linux

linux

Tag Description

  • Linux

    Articles related to the Linux operating system platform.

  • Healthcare

    The final frontier in technology.

  • Networking

    I.T. networking is a HUGE topic, and I am by no means going to cover every concept, tool, and scenario. What you will find here is a series of mini-guides designed to help you gain a basic

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  • Linux ACL File Systems

    Virtually any file system you apply to a Linux operating system (such as Ubuntu) will have ACL capabilities. ACL is an acronym for "Access Control List." In simple terms, it means the file system

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  • Gateways

    Routers manage routes. Some routers act as gateways. A gateway is a forwarding router that forms a bridge between local and remote networks. A gateway is required when sending a packet

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  • Netmask Filtering Deep Dive

    What is a Netmask (or Genmask)? And why is understanding it so important when it comes to network routing?

  • Split Gateway Tutorial

    Thinking of creating split routes or split gateways? This article is a basic introduction, but it is a hands-on tutorial and will walk you through the building blocks of

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  • Linux Networking F.A.Q.

    What is the purpose of routing tables?

    Routing tables inform the Linux kernel where to find destinations on a network. They describe information such as which network interface to send

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  • Linux Network Routing Best Practices

    Here are some brief concepts to keep in mind when adding new routes and routing tables.

    Master Routing Table Best Practices

    High level concepts to keep in mind when adding new

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  • Introduction to Split Gateways

    Having explained the process behind gateway routes in the previous article, what is a split

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  • Netmask/Genmask Conversion Table

    It's much easier for most people to reference charts of netmask/genmask/CIDR values vs. trying to remember them (though some common masks such as 0 and 255 are easy

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  • Linux Routing Table Architecture

    placeholder for routing table architecture discussion
  • iptables Commands

    There are a large number of filters you may apply to your server's network rules via the iptables command. Some of these are found in extensions to iptables.

    The following

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  • Virtual Private Networks (VPNs)

    This category contains articles about Virtual Private Networks (VPNs), such as what they are, why you may or may not need or want one, how they function, and how to pick the best VPN service

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  • Helpful Tips (iptables)

    Here are a few helpful tips related to rule and route testing.

    Don't Forget to Flush!

    If you make changes to ip rules, ip routes, or iptables and wish to utilize them prior to

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  • SystemD

    SystemD is a system manager. Also known as an initialization system, or a sort of system manager of systems, if you will.

    With regards to Ubuntu - which I am most

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  • Bibliography for VPN Articles

    This is a list of sources I found useful while writing my comprehensive guides on VPNs for Small Business Owners, Home Office Workers, and Split VPNs

    Bibliography for VPN

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  • Is Your VPN Helping or Hurting You?

    If you could sum up the purpose of a Virtual Private Network (VPN) in one word, what would it be? My choice: Integrity.

    Of course, I'm talking about data integrity. But, what

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  • iptables Protocols

    Protocols operate in a similar manner to Match Extensions. Protocols filter the current packet based on the current communications protocol. There are only a few options, and

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  • OpenVPN Version List and Changelog

    Table comparing the complete list of all OpenVPN versions. See below for pertinent notes.

    Clear as Mud: OpenSSL and Ubuntu's Versioning System

    I wrote a separate article on versioning errors in Ubuntu (False Version Reporting in Ubuntu 16.04) and used

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  • Testing Your iptables Rules

    It may not be obvious, but you need to test your rules - both routing rules (per ip rules) and iptables rules - before you cement them in place. One of the great things about the

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  • Ubuntu

    My Ubuntu Obsession

    In the Linux world, I'm most familiar with Ubuntu, which is why you'll find most code examples on my site are based on that platform. Much like Red

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  • Security Implications of Samba Access to non-ACL File Systems

    Several processes control the flow of data through a Samba-managed network connection. Ironically, the most important of them has nothing to do with networking.

  • Routing and Filtering Network Traffic

    A brief, high-level introduction to Linux networking architecture. Explains how the Linux kernel manipulates network traffic using a top-down approach and basic framework to route

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  • Route and Netstat

    This section describes the use of alternative tools to the iproute2 suite for viewing the status of a network. They may be old, but route and netstat can still be useful

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  • Follow the (ip) Rules

    Hopefully, you have already read and/or understand these concepts:

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  • iptables and iprules

    Primarily covers iptables, ipchains, and ip rules. It also touches on ufw (Uncomplicated FireWall), and nftables ("NetFilter Tables"), the successor

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  • Chart: iptables Command Matrix

    Chart of the most commonly used iptables rule syntax, demonstrating command syntax along with the tables and chains where each command may be utilized. The table scrolls

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  • OpenVPN and OpenSSL: Partners in Security

    This article examines the relationship between OpenVPN and OpenSSL, why the former depends on the latter, and why it's important to remain cognizant of software version numbers

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  • 5 Ways to Install OpenVPN on Ubuntu 14.04, 16.04, 18.04

    OpenVPN is an open source Virtual Private Network (VPN) software solution that rivals similar commercially available products. It allows you to use PKI (Public Key Infrastructure) and SSL/TLS

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  • False Version Reporting in Ubuntu 16.04

    Incorrect software versioning in official packages causes consternation and confusion for system administrators when installing or updating dependencies via package managers. This article seeks

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  • Bibliography (Networking Articles)

    Andreasson, Oskar. Iptables Tutorial 1.2.1. Chapter 6: Traversing of tables and chains. https://www.frozentux.net/iptables-tutorial/chunkyhtml/c962.html.

    Andreasson, Oskar. 2006.

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  • A Brief History of Linux Networking

    Have you ever wondered why Linux network management is so confusing? You need only make a cursory review of the history of Linux networking tools to understand how it got this way.

  • Linux Firewall Management Tools Overview

    Two systems built-in to Ubuntu manage network routing: route (a legacy system) and ip route. Both use the same underlying code, yet report networking context a

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  • Routes, Rules, and Tables

    This category primarily covers:

    1. iptables, iproute, and netfilter
    2. Routing network traffic
    3. How Linux structures network
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  • Special Routing Use-Case Scenarios (iproute2)

    Now that you have a basic understanding of Linux network routing, it's time to delve into some interesting things you can do with this information.

    Dropping Packets

    Here are

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  • iproute and Routing Tables

    We will begin the detailed discussion of the first component of the Routing Policy DataBase (RPDB) triad: routes (the other two components are ip rules and ip

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  • Policy Based Routing

    A traditional router stores network route information in routing tables. A routing table is a map of a network. Linux uses a policy based routing system, aptly called a

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  • Persistence: Making iptables Changes Stick

    One of the challenges of iptables, routes, and rules (iprules) is making changes to them permanent. Any changes you make on-the-fly only last until the next system restart.

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  • SECMARK Without SELinux

    Yes... it is possible

    This is not common knowledge. Contrary to most literature, you can use SECMARK and CONNSECMARK without SELinux. This article explains what that means and

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  • Help! I Can't Log into my Ubuntu Server!

    Can't boot your Ubuntu server?

    Garbled GRUB file got you down?

    SSH on the fritz?

    Driving you crazy and ready to DELETE AND REINSTALL the O.S.???

    Quick

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  • What is BaSH?

    Often written as "Bash" or "BASH"), BaSH is an acronym for "Bourne Again SHell." BaSH is a UNIX shell programming language interpreter that comes preinstalled with many UNIX and Linux

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