Category: Linux

Link: How To Configure Port Knocking Using Only IPTables on an Ubuntu VPS

Servers that are connected to the internet are subjected to all manners of attacks and probes by malicious users, scripts, and automated bots. It is sometimes a balancing act to secure your server from attacks without affecting legitimate access to your services and resources.

Certain types of services are meant to be visible and consumable to the public internet. An example of this is a web server. Other types of services are typically used by only the system administrator or a select number of individuals and are not meant to be a public resource.

A concept known as port knocking is a way of shielding processes that fit into the latter description. Port knocking works by covering the ports associated with a process behind a firewall until a specific, predetermined sequence of network activity occurs. At this point, the port knocking service reconfigures the firewall to allow access to the protected application.

Full article here:
How To Configure Port Knocking Using Only IPTables on an Ubuntu VPS (DigitalOcean)
Related:
How To Use Port Knocking to Hide your SSH Daemon from Attackers on Ubuntu (DigitalOcean)

Link: 29 Practical Examples of Nmap Commands for Linux System/Network Administrators

The Nmap aka Network Mapper is an open source and a very versatile tool for Linux system/network administrators. Nmap is used for exploring networks, perform security scans, network audit and finding open ports on remote machine. It scans for Live hosts, Operating systems, packet filters and open ports running on remote hosts.

Full article here:
29 Practical Examples of Nmap Commands for Linux System/Network Administrators (Tecmint)

Related articles:
Beginner’s Guide to Using nmap (Make Tech Easier)
Advanced Uses For Nmap (Make Tech Easier)

Link: How to Use Btrfs On Newly Installed Disks (+ additional Btrfs links)

Btrfs (pronounced ‘Butter F S’) is an advanced filesystem for Linux which can work across multiple hard disks and supports different fault tolerance models like RAID 0, RAID 1 and RAID 10. Btrfs has been in development since 2008 and it is what is known as a “copy on write” filesystem which means that when the data changes in a block, then the block will be copied a new block written to the disk with the changes incorporated. This means that blocks are never modified but rather new blocks are created and the old blocks are later reused. This has advantages for performance especially when ensuring consistency and integrity (even after a power interruption).

Full article here:
How to Use Btrfs On Newly Installed Disks (Make Tech Easier)

Related articles from ZDNet:
Btrfs hands on: My first experiments with a new Linux file system
Btrfs hands on: An extremely cool file system
Btrfs hands on: Exploring RAID and redundancy
Btrfs: Exploring its powerful filesystem subvolumes and snapshots
Btrfs hands-on: Exploring the error recovery features of the new Linux file system

Link: 20 Linux YUM (Yellowdog Updater, Modified) Commands for Package Management

In this article, we will learn how to install, update, remove, find packages, manage packages and repositories on Linux systems using YUM (Yellowdog Updater Modified) tool developed by RedHat. The example commands shown in this article are practically tested on our CentOS 6.3 server, you can use these material for study purpose, certifications or just to explore ways to install new packages and keep your system up-to-date. The basic requirement of this article is, you must have a basic understanding of commands and a working Linux operating system, where you can explore and practice all the commands listed below.

Full article here:
20 Linux YUM (Yellowdog Updater, Modified) Commands for Package Management (Tecmint)

Link: Linux: Keep An Eye On Your System With Glances Monitor

Is there is a tool that can provide me a maximum of information (such as cpu, disk I/O, network, nfsd, memory and more) about my Linux/Unix server in a minimum of space in a terminal?

…..

Say hello to Glances

From the project home page:

Glances is a free (LGPL) cross-platform curses-based monitoring tool which aims to present a maximum of information in a minimum of space, ideally to fit in a classical 80×24 terminal or higher to have additionnal information. Glances can adapt dynamically the displayed information depending on the terminal size. It can also work in a client/server mode for remote monitoring.

Full article here:
Linux: Keep An Eye On Your System With Glances Monitor (nixCraft)

Note that in addition to the above article, the project page for Glances can be found here.

Link: Manage Multiple SSH Connections Easily With PAC Manager [Linux]

If you have used SSH to connect to a remote machine before, you know the procedure: open a terminal, type in the SSH command and the host IP, enter the password. This is probably easy for a single connection, but if you are a system administrator looking after several remote machines and have a need to manage multiple SSH connections, you will need a better and easier solution. You need PAC Manager.

Full article here:
Manage Multiple SSH Connections Easily With PAC Manager [Linux] (Make Tech Easier)

Link: Midnight Commander Custom Interface Colors

Most Linux users are already familiar with the popular Midnight Commander console file manager so I will forego the introduction. This file manager supports custom user interface color schemes for increased personalization. The color scheme can be modified conveniently at any time by editing a single configuration file.

Full article here:
Midnight Commander Custom Interface Colors (Linux Library)

Link: Setting up VNC on Raspberry Pi

Although the Raspberry Pi can be connected to a TV or monitor via HDMI or DVI, there are times when running a Raspberry Pi “headless” (without a monitor) is desirable. In a headless setup, you could connect to your Raspberry via SSH but if you want the full desktop then you will need to connect using a remote desktop protocol. The easiest is to setup VNC on Raspberry Pi. Virtual Network Computing (VNC) is a graphical desktop protocol that allows you to access the full Raspberry Pi desktop from another machine. Typically you would run the VNC client on a PC running Windows, OS X or Linux and access the Pi’s desktop over the network.

Full article here:
Setting up VNC on Raspberry Pi (Make Tech Easier)

Related link:
VNC Starting Automatically on Raspberry Pi (School Pi Club)

Link: Record Audio from System/Microphone/Applications with ‘Audio Recorder’, Available for Ubuntu/Linux Mint

Audio Recorder is an amazing audio recording program, this small tool allows user to record audio from microphones, webcams, system sound card, media player or web browser & etc. It can save recording in various formats listed: Ogg, Mp3, Flac, Wav (22khz), Wav (44khz) and Spx.

Full article here:
Record Audio from System/Microphone/Applications with ‘Audio Recorder’, Available for Ubuntu/Linux Mint (Noobs Lab)