DNS operatsiyasining turli jihatlari muallif tomonidan bir necha bor qayta-qayta to'xtalib o'tgan blogning bir qismi sifatida nashr etilgan. Shu bilan birga, asosiy e'tibor doimo ushbu asosiy Internet xizmatining xavfsizligini oshirishga qaratilgan.
So'nggi paytgacha, aksariyat hollarda provayderlar tomonidan reklamani kontentga joylashtirish orqali o'z daromadlarini oshirishga intilayotgan, davlat xavfsizlik idoralari va tsenzuraning zararli harakatlariga qarshi DNS-trafikning aniq zaifligiga qaramay, shuningdek, oddiy jinoyatchilar, jarayon , DNSSEC/DANE, DNScrypt, DNS-over-TLS va DNS-over-HTTPS kabi turli texnologiyalar mavjudligiga qaramasdan, to'xtab qoldi. Agar server echimlari va ularning ba'zilari ancha vaqtdan beri mavjud bo'lsa, keng ma'lum va mavjud bo'lsa, ularning mijoz dasturiy ta'minotidan ko'mak ko'p narsani xohlamaydi.
Yaxshiyamki, vaziyat o'zgarmoqda. Xususan, mashhur Firefox brauzerini ishlab chiquvchilar sukut bo'yicha qo'llab-quvvatlash rejimini yoqish rejalari haqida (DoH) tez orada. Bu WWW foydalanuvchisining DNS trafigini yuqoridagi tahdidlardan himoya qilishga yordam berishi kerak, lekin yangilarini ham kiritishi mumkin.
1. DNS-over-HTTPS bilan bog'liq muammolar
Bir qarashda, DNS-over-HTTPS-ning Internet-dasturiy ta'minotiga ommaviy joriy etilishi faqat ijobiy reaktsiyaga sabab bo'ladi. Biroq, shayton, ular aytganidek, tafsilotlarda.
DoHning keng qo'llanilishi doirasini cheklaydigan birinchi muammo uning faqat veb-trafikga qaratilganligidir. Haqiqatan ham, HTTP protokoli va uning DoH asoslangan joriy versiyasi HTTP/2 WWW asosi hisoblanadi. Ammo Internet shunchaki tarmoq emas. HTTP dan foydalanmaydigan elektron pochta, turli lahzali messenjerlar, fayl uzatish tizimlari, multimedia oqimlari va boshqalar kabi ko'plab mashhur xizmatlar mavjud. Shunday qilib, ko'pchilik DoH tomonidan panatseya sifatida qabul qilinishiga qaramay, u brauzer texnologiyalaridan boshqa hech qanday qo'shimcha (va keraksiz) harakatlarsiz qo'llanilmaydi. Aytgancha, DNS-over-TLS ushbu rol uchun ancha munosib nomzodga o'xshaydi, u xavfsiz standart TLS protokolida standart DNS trafigini inkapsulyatsiya qilishni amalga oshiradi.
Ikkinchi muammo, birinchisiga qaraganda ancha ahamiyatli bo'lib, brauzer sozlamalarida ko'rsatilgan yagona DoH serveridan foydalanish foydasiga dizayn bo'yicha DNS-ning o'ziga xos markazsizlashtirilishidan haqiqiy voz kechishdir. Xususan, Mozilla Cloudflare xizmatidan foydalanishni taklif qiladi. Shunga o'xshash xizmat boshqa taniqli Internet vakillari, xususan Google tomonidan ham ishga tushirildi. Ma'lum bo'lishicha, DNS-over-HTTPS-ni hozirda taklif qilingan shaklda amalga oshirish oxirgi foydalanuvchilarning eng yirik xizmatlarga bog'liqligini oshiradi. Hech kimga sir emaski, DNS so'rovlarini tahlil qilish mumkin bo'lgan ma'lumotlar u haqida ko'proq ma'lumotlarni to'plashi, shuningdek uning aniqligi va dolzarbligini oshirishi mumkin.
Shu munosabat bilan, muallif DNS-over-HTTPS emas, balki DNS-over-TLS-ni DNSSEC/DANE bilan birgalikda universal, xavfsiz va Internet vositalarini yanada markazlashtirishga yordam bermaydigan ommaviy joriy etish tarafdori bo'lgan va shunday bo'lib qoladi. DNS-trafik xavfsizligini ta'minlash uchun. Afsuski, aniq sabablarga ko'ra, mijoz dasturiy ta'minotiga DoH alternativalarini ommaviy qo'llab-quvvatlashni tez joriy etishni kutish mumkin emas va bu hali ham xavfsizlik texnologiyalari ishqibozlari sohasi.
Ammo bizda DoH bor ekan, nega korporatsiyalar o'z serverlari orqali o'zimizning DNS-over-HTTPS serverimizga potentsial kuzatuvidan qochib, undan foydalanmasligimiz kerak?
2. DNS-over-HTTPS protokoli
Agar siz standartga qarasangiz DNS-over-HTTPS protokolini tavsiflab, bu, aslida, HTTP/2 protokolida standart DNS paketini inkapsulyatsiya qilish imkonini beruvchi veb-API ekanligini ko'rishingiz mumkin. Bu maxsus HTTP sarlavhalari, shuningdek uzatilgan DNS ma'lumotlarining ikkilik formatini konvertatsiya qilish orqali amalga oshiriladi (qarang. va keyingi hujjatlar) ularni uzatish va qabul qilish, shuningdek zarur metama'lumotlar bilan ishlash imkonini beruvchi shaklga kiriting.
Standartga ko'ra, faqat HTTP/2 va xavfsiz TLS ulanishi qo'llab-quvvatlanadi.
DNS so'rovini yuborish standart GET va POST usullari yordamida amalga oshirilishi mumkin. Birinchi holda, so'rov base64URL-kodlangan qatorga, ikkinchisida esa POST so'rovining asosiy qismi orqali ikkilik shaklda o'zgartiriladi. Bunday holda, DNS so'rovi va javobi paytida maxsus MIME ma'lumotlar turi qo'llaniladi ilova/dns-xabar.
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 intactSarlavhaga ham e'tibor bering kesh-nazorat: veb-serverdan javobda. Parametrda maksimal yosh Qaytarilayotgan DNS yozuvi uchun TTL qiymatini (yoki ularning to'plami qaytarilayotgan bo'lsa, minimal qiymatni) o'z ichiga oladi.
Yuqoridagilardan kelib chiqqan holda, DoH serverining ishlashi bir necha bosqichlardan iborat.
- HTTP so'rovini qabul qiling. Agar bu GET bo'lsa, paketni base64URL kodlashdan dekodlang.
- Ushbu paketni DNS serveriga yuboring.
- DNS serveridan javob oling
- Qabul qilingan yozuvlarda minimal TTL qiymatini toping.
- HTTP orqali mijozga javob qaytaring.
3. O'zingizning DNS-over-HTTPS serveringiz
HTTP/2 veb-serveridan foydalanishdir. , bu haqda muallif allaqachon qisqacha yozgan (qarang: "").
Ushbu tanlov sizning DoH serveringizning barcha kodlari H2O ning o'ziga integratsiyalangan tarjimon yordamida to'liq amalga oshirilishi mumkinligi bilan qo'llab-quvvatlanadi. . Standart kutubxonalarga qo'shimcha ravishda, DNS-server bilan ma'lumot almashish uchun sizga (mrbgem) Socket kutubxonasi kerak bo'ladi, u xayriyatki, H2O 2.3.0-beta2 ning joriy ishlab chiqish versiyasiga kiritilgan. FreeBSD portlarida. Biroq, omborni klonlash orqali uni har qanday oldingi versiyaga qo'shish qiyin emas katalogga /deps kompilyatsiya qilishdan oldin.
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
...Veb-server konfiguratsiyasi odatda standartdir.
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.rbFaqatgina istisno URL ishlov beruvchisidir /dns-so'rov Buning uchun mruby-da yozilgan va ishlov beruvchi opsiyasi orqali chaqirilgan DNS-over-HTTPS serverimiz aslida javobgardir. mruby.handler-fayl.
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
}E'tibor bering, mahalliy keshlash serveri bu holda DNS paketlarini qayta ishlash uchun javobgardir standart FreeBSD distributividan. Xavfsizlik nuqtai nazaridan, bu eng maqbul echimdir. Biroq, hech narsa sizni almashtirishga to'sqinlik qilmaydi localhost foydalanmoqchi bo'lgan boshqa DNS manziliga.
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 *:*H2O ni qayta ishga tushirish va undan nima bo'lishini ko'rish qoladi.
root@beta:/usr/local/etc/h2o # service h2o restart
Stopping h2o.
Waiting for PIDS: 69871.
Starting h2o.
start_server (pid:70532) starting now...4. Sinov
Shunday qilib, keling, test so'rovini qayta yuborish va yordamchi dastur yordamida tarmoq trafigini ko'rib chiqish orqali natijalarni tekshiramiz 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 kernelChiqish manzilni qanday hal qilish bo'yicha so'rovni ko'rsatadi example.com qabul qilindi va DNS server tomonidan muvaffaqiyatli qayta ishlandi.
Endi Firefox brauzerida serverimizni faollashtirishgina qoladi. Buning uchun konfiguratsiya sahifalarida bir nechta sozlamalarni o'zgartirishingiz kerak haqida: config.
Birinchidan, bu bizning API manzili bo'lib, unda brauzer DNS ma'lumotlarini so'raydi network.trr.uri. Shuningdek, DNS-ga kirmasdan brauzerning o'zi yordamida xavfsiz IP ruxsati uchun ushbu URL-dan domen IP-ni ko'rsatish tavsiya etiladi. network.trr.bootstrapAddress. Va nihoyat, parametrning o'zi network.trr.mode shu jumladan DoH dan foydalanish. Qiymatning "3" ga o'rnatilishi brauzerni nomni aniqlash uchun faqat DNS-over-HTTPS-dan foydalanishga majbur qiladi, ishonchliroq va xavfsizroq "2" esa DoH-ga ustunlik beradi va standart DNS qidiruvini zaxira variant sifatida qoldiradi.
5. FOYDA!
Maqola foydali bo'ldimi? Keyin uyalmang va xayr-ehson shakli orqali (quyida) pul bilan qo'llab-quvvatlang.
Manba: www.habr.com