TechnoExploration

Lets explore Linux, Networking, and technology together!

[technoexploration-blog]

The Command Line

Welcome back again, gentle readers!  Tonight we will continue with a lighter topic: the command line.  Truthfully we could fill a book (and others have!) of everything the command line is capable of.  The purpose of this entry is not to make you a command line expert, but to get you comfortable with some of the functions of the command line.  Most of these commands should work regardless of the linux distribution you’re running.  Where there are differences I will try to point them out.  As an aside: I know that everyone has a preference in terminals, whether it’s tilex, yakuake, or the standard terminal that comes bundled with your distro.  No judgements, but I do encourage you to explore different options to figure out what works best for you!

To start lets install a program:

For Ubuntu based distributions:

sudo apt-get install -y cowsay fortune

For RHEL/Fedora-based distributions:

sudo dnf install cowsay fortune

or for CentOS:

sudo yum install cowsay fortune

This command installs two programs.  Cowsay and Fortune.  I will go into more details regarding these programs later, however if you want to remove them at any point just replace “install” with “remove” in the commands above.

So, what can we do with the command line?  Short answer: just about everything!  Being comfortable in the command line requires a certain amount of imagination, and a little bit of intuition.  One of the most useful features of the command line, for me anyhow, is tabbing.  Try this command out:

ip 

instead of pressing ‘Enter’ press ‘Tab’ twice.

you should see a list of possible commands populate.  This is useful if you’re familiar with a program (such as ip) but don’t recall a specific command.

The next feature of the command line you should know is the double &.  This strings two commands together, which is useful in distributions like Ubuntu where you have to run two separate commands to update and upgrade.

sudo apt-get update && sudo apt-get dist-upgrade

does the same thing as:

sudo apt-get update

sudo apt-get dist-upgrade

In other distributions you’ll find it useful when conducting routine installations, for instance installing nginx:

sudo dnf install nginx && sudo nano /etc/nginx/nginx.conf

This string of commands will install Nginx (a webserver) and then open the configuration file in nano for editing.  Nano can be swapped out with your preferred text editor (vim, gedit, kate, etc...)

The last useful feature we will cover is the pipe ‘|’ otherwise known as “shift + \”.  The pipe takes information and allows it to be filtered or otherwise manipulated.  For instance run the following command:

fortune | cowsay

And now we come full circle.  This pipes the output of the program “Fortune” into the program “Cowsay” which outputs the text as a speech bubble coming from a cow.  I sometimes use ‘cowsay’ to parse logs...because even bad news sounds better when coming from a cow!

Other uses for the pipe include parsing output using grep.  Try this out:

cd /

sudo find | grep cowsay

Your output should show any files or folders that contain the word ‘cowsay’.

Now, if you were to say:

sudo find | grep fortune | cowsay

The output would be a search of all files that contain the word ‘fortune’ output in the speech bubble of a cow!  The formatting isn’t the best, but it’s a fun way to parse information, and you get to use a double pipe!  I know...I’m a nerd.

Next time we will explore something a little more exciting now that we’ve gotten the basics out of the way.  Until then, continue exploring!

~TechnoExplorer

[technoexploration-blog]

Firewalls

Thank you for joining us!  I hope you had a wonderful turkey day, complete with too much food, and not enough time to eat it all!

Today, I want to discuss Firewalls!  Certainly not the most exciting topic, unless you’re me, but something everyone should have at least a lateral understanding of if for no other reason than to stay safe online and understand what all of those popups in windows really mean!

The Basics:  So, what is a firewall?  Well, in the simplest terms it can be thought of as a bouncer for your network that sits in front of all of the ports.  If a connection isn’t on the list it isn’t allowed into your network.  For example, if someone sends you data over port 331 but it’s not on your firewalls list it will be rejected.  As irritating as it is, and for all of the guides online that recommend disabling the firewall it really is a good thing, and with just a few commands and a little reading the firewall can be configured to do your bidding!

TLDR: Firewalls are good, they block traffic that you don’t explicitly allow onto your network.

A little more info:  So, how do we interact with the firewall?  How does it know what to do?  This is where most operating systems fall a little flat, and although Microsoft and Apple do try, the information isn’t really in plain english that the end-user would understand.  We have been well trained to click through whatever pops up and let Windows just do it’s thing.  Although convenient, it’s not ideal.  Linux does a little less hand-holding, but is still guilty of being a little archaic by burying the reasons for firewall issues in system logs where most people wouldn’t know where to look.  Thankfully in many distributions the firewall is pre-configured to allow traffic across port 80 so at least you can search google for the answer!  If you’re working in an Ubuntu-based distribution, you have an option called UFW that allows you to pass commands to the IP tables in the following format:

user@localhost user$: sudo ufw enable

Please enter the password for user:

So, lets parse the above commands:  Sudo allows you to execute a command as administrator.  UFW is the name of the program we are trying to execute the command on, and enable is telling UFW to start when the OS starts.

ufw enabled

This shows us that UFW is enabled, and will start when the system starts.

user@localhost user$:sudo ufw allow tcp/22

this command tells UFW to allow traffic on TCP port 22, alternatively you could specify UDP or both for TCP & UDP.  Port 22 is traditionally the port used for SSH and SFTP.

rules updated IPv4 rules updated IPv6

The output from the command above should resemble this.  This simply informs you that the command was successful and that the rules have been updated.

user@localhost user$: sudo ufw reload

This command reloads the rules in the firewall so that they become active.

Red Hat (and Fedora/CentOS by extension) use firewalld as a default firewall.  The commands run similarly, however it is worth noting that they all also use “systemctl”, so to enable the firewall in these distributions you would enter:

centos@localhost centos$: sudo systemctl enable firewalld

and to reload the rules you would type:

centos@localhost centos$: sudo systemctl restart firewalld

I hope this was insightful.  I know that working with firewalls for many people (especially if you’re working from an unfamiliar command line) can be frustrating, but please remember to keep at it, and although it takes time, once you have it figured out you’ll hardly notice it at all!  A properly configured firewall is one that only gives you trouble when something isn’t right!

TLDR:  Most operating systems come with at least a basic firewall, and from a security standpoint it’s worth getting to know them, and knowing your network to understand why specific ports are open.  Leaving a port open for no reason is like locking your doors, but leaving all of your windows wide open!

Until next time, keep exploring!

~Technoexplorer

[technoexploration-blog]

Linux, Part 2

Good afternoon, gentle readers! Today I will wrap up my discussion of Linux. See, wasn't that quick and painless? Today will simply be a quick rundown of some of the tools that I use in Linux to communicate and manipulate my network environment. As always, go with what you know! I will include Windows alternatives as I am aware of them. MacOS users, please feel free to chime in with Mac alternatives if you know of them too!

SSH: This is one of the first things I set up. This allows me remote access to my server. Even though it's across the room, I'm lazy and don't like constantly getting up and down to configure stuff. You can install this on most Linux distros by installing open-ssh or searching for it on your graphical package manager.

Once you've gotten ssh installed and configured to your liking you can connect remotely to your server by opening a terminal window and typing:

ssh [user]@[IP address or domain name]

Enter your credentials when prompted and you're in!

For Windows PCs WinSCP should provide similar functionality and with the correct credentials you should see the terminal on your server!

Minicom: this program is what's called a terminal emulator. It is useful for connecting to switches with a COM link or null modem. We'll come back and explore this another time in more detail! A Windows alternatives would be RealTerm.

VirtualBox: This software is widely available on most platforms. This can be run locally or remotely on your server in "headless" mode. I primarily use this to test features and programs to ensure compatibility before doing a live install, and to extend functionality of my server.

PFSense: This is an operating system that functions as a UTM (Unified Threat Management) system. This sits on the edge of my network between my router, switches, and my modem. Some have said they see increased throughput running PFSense, however I'm running it for the additional level of control and monitoring that it provides -- any additional throughput is a bonus.

Yakuake: This is more preference than convenience but Yakuake is a drop-down terminal (quake-style).  I prefer this style terminal because with a press of a key I can call and then hide the terminal window, this is useful when I’m making changes to programs or inputting commands from another website.

Qreator: This is a nifty program that allows you to create custom QR codes.  Not sure that we’ll ever cover this in great detail, but a useful tool all the same.

GIMP: Stands for the Gnu Image Manipulation Program, this is an open source alternative to Photoshop, but be forewarned it is not Photoshop.  Don’t make the mistake and assume that it will work exactly the same.  This is a great program capable of light image editing.  Again, probably beyond the scope of this blog, but who knows?

Thank you for tagging along!  Next time we will cover something much more interesting, I promise!  In the mean time, explore on!

~TechnoExploration

[technoexploration-blog]

Linux...the other OS

Good evening gentle readers!  Welcome to my second post.  As promised, lets talk about Linux!  I know...you’re thinking “Another blog about Linux...great!”.  Stay with me though, I promise we’ll quickly move through Linux over the next couple of posts and then it will be on to the fun stuff, like Firewalls, UTM’s, routers, and switches!

I want to preface all of this by saying - I am not an expert in any of these topics, I do however know what works for me.  I know that what works for me doesn’t work for everyone, and I’m always open to different opinions.  At the end of the day you should go with what works for you, not what works for the first page of your google results.

Now, with the formalities out of the way, there are a couple of terms that you should be aware of:

Distribution:  This is the base Operating System.  Whether it’s Ubuntu, Debian, Fedora, Red Hat, CentOS, Windows, or MacOS this is the operating system.  The operating system will dictate what kinds of files you can run (.exe, .deb, .rpm, etc.) and how you manage your system resources.

Desktop Environment:  This is where Linux gives you freedom.  The desktop environment (or DE) is what draws those pretty pictures on the screen (docks, buttons, icons, cursors, etc).  Some options in Linux include GNOME, KDE, Cinnamon, MATE, and XFCE, there are more but these are examples of the more common ones you’ll see.  For Windows and MacOS users this can be thought of in terms of the differences between OS versions, such as Windows XP and Windows 10.  The functionality is there but the layout is different.  Sometimes the learning curve is a little steeper than others (I’m looking at you Windows 8!)

So, what does it all mean?  Well, the first thing that most Linux users cite is the freedom.  For me that means I can mix & match distributions (distros) and DE’s almost entirely at will!  I could use Ubuntu with KDE or Gnome just as I could use CentOS with Cinnamon if I chose.  This gives users a great deal of freedom, but it also provides some consistency -- whether I’m using Fedora, Ubuntu, CentOS, or ArchLinux I could conceivably use Cinnamon across all four and have at least some level of familiarity with the OS.  

Once you hit the command-line is where you’ll begin to see differences.  Each Distro uses it’s own unique package manager: Ubuntu uses “apt”, while Fedora uses “dnf”, CentOS uses “yum”, and ArchLinux uses “pacman” (short for PACkage MANager).  At the end of the day though they all provide the same functionality -- find and install packages.  Being familiar with the command line used to be a requirement, however now (with the exception of ArchLinux, though it’s been quite a few years) it’s not as much of a requirement.  Most distributions come with a graphical package manager, and for those few occasions where you need to go into the command line there are excellent step-by-step guides available online.

For those who are still hesitant (or curious) most distributions have a live-cd that you can download and experiment with the OS before wiping out all of your files.  Another alternative is to grab a virtual machine player (such as VirtualBox), download the .iso from the site and install the OS on the virtual machine -- if you don’t like it you can simply delete it!

For the purposes of most of my experimentation I have four OS’s that I will be using: Windows 10, KDE Neon, Ubuntu Server (via SSH), and CentOS (with KDE).  I encourage everyone to experiment a bit, however at the end of the day you need to go with what you know, and there’s no shame in that!

Until next time fellow explorers,

~TechnoExploration

[technoexploration-blog]

My first post!

Welcome to my corner of the interwebz!  I will use this small corner to discuss my adventures in Linux, Networking, PC’s, Scripting, and honestly just about anything else that catches my interest.  Stay tuned!  

I’m anticipating my first post to involve a brief discussion of various distributions, desktop environments, and what I consider when selecting what I will install on my machines!  I’ll also use that post to explore the different options that tumblr has to offer!  I’m not sure if there’s commenting available yet, but if there’s a specific topic you’d like me to cover (and it also catches my interest) be sure to leave a note!