Articles related to the Linux operating system platform.
The final frontier in technology.
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
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
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
What is a Netmask (or Genmask)? And why is understanding it so important when it comes to network routing?
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
Routing tables inform the Linux kernel where to find destinations on a network. They describe information such as which network interface to send
Here are some brief concepts to keep in mind when adding new routes and routing tables.
High level concepts to keep in mind when adding new
Having explained the process behind gateway routes in the previous article, what is a split
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
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.
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
Here are a few helpful tips related to rule and route testing.
If you make changes to ip rules, ip routes, or iptables and wish to utilize them prior to
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
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
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
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
Table comparing the complete list of all OpenVPN versions. See below for pertinent notes.
I wrote a separate article on versioning errors in Ubuntu (False Version Reporting in Ubuntu 16.04) and used
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
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
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.
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
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
Hopefully, you have already read and/or understand these concepts:
Primarily covers iptables, ipchains, and ip rules. It also touches on ufw (Uncomplicated FireWall), and nftables ("NetFilter Tables"), the successor
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
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
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
Incorrect software versioning in official packages causes consternation and confusion for system administrators when installing or updating dependencies via package managers. This article seeks
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.
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.
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
This category primarily covers:
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.
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
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
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.
This is not common knowledge. Contrary to most literature, you can use SECMARK and CONNSECMARK without SELinux. This article explains what that means and
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.???
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