Divès aspè nan operasyon dns yo te deja repete manyen pa otè a nan yon kantite pibliye kòm yon pati nan blog la. An menm tan an, anfaz prensipal la te toujou sou amelyore sekirite sèvis entènèt kle sa a.
Jiska dènyèman, malgre vilnerabilite evidan nan trafik DNS, ki toujou, pou pati nan, transmèt nan klè, nan aksyon move sou pati nan founisè yo k ap chèche ogmante revni yo nan entegre piblisite nan kontni, ajans sekirite gouvènman yo ak sansi, osi byen ke tou senpleman kriminèl, pwosesis la , malgre prezans plizyè teknoloji tankou DNSSEC/DANE, DNScrypt, DNS-over-TLS ak DNS-over-HTTPS, bloke. Men, si solisyon sèvè, ak kèk nan yo te egziste pou yon tan long, yo lajman li te ye ak disponib, sipò yo nan lojisyèl kliyan kite anpil yo dwe vle.
Erezman, sitiyasyon an ap chanje. An patikilye, devlopè popilè Firefox navigatè a sou plan yo pèmèt mòd sipò pa default (DoH) byento. Sa a ta dwe ede pwoteje trafik DNS itilizatè WWW a kont menas ki anwo yo, men li kapab entwodui nouvo menas.
1. DNS-sou-HTTPS pwoblèm
Nan premye gade, kòmansman an mas entwodiksyon DNS-sou-HTTPS nan lojisyèl entènèt lakòz sèlman yon reyaksyon pozitif. Sepandan, dyab la, jan yo di, se nan detay yo.
Premye pwoblèm ki limite sijè ki abòde itilizasyon DoH a se konsantre sèlman sou trafik entènèt. Vreman vre, pwotokòl HTTP a ak vèsyon aktyèl li HTTP/2, sou ki DoH baze, se baz WWW la. Men, entènèt la se pa sèlman entènèt la. Gen anpil sèvis popilè, tankou imèl, mesaje enstantane, sistèm transfè dosye, difizyon miltimedya, elatriye, ki pa sèvi ak HTTP. Kidonk, malgre pèsepsyon anpil nan DoH kòm yon mirak, li vire soti yo pa aplikab san efò adisyonèl (ak nesesè) pou nenpòt lòt bagay pase teknoloji navigatè. By wout la, DNS-over-TLS sanble yon kandida pi plis merite pou wòl sa a, ki aplike enkapsulasyon trafik DNS estanda nan pwotokòl TLS estanda ki an sekirite.
Dezyèm pwoblèm nan, ki se potansyèlman pi enpòtan pase premye a, se abandon aktyèl la nan nannan desantralizasyon DNS pa konsepsyon an favè itilize yon sèl sèvè DoH espesifye nan paramèt navigatè a. An patikilye, Mozilla sijere lè l sèvi avèk yon sèvis nan Cloudflare. Yon sèvis menm jan an te lanse tou pa lòt figi enpòtan entènèt, an patikilye Google. Li sanble ke aplikasyon an nan DNS-sou-HTTPS nan fòm lan nan ki li se kounye a pwopoze sèlman ogmante depandans nan itilizatè final yo sou pi gwo sèvis yo. Li pa sekrè pou enfòmasyon ke analiz de requêtes DNS ka bay ka kolekte menm plis done sou li, osi byen ke ogmante presizyon li yo ak enpòtans.
Nan sans sa a, otè a te epi li rete yon sipòtè nan aplikasyon an mas pa nan DNS-sou-HTTPS, men nan DNS-sou-TLS ansanm ak DNSSEC/DANE kòm yon inivèsèl, an sekirite epi yo pa fezab nan plis santralizasyon nan mwayen Entènèt la. pou asire sekirite trafik DNS. Malerezman, pou rezon evidan, yon moun pa ka atann yon entwodiksyon rapid nan sipò mas pou altènativ DoH nan lojisyèl kliyan, epi li se toujou domèn nan amater teknoloji sekirite.
Men, depi kounye a nou gen DoH, poukisa nou pa sèvi ak li apre yo fin chape siveyans potansyèl pa kòporasyon atravè serveurs yo nan pwòp sèvè DNS-sou-HTTPS nou an?
2. DNS-sou-HTTPS pwotokòl
Si ou gade nan estanda a ki dekri pwotokòl DNS-sou-HTTPS la, ou ka wè ke li se, an reyalite, yon API entènèt ki pèmèt ou ankapsile yon pake DNS estanda nan pwotokòl HTTP/2 la. Sa a se aplike nan tèt espesyal HTTP, osi byen ke konvèsyon nan fòma binè done DNS transmèt (gade. ak dokiman ki vin apre) nan yon fòm ki pèmèt ou transmèt ak resevwa yo, osi byen ke travay ak metadata ki nesesè yo.
Dapre estanda a, sèlman HTTP/2 ak yon koneksyon TLS an sekirite yo sipòte.
Voye yon demann DNS ka fè lè l sèvi avèk metòd estanda GET ak POST. Nan premye ka a, demann lan transfòme nan yon kòd base64URL-kode, ak nan dezyèm lan, atravè kò a nan demann POST la nan fòm binè. Nan ka sa a, yo itilize yon kalite done espesyal MIME pandan demann ak repons DNS la aplikasyon/dns-mesaj.
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 intactEpitou peye atansyon sou tit la kachèt-kontwòl: nan repons ki soti nan sèvè entènèt la. Nan paramèt la laj maksimòm gen valè TTL pou dosye DNS ke yo te retounen (oswa valè minimòm si yo te retounen yon seri yo).
Dapre sa ki anwo a, fonksyone yon sèvè DoH konsiste de plizyè etap.
- Resevwa yon demann HTTP. Si sa a se yon GET Lè sa a, dekode pake a soti nan kodaj base64URL.
- Voye pake sa a sou sèvè dns la.
- Jwenn yon repons nan men sèvè dns la
- Jwenn valè TTL minimòm nan dosye ou resevwa yo.
- Retounen yon repons bay kliyan an atravè HTTP.
3. Pwòp sèvè DNS-sou-HTTPS ou
Fason ki pi senp, pi rapid ak pi efikas pou kouri pwòp sèvè DNS-sou-HTTPS ou se sèvi ak yon sèvè entènèt HTTP/2. , sou ki otè a te deja ekri yon ti tan (gade "").
Chwa sa a sipòte pa lefèt ke tout kòd pwòp sèvè DoH ou a ka konplètman aplike lè l sèvi avèk entèprèt la entegre nan H2O tèt li. . Anplis de bibliyotèk estanda yo, pou fè echanj done ak sèvè dns la, ou bezwen bibliyotèk Socket (mrbgem), ki, erezman, deja enkli nan vèsyon devlopman aktyèl H2O 2.3.0-beta2. nan pò FreeBSD. Sepandan, li pa difisil pou ajoute li nan nenpòt vèsyon anvan yo pa klonaj repozitwa a nan katalòg la /deps anvan konpilasyon.
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
...Konfigirasyon sèvè entènèt la jeneralman estanda.
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.rbSèl eksepsyon se adrès URL la /dns-query pou ki sèvè DNS-sou-HTTPS nou an, ki ekri an mruby epi ki rele nan opsyon moun kap okipe a, se aktyèlman responsab 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
}Tanpri sonje ke sèvè kachèt lokal la responsab pou trete pake DNS, nan ka sa a soti nan distribisyon estanda FreeBSD. Soti nan yon pwen de vi sekirite, sa a se solisyon an pi bon. Sepandan, pa gen anyen ki anpeche w ranplase lokalost nan yon adrès DNS diferan ke ou gen entansyon itilize.
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 *:*Tout sa ki rete se rekòmanse H2O epi wè sa ki soti nan li.
root@beta:/usr/local/etc/h2o # service h2o restart
Stopping h2o.
Waiting for PIDS: 69871.
Starting h2o.
start_server (pid:70532) starting now...4. Tès
Se konsa, ann tcheke rezilta yo lè nou voye yon demann tès ankò epi gade trafik rezo a lè l sèvi avèk sèvis piblik la 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 kernelPwodiksyon an montre ki jan demann lan rezoud adrès la example.com te resevwa ak trete avèk siksè pa sèvè a dns.
Koulye a, tout sa ki rete se aktive sèvè nou an nan navigatè Firefox la. Pou fè sa, ou bezwen chanje plizyè paramèt nan paj konfigirasyon yo sou: config.
Premyèman, sa a se adrès API nou an kote navigatè a pral mande enfòmasyon DNS network.trr.uri. Li rekòmande tou pou presize IP domèn nan URL sa a pou rezolisyon IP an sekirite lè l sèvi avèk navigatè a li menm san yo pa gen aksè DNS nan network.trr.bootstrapAddress. Epi finalman, paramèt nan tèt li rezo.trr.mode ki gen ladan itilizasyon DoH. Mete valè a "3" pral fòse navigatè a sèvi ak sèlman DNS-sou-HTTPS pou rezolisyon non, pandan y ap "2" ki pi serye ak an sekirite pral bay DoH priyorite, kite rechèch DNS estanda a kòm yon opsyon sere.
5. Pwofi!
Èske atik la te itil? Lè sa a, tanpri pa timid epi sipòte ak lajan atravè fòm donasyon an (anba a).
Sous: www.habr.com