Diversi aspetti tal-operat tad-DNS diġà ġew mimsus ripetutament mill-awtur f'numru ta' ippubblikat bħala parti mill-blog. Fl-istess ħin, l-enfasi ewlenija dejjem kienet fuq it-titjib tas-sigurtà ta’ dan is-servizz ewlieni tal-Internet.
Sa ftit ilu, minkejja l-vulnerabbiltà ovvja tat-traffiku tad-DNS, li għadu, fil-biċċa l-kbira, trażmess b’mod ċar, għal azzjonijiet malizzjużi min-naħa tal-fornituri li jfittxu li jżidu d-dħul tagħhom billi jinkorporaw reklamar fil-kontenut, l-aġenziji tas-sigurtà tal-gvern u ċ-ċensura, kif ukoll sempliċement kriminali, il-proċess , minkejja l-preżenza ta 'diversi teknoloġiji bħal DNSSEC/DANE, DNScrypt, DNS-over-TLS u DNS-over-HTTPS, waqfu. U jekk is-soluzzjonijiet tas-server, u xi wħud minnhom ilhom jeżistu għal żmien pjuttost twil, huma magħrufa u disponibbli b'mod wiesa ', l-appoġġ tagħhom minn softwer tal-klijent iħalli ħafna x'jixtieq.
Fortunatament, is-sitwazzjoni qed tinbidel. B'mod partikolari, l-iżviluppaturi tal-browser Firefox popolari dwar pjanijiet biex il-modalità ta' appoġġ tiġi attivata b'mod awtomatiku (DoH) dalwaqt. Dan għandu jgħin biex jipproteġi t-traffiku DNS tal-utent WWW mit-theddid ta 'hawn fuq, iżda jista' potenzjalment jintroduċi oħrajn ġodda.
1. Problemi DNS-over-HTTPS
L-ewwel daqqa t'għajn, l-introduzzjoni tal-massa tal-bidu ta 'DNS-over-HTTPS fis-softwer tal-Internet tikkawża biss reazzjoni pożittiva. Madankollu, ix-xitan, kif jgħidu, jinsab fid-dettalji.
L-ewwel problema li tillimita l-ambitu tal-użu mifrux tad-DoH hija l-fokus tagħha biss fuq it-traffiku tal-web. Tabilħaqq, il-protokoll HTTP u l-verżjoni attwali tiegħu HTTP/2, li fuqhom huwa bbażat id-DoH, huma l-bażi tal-WWW. Iżda l-Internet mhuwiex biss il-web. Hemm ħafna servizzi popolari, bħal email, messaġġiera instantanja varji, sistemi ta 'trasferiment ta' fajls, streaming multimedjali, eċċ., li ma jużawx HTTP. Għalhekk, minkejja l-perċezzjoni minn ħafna ta 'DoH bħala rimedju, jirriżulta li huwa inapplikabbli mingħajr sforz addizzjonali (u mhux meħtieġ) għal xi ħaġa oħra għajr it-teknoloġiji tal-browser. Mill-mod, DNS-over-TLS jidher kandidat ħafna aktar denju għal dan ir-rwol, li jimplimenta l-inkapsulament tat-traffiku DNS standard fil-protokoll TLS standard sigur.
It-tieni problema, li hija potenzjalment ħafna aktar sinifikanti mill-ewwel, hija l-abbandun attwali tad-deċentralizzazzjoni inerenti tad-DNS bid-disinn favur l-użu ta 'server DoH wieħed speċifikat fis-settings tal-browser. B'mod partikolari, Mozilla jissuġġerixxi li tuża servizz minn Cloudflare. Servizz simili tnieda wkoll minn figuri prominenti oħra tal-Internet, b’mod partikolari Google. Jirriżulta li l-implimentazzjoni tad-DNS-over-HTTPS fil-forma li bħalissa hija proposta biss iżżid id-dipendenza tal-utenti finali fuq l-akbar servizzi. Mhuwiex sigriet li l-informazzjoni li l-analiżi tal-mistoqsijiet DNS tista 'tipprovdi tista' tiġbor saħansitra aktar dejta dwarha, kif ukoll iżżid l-eżattezza u r-rilevanza tagħha.
F'dan ir-rigward, l-awtur kien u jibqa' sostenitur tal-implimentazzjoni tal-massa mhux ta' DNS-over-HTTPS, iżda ta' DNS-over-TLS flimkien ma' DNSSEC/DANE bħala mezz universali, sigur u li ma jwassalx għal aktar ċentralizzazzjoni tal-Internet. biex tiġi żgurata s-sigurtà tat-traffiku DNS. Sfortunatament, għal raġunijiet ovvji, wieħed ma jistax jistenna introduzzjoni rapida ta 'appoġġ tal-massa għal alternattivi DoH fis-softwer tal-klijent, u għadu d-dominju tad-dilettanti tat-teknoloġija tas-sigurtà.
Imma peress li issa għandna DoH, għaliex ma tużahx wara li jaħarbu minn sorveljanza potenzjali minn korporazzjonijiet permezz tas-servers tagħhom għas-server DNS-over-HTTPS tagħna stess?
2. Protokoll DNS-over-HTTPS
Jekk tħares lejn l-istandard tiddeskrivi l-protokoll DNS-over-HTTPS, tista 'tara li hija, fil-fatt, API tal-web li tippermettilek li tiġbor pakkett DNS standard fil-protokoll HTTP/2. Dan huwa implimentat permezz ta' headers HTTP speċjali, kif ukoll il-konverżjoni tal-format binarju tad-dejta DNS trażmessa (ara. u dokumenti sussegwenti) f’forma li tippermettilek tittrasmettihom u tirċevihom, kif ukoll taħdem bil-metadata meħtieġa.
Skont l-istandard, huma appoġġjati biss HTTP/2 u konnessjoni TLS sigura.
It-trażmissjoni ta' talba DNS tista' ssir bl-użu tal-metodi standard GET u POST. Fl-ewwel każ, it-talba tinbidel fi string kodifikata b'base64URL, u fit-tieni, permezz tal-korp tat-talba POST f'forma binarja. F'dan il-każ, jintuża tip ta' dejta MIME speċjali waqt it-talba u r-rispons tad-DNS applikazzjoni/dns-messagg.
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 intactOqgħod attent ukoll għat-titlu kontroll tal-cache: fir-rispons mis-server tal-web. Fil-parametru max-età fih il-valur TTL għar-rekord DNS li qed jiġi rritornat (jew il-valur minimu jekk sett minnhom ikun qed jiġi rritornat).
Abbażi ta 'hawn fuq, il-funzjonament ta' server DoH jikkonsisti f'diversi stadji.
- Irċievi talba HTTP. Jekk dan huwa GET imbagħad jiddekodifika l-pakkett mill-kodifikazzjoni base64URL.
- Ibgħat dan il-pakkett lis-server DNS.
- Ikseb tweġiba mis-server DNS
- Sib il-valur TTL minimu fir-rekords riċevuti.
- Irritorna tweġiba lill-klijent permezz HTTP.
3. Is-server DNS-over-HTTPS tiegħek stess
L-aktar mod sempliċi, veloċi u effettiv biex tħaddem is-server tiegħek DNS-over-HTTPS huwa li tuża web server HTTP/2 , li dwarha l-awtur diġà kiteb fil-qosor (ara “").
Din l-għażla hija sostnuta mill-fatt li l-kodiċi kollu tas-server DoH tiegħek jista’ jiġi implimentat bis-sħiħ bl-użu tal-interpretu integrat fl-H2O innifsu. . Minbarra l-libreriji standard, biex tiskambja dejta mas-server DNS, għandek bżonn il-librerija tas-Socket (mrbgem), li, fortunatament, diġà hija inkluża fil-verżjoni ta 'żvilupp attwali ta' H2O 2.3.0-beta2 fil-portijiet FreeBSD. Madankollu, mhuwiex diffiċli li żżidha ma 'kwalunkwe verżjoni preċedenti billi tikklona r-repożitorju għall-katalgu /deps qabel il-kumpilazzjoni.
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
...Il-konfigurazzjoni tas-server tal-web hija ġeneralment standard.
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.rbL-unika eċċezzjoni hija l-immaniġġjar tal-URL /dns-query li għalih is-server DNS-over-HTTPS tagħna, miktub b'mruby u msejjaħ permezz tal-għażla tal-handler, huwa fil-fatt responsabbli 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
}Jekk jogħġbok innota li s-server lokali tal-caching huwa responsabbli għall-ipproċessar tal-pakketti DNS, f'dan il-każ mid-distribuzzjoni standard FreeBSD. Mil-lat tas-sigurtà, din hija l-aħjar soluzzjoni. Madankollu, xejn ma jipprevjenik milli tissostitwixxi localhost għal indirizz DNS differenti li biħsiebek tuża.
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 *:*Li jibqa 'huwa li terġa' tibda l-H2O u tara x'jiġri minnha.
root@beta:/usr/local/etc/h2o # service h2o restart
Stopping h2o.
Waiting for PIDS: 69871.
Starting h2o.
start_server (pid:70532) starting now...4. Ittestjar
Allura, ejja niċċekkjaw ir-riżultati billi terġa 'tibgħat talba tat-test u tħares lejn it-traffiku tan-netwerk billi tuża l-utilità 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 kernelL-output juri kif it-talba biex tissolva l-indirizz example.com ġie riċevut u pproċessat b'suċċess mis-server DNS.
Issa dak kollu li jibqa' huwa li tattiva s-server tagħna fil-browser Firefox. Biex tagħmel dan, għandek bżonn tibdel diversi settings fuq il-paġni tal-konfigurazzjoni dwar: konfigurazzjoni.
L-ewwelnett, dan huwa l-indirizz tal-API tagħna li fih il-browser jitlob informazzjoni DNS network.trr.uri. Huwa rakkomandat ukoll li tispeċifika l-IP tad-dominju minn dan il-URL għal riżoluzzjoni tal-IP sigura billi tuża l-browser innifsu mingħajr ma taċċessa d-DNS f' network.trr.bootstrapAddress. U finalment, il-parametru innifsu network.trr.mode inkluż l-użu tad-DoH. L-issettjar tal-valur għal "3" se jġiegħel lill-browser juża esklussivament DNS-over-HTTPS għar-riżoluzzjoni tal-isem, filwaqt li l-aktar affidabbli u sigur "2" se jagħti prijorità lil DoH, u jħalli l-lokup standard tad-DNS bħala għażla ta' riżerva.
5. QLIGĦ!
L-artiklu kien ta’ għajnuna? Imbagħad jekk jogħġbok tibżax u sapportja bil-flus permezz tal-formola tad-donazzjoni (hawn taħt).
Sors: www.habr.com