Category: Программирование

Setup DDNS/DynDNS in OpenWrt

I serving my small homepage directly from my router with OpenWrt Linux — thus I don’t have to pay for any hosting because the router is anyway always online. My provider gives to my router some public IP which is changes sometimes: maybe about once per week. That is fine for me but I have to change it manually. Of course I can buy a static public IP from my internet provider but my goal is to have cheapest as possible website. So I need to automatically and periodically update the DNS A record with my current IP. To solve this problem people uses Dynamic DNS (DDNS) which is de facto some pseudo protocol when router itself constantly registers it’s current IP on the DNS server. Most routers already have support of some DDNS providers where most popular are and or even manufactures like ASUS may have their own DDNS. Gamers and owners of IP cameras very often using this. Unfortunately my DNS registrar doesn’t support DDNS protocol so I have to use some another. A good news is that OpenWrt already have a package ddns-scripts witch supports a lot of servers. I checked almost all DDNS providers that are supported my and choose looks like one of the first DDNS providers and some other even tries to implement it’s API. But it’s paid and that’s not acceptable for me to because with the same money I just can buy a static IP. have some strange API problems with refreshing IP so there is even a separate script for OpenWrt `ddns-scripts_no-ip_com`. In the same time DuckDNS looks like was made by programmers for programmers. It allows to quickly register with Google account then they give you a generated random token instead of password and they have a good documentation. So the API is so simple that I even was wondered why it was created the ddns-scripts package. In fact, all what you need to do is to login to your OpenWrt LUCI admin panel, then open System / Scheduled Tasks and add the following line: «` * */4 * * * wget -4 -q -O /dev/null{YOURDOMAIN}/{YOURTOKEN} «` i.e. each 4 hours you will send a HTTP get request to DuckDNS. Then you can check logs of cron task in syslogs: System / System Logs. For example for my domain «` Mon Apr 22 18:52:00 2019 crond[12903]: USER root pid 14005 cmd wget -4 -q -O /dev/null «` or you can do the same with command line: «` ssh root@ root@OpenWrt:~# crontab -e root@OpenWrt:~# /etc/init.d/cron enable root@OpenWrt:~# /etc/init.d/cron restart «` Here note that I enabled the cron service just to be sure. Then your router will be accessible with the new domain. For example for my domain «` $ dig ; DiG 9.11.5-P1-1ubuntu2-Ubuntu ;; global options: +cmd ;; Got answer: ;; ->>HEADER<>HEADER<<- opcode: QUERY, status: NOERROR, id: 41868 ;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 1 ;; OPT PSEUDOSECTION: ; EDNS: version: 0, flags:; udp: 4096 ;; QUESTION SECTION: ; IN A ;; ANSWER SECTION: 24 IN CNAME 24 IN A ;; Query time: 212 msec ;; SERVER: ;; WHEN: Mon Apr 22 23:55:45 EEST 2019 ;; MSG SIZE rcvd: 129 «` You can see that was firstly resolved to CNAME which then was resolved to IP


Nginx Plus Docker Image + lua-resty-openidc for OAuth termination

I need a Docker image with Nginx Plus and configured lua-resty-openidc to use Keycloak OAuth provider.
I made it based on this article Deploying NGINX and NGINX Plus with Docker but there was few additional non trivial steps so here is my result.
Create a folder with nginx plus repo keys (nginx-repo.crt and nginx-repo.key)
Then create a Dockerfile with the following content:

FROM ubuntu:artful

# Download certificate and key from the customer portal (
# and copy to the build context
COPY nginx-repo.crt /etc/ssl/nginx/
COPY nginx-repo.key /etc/ssl/nginx/

# Install NGINX Plus
RUN set -x \
  && apt-get update && apt-get upgrade -y \
  && apt-get install --no-install-recommends --no-install-suggests -y apt-transport-https ca-certificates \
  && apt-get install -y lsb-release wget \
  && wget && apt-key add nginx_signing.key \
  && wget -q -O /etc/apt/apt.conf.d/90nginx \
  && printf "deb `lsb_release -cs` nginx-plus\n" | tee /etc/apt/sources.list.d/nginx-plus.list \
  && apt-get update && apt-get install -y nginx-plus nginx-plus-module-lua nginx-plus-module-ndk luarocks libssl1.0-dev git

RUN set -x \
  && apt-get remove --purge --auto-remove -y \
  && rm -rf /var/lib/apt/lists/*

# Forward request logs to Docker log collector
RUN ln -sf /dev/stdout /var/log/nginx/access.log \
  && ln -sf /dev/stderr /var/log/nginx/error.log

RUN luarocks install lua-resty-openidc
RUN luarocks install lua-cjson
RUN luarocks install lua-resty-string
RUN luarocks install lua-resty-http
RUN luarocks install lua-resty-session
RUN luarocks install lua-resty-jwt



CMD ["nginx", "-g", "daemon off;"]

Here you can see that we installing not only nginx-plus but also nginx-plus-module-lua and nginx-plus-module-ndk modules which are needed to run lua-resty-openidc.
Since open lua-resty-openidc is distributed via luarocks package manager we need to install it too and then install all needed packages via luarocks. For lua-crypto dependency you need to install libssl1.0-dev package with OpenSSL headers and for some other package we needed git, don't ask me why, I have no idea.
FYI: openidc is installed into file /usr/local/share/lua/5.1/resty/openidc.lua

Then you need to build an image with

docker build --no-cache -t nginxplus .

If you have a Docker Registry inside your company you can publish the image there:

docker tag nginxplus your.docker.registry:5000/nginxplus
docker push your.docker.registry:5000/nginxplus

Not you have an image and you can run it. All you need is to mount you server config into /etc/nginx folder. Consider you have a docker-compose.yml file with the following content:

version: '3'
    image: your.docker.registry:5000/nginxplus
    container_name: gw-nginx
      - ~/gateway/etc/nginx/nginx.conf:/etc/nginx/nginx.conf
      - ~/gateway/etc/nginx/conf.d/:/etc/nginx/conf.d/
      - /etc/localtime:/etc/localtime
      - 80:80
    image: jboss/keycloak
    container_name: gw-keycloak
      - /etc/localtime:/etc/localtime
      - 8080:8080
      - KEYCLOAK_USER=root
      - KEYCLOAK_PASSWORD=changeMePlease

Now create a gateway folder:
mkdir ~/gateway
cd ~/gateway
And plase nginx.conf file into ~/gateway/etc/nginx/nginx.conf. The most important is to place this two lines:

http {
  resolver yourdnsip;
  lua_ssl_trusted_certificate /etc/ssl/certs/ca-certificates.crt;
  lua_ssl_verify_depth 5;

For some reason without this lines Lua scripts can’t resolve upstreams.

Create ~/gateway/etc/nginx/conf.d/default.conf file and configure it as descibed in restly-openidc documentation.
Finally you can run it with docker-compose up -d command.

[Linkset] Authorization termination: OAuth reverse proxy

UPDATE Today was released Nginx Plus with a new nginx-openid-connect module.

If you are looking for Authentication Server or OAuth library then OpenID Conect implementations page is a good place to start. I chose Keycloak but also want to look on FreeIPA or

Keycloak Security Proxy but I want proxy as Nginx module and I need to implement something non standard.
Also there is some an OpenID/Keycloak Proxy service

For Apache web server everything is clear:

But I need something for Nginx .

lua-resty-openidc and it’s intro blog post written in Lua so its easier to extend (so I did for implementing of custom grant flow+ sessions + reference tokens). written fully in C++ and this is interesting because you don’t need to enable Lua on Nginx (believe me, this can be harmful).

What is also interesting is tha module for only one purpose: to use reference tokens (opaque tokens) it’s written in C so no needs for additional deps.

Authentication Based on Subrequest Result

Actually Nginx already has something that can satisfy 80% of your needs:

But to use the sebrequest auth your auth server should support this or you need to setup another shim proxy:
and here is docker container which integrates it

Or you can use this one which is written in Lua

Important article from Security researcher Egor Homakov who hacked several times GitHub and Facebook:

OAuth1, OAuth2, OAuth…?

Вебинар: Как защитить свой сайт от хакеров если вы ленивый

Всем привет и с праздниками.
Утром проснулся и подумал: «а что ты сделал для человечества?» и вспомнил что у меня есть презентация про то как быстро улучшить безопасность сайтов для таких ламеров каким я был три года назад когда начал вникать в тему.
И я бы хотел замутить небольшой вебинарчик и чтобы закрепить я выдам домашнее задание и тем кто его выполнит подгоню каких нибудь ништячков.
В двух словах:
0. Цель вебинара: дать совсем чуть-чуть самых базовых знаний о том как делать защиту сайта и научить практическим методам защиты при этом упор только на Quick Win приёмы которые можно быстро и ненапряжно внедрить и они закроют большую часть уязвимостей. Никоим образом после этого вебинара у вас не будет понимания того как защищаться, вы будете такими же дебилами в инфо секьюрити как и прежде, но хотя бы совсем лажать не будете. Т.е. советы будут уровня «мойте руки перед едой» но на практике 90% программистов с которыми я работал даже этого не знают потому что «некогда нам, нужно тикеты закрывать и бизнес вэлью делать ведь у нас Аджайл и вообще кому мы нафиг нужны».
1. Для кого: любой веб программист любого уровня на любом языке (но пару примеров будет на PHP). Если вы шарите в теме тем более приходите: дам микрофон, буду рад услышать ваши советы и замечания.
2. Необходимые знания: базовое понимание работы HTTP, опыт вёрстки сайтов минимум год
3. Агенда:
3.0 Покажу как проверить хакнули вас или нет. Ну чтобы запугать хорошенько.
3.1 Почему ваш сайт обязательно должен отдаваться через https, как получить сертификат на халяву через Let’s Encrypt
3.2 В основном я буду рассказывать про то что такое XSS и как защищаться от него с помощью Content Security Headers (CSP). Это очень простой но супер эффективных механизм.
3.3 Как защитить пароли пользователей и как их правильно захешировать (password shadow)
3.4 Возможно подраскужу ещё чего нибудь простенького но эффективного в качестве небольшого офтопа.
4. Когда: не раньше чем через пару месяцев утром в субботу. Я сейчас очень уставший, у меня много работы и ещё я недавно стал отцом и не высыпаюсь. Время буквально краду у семьи.
5. Дисклаймер: я не секьюрити специалист а всего лишь веб программист которому немного пришлось вникнуть в тему. Моя личная цель самому себе закрепить опыт и передать вам потому что я же блин сам вашим софтом и пользуюсь. Вы собственно всё сами можете почитать и изучить просто я вам время сэкономлю.
Короче будет норм, регайтесь друзья тут или следите за бложиком.

Don’t remove folders from your app, just clear all inner files

Dear programmers, if your application uses some folders please never delete the folders and just clear all inner files instead.
Because users may symlink any folder to another disk (e.g. RAM) or chmod them with different privileges.
For example, Maven always removes a target folder when calling mvn clean install and this creates a problem for me because I mapped the target folder to RAM disk.
This is not a rule to follow, but something that you may think about during development.


How to: LetsEncrypt HTTPS on OpenWRT with uhttpd

My old router TP Link WRN740N hosting my homepage and it’s too small to handle full LetsEncrypt certbot installer and OpenSSL. So if you want to enable HTTPS you have to run certbot on some other machine and then upload to router.
Here I would like to show how I did that.

Manual installation

The fisrt step is to use manual certs installation from my laptop and renew them after 3 month. Actually this can be automated too latter.

Now, lets generate certs for your domain:

$ sudo certbot certonly --manual --preferred-challenges http

Answer all the questions and it will ask you to upload a file to your router:

Create a file containing just this data:


And make it available on your web server at this URL:

Press Enter to Continue

You need to create the folder on router:

# mkdir -p ./.well-known/acme-challenge

Then upload the files via SCP from your computer to router:

$ echo "1Fyw2Q3IARaG0G6RVUJS587HG_Ou6pKpBLZC-_KeC4g.OKKBaAC2SgfXHQyvgKrLkn3zyCNH82xHgKsMg9OQQJE" > 1Fyw2Q3IARaG0G6RVUJS587HG_Ou6pKpBLZC-_KeC4g

$ scp ./1Fyw2Q3IARaG0G6RVUJS587HG_Ou6pKpBLZC-_KeC4g root@

BTW, there is no any analogue of WinSCP for Linux but you can try to run it on Wine.

Then go back to certbot and press Enter. It will check that files are in place and accessible from web.

 - Congratulations! Your certificate and chain have been saved at:
   Your key file has been saved at:
   Your cert will expire on 2018-01-13. To obtain a new or tweaked
   version of this certificate in the future, simply run certbot

It generated two files: privkey.pem and fullchain.pem (which is not public key!)

Finally, you need to convert the private key and the certificate from the ASCII-armored PEM format to the more economical binary DER format used by uhttpd:

openssl rsa -in privkey.pem -outform DER -out uhttpd.key
openssl x509 -in fullchain.pem -outform DER -out uhttpd.crt

Upload them to the router

$ scp uhttpd.crt root@
$ scp uhttpd.key root@

On the router you need to install uhttpd-mod-tls:

# opkg update
# opkg install uhttpd-mod-tls

edit /etc/config/uhttpd as described in docs i.e. like this

config uhttpd ''
    list listen_http ''
    list listen_https ''
    option redirect_https '1'
    option home '/www'
    option rfc1918_filter '0'
    option cert '/etc/uhttpd.crt'
    option key '/etc/uhttpd.key'

Here is my public static IP.
Note that 443 port should be opened in /etc/config/firewall:

config rule
    option target 'ACCEPT'
    option src 'wan'
    option proto 'tcp'
    option dest_port '443'
    option name 'HTTPS'

Then restart the firewall and uhttpd server:

# /etc/init.d/firewall restart
# /etc/init.d/uhttpd restart

Now try your site in browser. But please check your site latter: I noticed that uhttpd was down but after restart it worked well.

Renewing cert

… So it passed 3 months and my cert got expired and I need to renew it. It’s funny that today is an Old New Year and from window I hear some concert on my street.
This time I decided not to use manual mode and use standalone mode instead: certbot starts itself an https server on 443 port and I need to shut down webserver on my router and enable 443 port forwarding from router to my laptop.

So let’s do that:
1. Connect to router and stop uhttpd service:

$ ssh root@
# /etc/init.d/uhttpd stop
  1. Enable 443 port forwarding. Download firewall config from router:
$ scp root@ ./
  1. Edit and comment out current rule for 443 port. If you used that one that I mentioned before then:
# temporarry comment out the rule
#config rule
#  option target 'ACCEPT'
#  option src 'wan'
#  option proto 'tcp'
#  option dest_port '443'
#  option name 'HTTPS'

Then add a HTTPS forwarding rule:

config 'redirect'
    option 'name' 'HTTPS_to_laptop'
    option 'src' 'wan'
    option 'proto' 'tcp'
    option 'src_dport' '443'
    option 'dest_ip' ''
    option 'dest_port' '443'
    option 'target' 'DNAT'
    option 'dest' 'lan'

Where is the ip of the your laptop. Run ifconfig to see it.

  1. Upload the new firewall config to router:
$ scp ./firewall root@
  1. Now restart firewall service on router:
# /etc/init.d/firewall restart
  1. Now your laptop’s 443 port is exposed to the world. So lets tun certbot:
$ sudo certbot certonly --standalone --preferred-challenges tls-sni
  1. Then convert the keys do DER format and upload to router as was described above. Then disable forwardind firewall rule and rollback previous and restart firewall and uhttpd.

Now you certs was renewed.

Субботние лекции: Как перестать верить технологиям

Наверное уже все посмеялись что ещё не было дня чтобы не выпустили новый JavaScript фреймворк, но фронтендщикам уже не до смеха. У них сейчас происходит перидод бурного эволюционного развития и конца этому пока не видно.
На самом деле точно такие же процессы проходили и проходят прямо сейчас и в других областях но по стечению множества причин именно во front end этот процесс сейчас самый большой и бурный и дошёл до абсурда хотя фронтендеры говорят что это они просто к точке сингулярности приближаются, хех.

Как выжить этим отважным парням в таких условиях? Есть на эту тему триптих из трёх лекций.


Как ответ на неё последовала вторая:

там он ссылался на эту офтопную лекцию

И финальная третья лекция