, kanyataanna, web API nu ngidinan Anjeun pikeun encapsulate pakét DNS baku dina protokol HTTP / 2. Ieu dilaksanakeun ngaliwatan lulugu HTTP husus, kitu ogé konversi format binér data DNS dikirimkeun (tingali. jeung dokumén saterusna) kana formulir nu ngidinan Anjeun pikeun ngirimkeun jeung narima eta, kitu ogé karya jeung metadata perlu.
Numutkeun standar, ngan ukur HTTP / 2 sareng sambungan TLS anu aman anu dirojong.
Ngirim pamundut DNS tiasa dilakukeun nganggo metode GET sareng POST standar. Dina kasus nu pertama, pamundut teh dirobah jadi string base64URL-disandikeun, sarta dina kadua, ngaliwatan awak pamundut POST dina formulir binér. Dina hal ieu, tipe data MIME husus dipaké salila pamundut DNS jeung respon aplikasi / dns-pesen.
root@eprove:~ # curl -H 'accept: application/dns-message' 'https://my.domaint/dns-query?dns=q80BAAABAAAAAAAAB2V4YW1wbGUDY29tAAABAAE' -v
* Trying 2001:100:200:300::400:443...
* TCP_NODELAY set
* Connected to eprove.net (2001:100:200:300::400) port 443 (#0)
* ALPN, offering h2
* ALPN, offering http/1.1
* successfully set certificate verify locations:
* CAfile: /usr/local/share/certs/ca-root-nss.crt
CApath: none
* TLSv1.3 (OUT), TLS handshake, Client hello (1):
* TLSv1.3 (IN), TLS handshake, Server hello (2):
* TLSv1.3 (IN), TLS handshake, Encrypted Extensions (8):
* TLSv1.3 (IN), TLS handshake, Certificate (11):
* TLSv1.3 (IN), TLS handshake, CERT verify (15):
* TLSv1.3 (IN), TLS handshake, Finished (20):
* TLSv1.3 (OUT), TLS change cipher, Change cipher spec (1):
* TLSv1.3 (OUT), TLS handshake, Finished (20):
* SSL connection using TLSv1.3 / TLS_AES_256_GCM_SHA384
* ALPN, server accepted to use h2
* Server certificate:
* subject: CN=my.domain
* start date: Jul 22 00:07:13 2019 GMT
* expire date: Oct 20 00:07:13 2019 GMT
* subjectAltName: host "my.domain" matched cert's "my.domain"
* issuer: C=US; O=Let's Encrypt; CN=Let's Encrypt Authority X3
* SSL certificate verify ok.
* Using HTTP2, server supports multi-use
* Connection state changed (HTTP/2 confirmed)
* Copying HTTP/2 data in stream buffer to connection buffer after upgrade: len=0
* Using Stream ID: 1 (easy handle 0x801441000)
> GET /dns-query?dns=q80BAAABAAAAAAAAB2V4YW1wbGUDY29tAAABAAE HTTP/2
> Host: eprove.net
> User-Agent: curl/7.65.3
> accept: application/dns-message
>
* TLSv1.3 (IN), TLS handshake, Newsession Ticket (4):
* Connection state changed (MAX_CONCURRENT_STREAMS == 100)!
< HTTP/2 200
< server: h2o/2.3.0-beta2
< content-type: application/dns-message
< cache-control: max-age=86274
< date: Thu, 12 Sep 2019 13:07:25 GMT
< strict-transport-security: max-age=15768000; includeSubDomains; preload
< content-length: 45
<
Warning: Binary output can mess up your terminal. Use "--output -" to tell
Warning: curl to output it to your terminal anyway, or consider "--output
Warning: <FILE>" to save to a file.
* Failed writing body (0 != 45)
* stopped the pause stream!
* Connection #0 to host eprove.net left intactOgé nengetan judul kontrol cache: dina respon ti web server. Dina parameter max-umur ngandung nilai TTL pikeun rékaman DNS anu dipulangkeun (atanapi nilai minimum upami sakumpulanana dipulangkeun).
Dumasar di luhur, fungsi hiji server DoH diwangun ku sababaraha tahap.
- Nampi pamundut HTTP. Upami ieu GET teras decode pakét tina encoding base64URL.
- Kirim pakét ieu ka server DNS.
- Meunang réspon ti server DNS
- Manggihan nilai TTL minimum dina rékaman narima.
- Balikkeun réspon ka klien via HTTP.
3. server DNS-over-HTTPS Anjeun sorangan
Cara pangbasajanna, panggancangna sareng paling efektif pikeun ngajalankeun server DNS-over-HTTPS anjeun nyalira nyaéta nganggo pangladén wéb HTTP/2. , ngeunaan anu parantos ditulis ku pangarang sacara ringkes (tingali "").
Pilihan ieu dirojong ku kanyataan yén sadaya kode server DoH anjeun tiasa dilaksanakeun sapinuhna nganggo juru basa anu terpadu kana H2O sorangan. . Salian perpustakaan standar, pikeun tukeur data sareng server DNS, anjeun peryogi perpustakaan Socket (mrbgem), anu, untungna, parantos kalebet dina versi pangembangan H2O 2.3.0-beta2 ayeuna. dina palabuhan FreeBSD. Nanging, henteu sesah pikeun nambihanana kana vérsi sateuacana ku cara ngakloning gudang kana katalog /deps saméméh kompilasi.
root@beta:~ # uname -v
FreeBSD 12.0-RELEASE-p10 GENERIC
root@beta:~ # cd /usr/ports/www/h2o
root@beta:/usr/ports/www/h2o # make extract
===> License MIT BSD2CLAUSE accepted by the user
===> h2o-2.2.6 depends on file: /usr/local/sbin/pkg - found
===> Fetching all distfiles required by h2o-2.2.6 for building
===> Extracting for h2o-2.2.6.
=> SHA256 Checksum OK for h2o-h2o-v2.2.6_GH0.tar.gz.
===> h2o-2.2.6 depends on file: /usr/local/bin/ruby26 - found
root@beta:/usr/ports/www/h2o # cd work/h2o-2.2.6/deps/
root@beta:/usr/ports/www/h2o/work/h2o-2.2.6/deps # git clone https://github.com/iij/mruby-socket.git
Клонирование в «mruby-socket»…
remote: Enumerating objects: 385, done.
remote: Total 385 (delta 0), reused 0 (delta 0), pack-reused 385
Получение объектов: 100% (385/385), 98.02 KiB | 647.00 KiB/s, готово.
Определение изменений: 100% (208/208), готово.
root@beta:/usr/ports/www/h2o/work/h2o-2.2.6/deps # ll
total 181
drwxr-xr-x 9 root wheel 18 12 авг. 16:09 brotli/
drwxr-xr-x 2 root wheel 4 12 авг. 16:09 cloexec/
drwxr-xr-x 2 root wheel 5 12 авг. 16:09 golombset/
drwxr-xr-x 4 root wheel 35 12 авг. 16:09 klib/
drwxr-xr-x 2 root wheel 5 12 авг. 16:09 libgkc/
drwxr-xr-x 4 root wheel 26 12 авг. 16:09 libyrmcds/
drwxr-xr-x 13 root wheel 32 12 авг. 16:09 mruby/
drwxr-xr-x 5 root wheel 11 12 авг. 16:09 mruby-digest/
drwxr-xr-x 5 root wheel 10 12 авг. 16:09 mruby-dir/
drwxr-xr-x 5 root wheel 10 12 авг. 16:09 mruby-env/
drwxr-xr-x 4 root wheel 9 12 авг. 16:09 mruby-errno/
drwxr-xr-x 5 root wheel 14 12 авг. 16:09 mruby-file-stat/
drwxr-xr-x 5 root wheel 10 12 авг. 16:09 mruby-iijson/
drwxr-xr-x 5 root wheel 11 12 авг. 16:09 mruby-input-stream/
drwxr-xr-x 6 root wheel 11 12 авг. 16:09 mruby-io/
drwxr-xr-x 5 root wheel 10 12 авг. 16:09 mruby-onig-regexp/
drwxr-xr-x 4 root wheel 10 12 авг. 16:09 mruby-pack/
drwxr-xr-x 5 root wheel 10 12 авг. 16:09 mruby-require/
drwxr-xr-x 6 root wheel 10 12 сент. 16:10 mruby-socket/
drwxr-xr-x 2 root wheel 9 12 авг. 16:09 neverbleed/
drwxr-xr-x 2 root wheel 13 12 авг. 16:09 picohttpparser/
drwxr-xr-x 2 root wheel 4 12 авг. 16:09 picotest/
drwxr-xr-x 9 root wheel 16 12 авг. 16:09 picotls/
drwxr-xr-x 4 root wheel 8 12 авг. 16:09 ssl-conservatory/
drwxr-xr-x 8 root wheel 18 12 авг. 16:09 yaml/
drwxr-xr-x 2 root wheel 8 12 авг. 16:09 yoml/
root@beta:/usr/ports/www/h2o/work/h2o-2.2.6/deps # cd ../../..
root@beta:/usr/ports/www/h2o # make install clean
...Konfigurasi pangladén wéb umumna standar.
root@beta:/usr/ports/www/h2o # cd /usr/local/etc/h2o/
root@beta:/usr/local/etc/h2o # cat h2o.conf
# this sample config gives you a feel for how h2o can be used
# and a high-security configuration for TLS and HTTP headers
# see https://h2o.examp1e.net/ for detailed documentation
# and h2o --help for command-line options and settings
# v.20180207 (c)2018 by Max Kostikov http://kostikov.co e-mail: [email protected]
user: www
pid-file: /var/run/h2o.pid
access-log:
path: /var/log/h2o/h2o-access.log
format: "%h %v %l %u %t "%r" %s %b "%{Referer}i" "%{User-agent}i""
error-log: /var/log/h2o/h2o-error.log
expires: off
compress: on
file.dirlisting: off
file.send-compressed: on
file.index: [ 'index.html', 'index.php' ]
listen:
port: 80
listen:
port: 443
ssl:
cipher-suite: ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305:ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:DHE-RSA-AES128-GCM-SHA256:DHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-AES128-SHA256:ECDHE-RSA-AES128-SHA256:ECDHE-ECDSA-AES128-SHA:ECDHE-RSA-AES256-SHA384:ECDHE-RSA-AES128-SHA:ECDHE-ECDSA-AES256-SHA384:ECDHE-ECDSA-AES256-SHA:ECDHE-RSA-AES256-SHA:DHE-RSA-AES128-SHA256:DHE-RSA-AES128-SHA:DHE-RSA-AES256-SHA256:DHE-RSA-AES256-SHA:ECDHE-ECDSA-DES-CBC3-SHA:ECDHE-RSA-DES-CBC3-SHA:EDH-RSA-DES-CBC3-SHA:AES128-GCM-SHA256:AES256-GCM-SHA384:AES128-SHA256:AES256-SHA256:AES128-SHA:AES256-SHA:DES-CBC3-SHA:!DSS
cipher-preference: server
dh-file: /etc/ssl/dhparams.pem
certificate-file: /usr/local/etc/letsencrypt/live/eprove.net/fullchain.pem
key-file: /usr/local/etc/letsencrypt/live/my.domain/privkey.pem
hosts:
"*.my.domain":
paths: &go_tls
"/":
redirect:
status: 301
url: https://my.domain/
"my.domain:80":
paths: *go_tls
"my.domain:443":
header.add: "Strict-Transport-Security: max-age=15768000; includeSubDomains; preload"
paths:
"/dns-query":
mruby.handler-file: /usr/local/etc/h2o/h2odoh.rbHiji-hijina iwal nyaéta panangan URL /dns-query nu server DNS-over-HTTPS kami, ditulis dina mruby sarta disebut ngaliwatan pilihan Handler, sabenerna tanggung jawab. mruby.handler-file.
root@beta:/usr/local/etc/h2o # cat h2odoh.rb
# H2O HTTP/2 web server as DNS-over-HTTP service
# v.20190908 (c)2018-2019 Max Kostikov https://kostikov.co e-mail: [email protected]
proc {|env|
if env['HTTP_ACCEPT'] == "application/dns-message"
case env['REQUEST_METHOD']
when "GET"
req = env['QUERY_STRING'].gsub(/^dns=/,'')
# base64URL decode
req = req.tr("-_", "+/")
if !req.end_with?("=") && req.length % 4 != 0
req = req.ljust((req.length + 3) & ~3, "=")
end
req = req.unpack1("m")
when "POST"
req = env['rack.input'].read
else
req = ""
end
if req.empty?
[400, { 'content-type' => 'text/plain' }, [ "Bad Request" ]]
else
# --- ask DNS server
sock = UDPSocket.new
sock.connect("localhost", 53)
sock.send(req, 0)
str = sock.recv(4096)
sock.close
# --- find lowest TTL in response
nans = str[6, 2].unpack1('n') # number of answers
if nans > 0 # no DNS failure
shift = 12
ttl = 0
while nans > 0
# process domain name compression
if str[shift].unpack1("C") < 192
shift = str.index("x00", shift) + 5
if ttl == 0 # skip question section
next
end
end
shift += 6
curttl = str[shift, 4].unpack1('N')
shift += str[shift + 4, 2].unpack1('n') + 6 # responce data size
if ttl == 0 or ttl > curttl
ttl = curttl
end
nans -= 1
end
cc = 'max-age=' + ttl.to_s
else
cc = 'no-cache'
end
[200, { 'content-type' => 'application/dns-message', 'content-length' => str.size, 'cache-control' => cc }, [ str ] ]
end
else
[415, { 'content-type' => 'text/plain' }, [ "Unsupported Media Type" ]]
end
}Punten dicatet yén server cache lokal tanggung jawab pikeun ngolah pakét DNS, dina hal ieu tina distribusi FreeBSD standar. Tina sudut pandang kaamanan, ieu mangrupikeun solusi anu optimal. Sanajan kitu, euweuh nyegah anjeun ti ngaganti localhost ka alamat DNS anu béda anu anjeun badé dianggo.
root@beta:/usr/local/etc/h2o # local-unbound verison
usage: local-unbound [options]
start unbound daemon DNS resolver.
-h this help
-c file config file to read instead of /var/unbound/unbound.conf
file format is described in unbound.conf(5).
-d do not fork into the background.
-p do not create a pidfile.
-v verbose (more times to increase verbosity)
Version 1.8.1
linked libs: mini-event internal (it uses select), OpenSSL 1.1.1a-freebsd 20 Nov 2018
linked modules: dns64 respip validator iterator
BSD licensed, see LICENSE in source package for details.
Report bugs to [email protected]
root@eprove:/usr/local/etc/h2o # sockstat -46 | grep unbound
unbound local-unbo 69749 3 udp6 ::1:53 *:*
unbound local-unbo 69749 4 tcp6 ::1:53 *:*
unbound local-unbo 69749 5 udp4 127.0.0.1:53 *:*
unbound local-unbo 69749 6 tcp4 127.0.0.1:53 *:*Sadaya anu tetep nyaéta ngabalikan deui H2O sareng ningali naon asalna.
root@beta:/usr/local/etc/h2o # service h2o restart
Stopping h2o.
Waiting for PIDS: 69871.
Starting h2o.
start_server (pid:70532) starting now...4. Nguji
Janten, hayu urang parios hasilna ku ngirim deui pamundut uji sareng ningali lalu lintas jaringan nganggo utilitas tcpdump.
root@beta/usr/local/etc/h2o # curl -H 'accept: application/dns-message' 'https://my.domain/dns-query?dns=q80BAAABAAAAAAAAB2V4YW1wbGUDY29tAAABAAE'
Warning: Binary output can mess up your terminal. Use "--output -" to tell
Warning: curl to output it to your terminal anyway, or consider "--output
Warning: <FILE>" to save to a file.
...
root@beta:~ # tcpdump -n -i lo0 udp port 53 -xx -XX -vv
tcpdump: listening on lo0, link-type NULL (BSD loopback), capture size 262144 bytes
16:32:40.420831 IP (tos 0x0, ttl 64, id 37575, offset 0, flags [none], proto UDP (17), length 57, bad cksum 0 (->e9ea)!)
127.0.0.1.21070 > 127.0.0.1.53: [bad udp cksum 0xfe38 -> 0x33e3!] 43981+ A? example.com. (29)
0x0000: 0200 0000 4500 0039 92c7 0000 4011 0000 ....E..9....@...
0x0010: 7f00 0001 7f00 0001 524e 0035 0025 fe38 ........RN.5.%.8
0x0020: abcd 0100 0001 0000 0000 0000 0765 7861 .............exa
0x0030: 6d70 6c65 0363 6f6d 0000 0100 01 mple.com.....
16:32:40.796507 IP (tos 0x0, ttl 64, id 37590, offset 0, flags [none], proto UDP (17), length 73, bad cksum 0 (->e9cb)!)
127.0.0.1.53 > 127.0.0.1.21070: [bad udp cksum 0xfe48 -> 0x43fa!] 43981 q: A? example.com. 1/0/0 example.com. A 93.184.216.34 (45)
0x0000: 0200 0000 4500 0049 92d6 0000 4011 0000 ....E..I....@...
0x0010: 7f00 0001 7f00 0001 0035 524e 0035 fe48 .........5RN.5.H
0x0020: abcd 8180 0001 0001 0000 0000 0765 7861 .............exa
0x0030: 6d70 6c65 0363 6f6d 0000 0100 01c0 0c00 mple.com........
0x0040: 0100 0100 0151 8000 045d b8d8 22 .....Q...].."
^C
2 packets captured
23 packets received by filter
0 packets dropped by kernelKaluaran nunjukkeun kumaha pamundut pikeun ngabéréskeun alamat example.com ditampi tur hasil diolah ku server DNS.
Ayeuna anu tetep nyaéta pikeun ngaktipkeun server kami dina browser Firefox. Jang ngalampahkeun ieu, anjeun kudu ngarobah sababaraha setélan dina kaca konfigurasi ngeunaan: config.
Anu mimiti, ieu mangrupikeun alamat API kami dimana browser bakal menta inpormasi DNS network.trr.uri. Disarankeun ogé nangtukeun IP domain ti URL ieu pikeun resolusi IP aman ngagunakeun browser sorangan tanpa ngakses DNS di network.trr.bootstrapAddress. Sarta pamustunganana, parameter sorangan network.trr.mode kaasup pamakéan DoH. Nyetel nilai ka "3" bakal maksa browser ngagunakeun éksklusif DNS-over-HTTPS pikeun resolusi ngaran, sedengkeun nu leuwih dipercaya jeung aman "2" bakal masihan prioritas ka DoH, ninggalkeun lookup DNS standar salaku pilihan fallback.
5. UNTUNG!
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