A certificate authority (CA) is who issues the digital certificates. We need this for installation of some software, such as OpenVPN. For doing that, we have to download the latest version of EasyRSA. EasyRSA is the CLI utility to build and manage a PKI CA. A CA acts as a trusted 3rd party. The format of these certificates is specified by the X.509 standard. A certificate signed by a … [Read more...]
Theory for Running OpenVPN on Server
OpenVPN is a free software for building a Virtual Private Network (VPN) via an encrypted TLS connection. For encryption OpenSSL or mbed TLS can be used. OpenVPN uses either UDP or TCP for transport. OpenVPN is under the GNU GPL and supports the Linux operating systems, Solaris, BSD, MacOS, QNX, Windows, Android, iOS. Also, there are customized implementations for a variety of Linux-based … [Read more...]
What is Asymmetric Cryptography?
Asymmetric cryptography or two-key cryptography is the cryptographic method that a pair uses of keys for sending messages. The two keys belong to the same person who will receive the message. One key is public and can be delivered to anyone, the other key is private and the owner must keep it so that no one has access to it. In addition, cryptographic methods guarantee that this key pair can only … [Read more...]
Use of Bitcoins in Online Trading : Part III
This is the third and final part of the series Bitcoins in Online Trading. The second part of the article can be read here. Through the Internet and its commercial use, the demands on cryptography have increased. Due to these requirements, a separate area has developed whose main task is new information systems that protect against unauthorized access. The aim of these crypto methods is to … [Read more...]
Apache Cassandra Versus Apache Phoenix
In our previous discussions, we have compared Apache Cassandra with Apache Hbase and Apache Cassandra with MongoDB. In one of those articles, we already mentioned that Apache Cassandra is more appropriate to compare with Apache Phoenix than Apache HBase. Also, it will make understand why commonly HBase is compared with Apache Cassandra, not Apache Phoenix. Apache Phoenix is a relational … [Read more...]
Use of Bitcoins in Online Trading : Part II
This is the second part of the series of articles on Bitcoins in Online Trading. The first part can be read from here. To better understand use of Bitcoin in online commerce, we first have to understand the online trade as a business concept. The term e-commerce consists of the two terms electronic and commerce. Thus, an online trade is understood as a business concept by generating the sales … [Read more...]
Use of Bitcoins in Online Trading : Part I
Money plays a central role as a recognized means of exchange and payment. Printed money is losing importance and money in digital form is becoming increasingly important. It is quite possible that the electronic money stored in the form of smart cards or in computer programs that can replace traditional coins and bills from the system. But not only the money in paper or coin form gets through the … [Read more...]
Apache Cassandra vs Apache HBase
In the last article we have compared Cassandra with MongoDB. That comparison made it obvious that we need to compare Cassandra with HBase, and MongoDB with HBase to complete the understanding. Cassandra and HBase are similar at many things but Cassandra's consistency model is like DynamoDB to provide eventual consistency. HBase is a part of HDFS which runs on top of Hadoop (based on … [Read more...]
MongoDB vs Cassandra : Comparison of NoSQL Databases
Previously we compared DynamoDB and MongoDB. MongoDB vs Cassandra is another frequently compared NoSQL database. Apache Cassandra is fully Free and Open Source Software which provides scalability. MongoDB is developed by MongoDB Inc, it has other options than just the MongoDB Open Source Software we commonly use. Apache Cassandra has scalability, linear performance, distributed architecture, … [Read more...]
WordPress Admin Post List Marker (Like email Inbox)
We have talked about the need to mark some articles with a star or some label to classify some posts at WordPress backend. Oddly, this function which is widely used in an email inbox is absent in WordPress admin post list. If you have some sponsored posts or posts with affiliate links, you can not easily find them among thousands of published articles. Admin tables are created using the … [Read more...]
What’s the Difference Between Hadoop and Spark?
Both Apache Hadoop and Apache Spark are big-data frameworks, but they do not serve the same purposes. Actually there are multiple big data frameworks on the market, Apache and Hadoop and Apache Spark are most known among them. They are commonly used to train the starters. But in real life, choosing the right big data framework is a challenge. Businesses consider each of the framework for their … [Read more...]