Fediverse refers to a network of federated, independent social networks, microblogging services and websites for online publication or data hosting. The concept emerged in 2008 with StatusNet on Identi.ca and from 2012 with GNU Social, and in 2016 it became increasingly widespread with Mastodon and the ActivityPub communication protocol defined by the World Wide Web Consortium (W3C) in 2018. … [Read more...]
How to Add a SSH Pre-Login Message in Ubuntu 22.04
An SSH Pre-login message can deliver a legal warning to unauthorized users. If the response after typing root@ip.address displays only the password: field, then an attacker's advocate in the court may argue that we have not warned his/her innocent client. Of course, you must enable a Passwordless SSH Login method whenever possible, even add a Bastion host for login purpose. But, we can not use … [Read more...]
Basics of Mail Server and Mail Transfer Agent (MTA)
In contrast to telephone or Internet relay chat, which enable simultaneous (synchronous) communication, e-mail – like letter mail – is an asynchronous communication medium: the sender sends his message regardless of whether the recipient can receive it immediately or not. A mail server is a server that can receive, forward, hold, and send emails. The e-mail addresses whose e-mail mailboxes are … [Read more...]
Basics of Configuration File
A configuration file is a file on a computer that stores certain settings (the configuration) of computer programs or hardware components. The use of simple text files in the usual encoding on the respective operating system, such as ASCII or UTF-8, is widespread, so that they can be edited with a wide variety of programs, e.g. any text editor or on the command line. Configuration files can also … [Read more...]
Set Up Email with mSMTP on Ubuntu 22.04 Server
This is a sendmail emulator system which delivers email from a local computer to an SMTP server. This method avoids the usage of cloud-based transactional email subscriptions. This is useful if you already using a paid tier of Outlook Gmail or Zoho for your domain. In other words, you'll get domain-branded, whitelisted email from your server to your mailbox. Normally we need server cron and … [Read more...]
How to Optimize Apache Keepalive Settings (Ubuntu Server + WordPress)
In our earlier articles, we have discussed How to Install Apache and PHP on Ubuntu 22.04 Server and What is Keepalive in the Context of Apache Webserver. From the previous articles, we have learned that: Keepalive is a mechanism in data transmission with the goals of maintaining a network connection and convincing oneself of the accessibility and function of a communication partner. Keepalives … [Read more...]
What is Keepalive (in the Context of Apache Webserver)
Keepalive is a mechanism in data transmission with the goals of maintaining a network connection and convincing oneself of the accessibility and function of a communication partner. Keepalives are usually specific packets of a network protocol. A keep-alive signal is often sent at predefined intervals. If no response is received after a signal is sent, it is assumed that the connection is lost, or … [Read more...]
What is Data Packet
In data processing, a data packet is a compilation of related digital data, precisely defined by the communication protocol, which is sent through a data network during data transmission. This packet transmission is common in all forms of the Internet and is the basis for the functioning of the networks. Internet data packets have a 24-byte header. A data packet has a prescribed number of bits. … [Read more...]
How Stateful Packet Inspection Works
Stateful Packet Inspection is a dynamic packet filtering technique in which each data packet is assigned to a specific active session. The data packets are analyzed and the connection status is included in the decision. In this technique, which is used in firewalls, the data packets are analyzed during transmission on the switching layer (3rd layer of the OSI model) and stored in dynamic state … [Read more...]
How Packet Filter Works (iptables)
A packet filter, also known as a network filter, is an application or software that filters incoming and outgoing traffic on a computer network. This is usually to protect the network from attackers. Just as important as protection against external attackers is protection against unintentionally outgoing packets; This can make it more difficult, for example, for one's own computer to spread … [Read more...]
General Basics of Firewall
A firewall is a security system that protects a computer network or an individual computer from unwanted network access. More broadly, a firewall is also a sub-aspect of a security concept. Every firewall security system is based on a software component. Firewall software is designed to restrict network access based on the sender or destination and services used. It monitors the traffic passing … [Read more...]