Hello fellow Linux enthusiasts!
As many of you know, Linux can be a powerful and flexible operating system, but it can also be daunting for new users, especially when it comes to securing their systems. With the abundance of information available online, it’s easy to get overwhelmed and confused about the best practices for firewall configuration and basic security.
That’s why I reaching out to the Linux community for help. I am looking users who are willing to share their expertise and write a comprehensive guide to Linux firewall and security.
The goal of this guide is to provide a centralized resource that covers the following topics:
Introduction to Linux firewalls (e.g., firewalld, ufw, etc.)
Understanding basic security principles (e.g., ports, protocols, network traffic)
Configuring firewalls for various scenarios (e.g., home networks, servers, VPNs)
Best practices for securing Linux systems (e.g., password management, package updates, file permissions)
Troubleshooting common issues and errors
Advanced topics (e.g., network segmentation, SELinux, AppArmor)
I am looking for a well-structured and easy-to-follow guide that will help new users understand the fundamentals of Linux firewall and security, while also providing advanced users with a comprehensive resource for reference.
If you’re interested in contributing to this project, please reply to this post with your experience and expertise in Linux firewall and security. We’ll be happy to discuss the details and work together to create a high-quality guide that benefits the Linux community.
Thank you for your time and consideration, and im looking forward to hearing from you!
There is a thing called the OSI model, which is a useful tool for understanding what different components of a computer network do. I suggest looking up that term if you want to learn more about how networks work.
You might be familiar with the idea of IP addresses and MAC addresses. An IP address is routable, as in you can look at an IP address and tell where on the network (and broadly speaking, in the world) it is. A MAC address is assigned to the network adapter during its manufacture, it’s kind of like the machine’s name.
When you get out a sheet of parchment, a well of squid ink and a quill pen and write an old fashioned letter to an acquaintance (ask your parents, they probably used to actually do this), you write both the recipients street address and their name on the envelope. The postal service uses the street address to move the letter to the correct building, and then there’s probably someone in your household who gets the mail out of the mailbox and then says “Jim, this letter is for you.”
Think of a router as a post office; routers send each other data packets based on the recipient IP address. A switch works via MAC addresses and is more like your dad saying “Jim you got a letter.” A hub, which is a technology we don’t use anymore, would be more like your dad reading everyone’s mail out loud for everyone to hear, and everyone else is just supposed to ignore what’s not for them.
Now, let’s talk about a more informal definition of the word “router”: The box with a bunch of wires and probably a couple antennas on it that your Wi-Fi probably comes out of. We call that little box a “router,” and that’s one of the many jobs it does. You can think of networking components as little building blocks, and your home router has many building blocks in it. It’s a little computer with some networking hardware attached, and it likely functions as a router, an Ethernet switch, a wireless access point or two, probably your DHCP server (assigns IP addresses to devices on the network automatically), it probably serves as a firewall, mine can be a print server or a file server.
Thanks a lot! So a switch uses Mac adresses and not the DHCP IPs?
In our basement we had two switches. A long ethernet cable goes from the router there, into one switch, and from that one many cables into another switch, and from that one all the cables go seperately to the rooms. Both switches are supplied with electricity.
Now for some reason ethernet doesnt work anymore, even though I used the correct cables and removed the rest as nobody uses ethernet anymore, just two cables, repeater and my cloud server.
I just used one switch, as I had no idea what you would need two switches for? Before there were 8 cables or so, now only 2
“From that one many cables into another switch” as in, you used more than one cable to plug one switch into another? Yeah that won’t work. Ethernet doesn’t like that kind of thing.
It is valid to connect one switch to another if you need more ethernet ports, but you would connect them with one cable. The best way to do it if possible would be to connect each switch to a port on the router,
Hmm no sorry.
One ethernet cable going down from the router
Two switches, both plugged into power supplies
The ethernet cable goes into the first switch and out go 8 seperate ones. But these dont directly go to the rooms, but to the second switch first, one in one out each and into the rooms.
Yes what you described makes sense. I just removed a switch but now nothing is working which is weird. Will have to test plugging in at each step to see where the failure point is
I think I would have to see a drawing of this.
Understandable, here you go.
I dont get the purpose of switch 2, both are plugged into electricity so seem to be active.
Huh. Yeah that’s some bizarre network architecture right there. It shouldn’t be necessary to connect two boxes with multiple wires like that, and in fact it shouldn’t work at all. You’re saying it doesn’t work if you remove one of the switches? There’s something odd going on there, like these are probably managed switches with some odd configuration happening. If you figure out exactly what it is, let me know, because I think it’d be an interesting learning opportunity.
Yeah… problem is I am the only one caring at all and the rest exists since forever and nobody knows anything. Currently Ethernet didnt work at all so I resetted the router, will check the model numbers of the switches