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Cornucopia of Ideas GNU/Linux, Networking, Security and more ...

Measuring a Temperature with DS18B20

DS18B20 is a digital temperature sensor which measures temperatures from -55°C to +125°C. It uses 1-Wire communication protocol. We have only one data pin for sending and receiving data. For more information see DS18B20 datasheet. In this post I will use Raspberry PI-III as a micro controller. For data pin I chose GPIO26. Before using this pin as a 1-Wire, we need to enable 1-Wire communication. You can do it raspi-config or adding the lines below end of the /boot/config.

Redirecting http to https

Do you have a SSL certificated web site and your audience still connects you via http because of their habit ? Easy way to handle this problem is redirecting http requests to https. By doing that any http requests are redirected to the https. To do that we will use Apache web server (httpd RHEL,CentOS). Apache is the world’s most used web server software. It has many features loadbalancing, cgi support, headers and content rewriting, URL rewriting etc,.

Port Knocking

Port Knocking Port knocking is one of hardening method to prevent unauthorized user access the services. This method ability to externally open ports that, by default, keep closed by firewall. It works by sending TCP packets to predefined closed ports in right order. In my virtual environment, I have two Linux based systems one is Debian8 and the other is Centos7. Debian8(Server): IP: 192.168.17.139 Services: knockd,ssh Centos7(client): IP: 192.168.17.135 Services: ssh

Free SSL Certificate

Q: Is is possible to get free SSL certificate, which is supported by modern web browsers such as Chrome, Mozilla Firefox, IE etc,. A: Actually, yes you can have free green bar SSL certificates which is supported by modern web browsers. Let’s Encrypt is a free, automated, open Certificate Authority. But before you have SSL certificate, It requires some of the things you have to do to confirm you are the owner of domain that you want to get SSL certificate.