Does anyone have a good source on explaining subnets, ports, and internal IP addresses?

[Syze00]

Here's kinda where my knowledge is regarding internet/networks but I still don't understand everything enough to be confident.

I know that the internet is split up into layers that are partitioned out for different uses and that my ISP ip isn't going to be my home devices IP since thats provided by my router.  We probably have all seen 192.168.x.x but can you change those numbers completely?  Can I change everything including the 192.168.x.x?  If I change the 2nd to the last number from a 0 to 1, does that make a completely separate network in my home?  

I get ports are used as communication "doors" but I just don't understand why there are so many different ones (like gaming services or other communicating services)

And last, Subnets.  I don't understand what they are or what they do.  I can watch a video on it but sometimes watching a technical video can make you go numb and find yourself reading emails when you should be listening or trying to understand.  Also some of the classes I've purchased from some of the online classes, the teachers accent is so thick I have a hard time getting over that.  That sounds bad but I'm being honest.  I can't learn from them if I can't understand them.

 

If anyone has any recommendations on classes, YT videos, sites, even paid classes.  I would just like to understand this one step deeper.

Thanks in advance.

 

[LIGISTX]

53 minutes ago, Syze00 said:

Here's kinda where my knowledge is regarding internet/networks but I still don't understand everything enough to be confident.

I know that the internet is split up into layers that are partitioned out for different uses and that my ISP ip isn't going to be my home devices IP since thats provided by my router.  We probably have all seen 192.168.x.x but can you change those numbers completely?  Can I change everything including the 192.168.x.x?  If I change the 2nd to the last number from a 0 to 1, does that make a completely separate network in my home?  

I get ports are used as communication "doors" but I just don't understand why there are so many different ones (like gaming services or other communicating services)

And last, Subnets.  I don't understand what they are or what they do.  I can watch a video on it but sometimes watching a technical video can make you go numb and find yourself reading emails when you should be listening or trying to understand.  Also some of the classes I've purchased from some of the online classes, the teachers accent is so thick I have a hard time getting over that.  That sounds bad but I'm being honest.  I can't learn from them if I can't understand them.

 

If anyone has any recommendations on classes, YT videos, sites, even paid classes.  I would just like to understand this one step deeper.

Thanks in advance.

 

Lawrence systems does a very good job imo of explaining all of this. I learned almost all of my networking knowledge via his video, and now have a fully managed, multi vlan pfsense firewalled network…

 

 

 

one video of MANY. I would give a few of his networking ones a watch, maybe search for keywords like subnet and vlan and watch the videos he has. 

[Windows7ge]

I don't have videos to reference you to as my education came directly from CISCO courses and years of personal experimentation. I feel you though when certain delivery methods of information aren't very effective. Like classroom environments and reading pages and pages of text. I'm about as adsorbent as a rock but give me some hardware and I'll play with it and use Google til I figure it out.

 

To explain your curiosity as simply as possible though. With IPv4 there are Private & Public IP ranges. That is what IP's can be routed publicly on the open web and what IP's cannot. Your private ranges are as follows:

Class A: 10.0.0.0 - 10.255.255.255
Class B: 172.16.0.0 - 172.31.255.255
Class C: 192.168.0.0 - 192.168.255.255

Inside these ranges are what you will see inside homes, schools, and businesses. Outside of these are what can be routed publicly on the open web.

 

Your subnet is a network mask that denotes what are network bits and what are host bits. And this can be written three different ways:

192.168.0.0/24
which is identical to
192.168.0.0 255.255.255.0
which is identical to
11000000.1010100.00000000.00000000 11111111.11111111.11111111.00000000

 

 

255 or all 1's in that octet denote how many of those bits are reserved for the network. 0 indicates that none are reserved for the network and that all are available for host utilization. A combination of 0's & 1's in the same octet denote that some bits are reserved for both.

 

So in your example question what would happen if you changed 192.168.0.X to 192.168.1.X. Well, that depends on your net mask. If you're using /24 or 255.255.255.0 then your mod just put that device or router on a completely different network. It will not communicate with devices that are on 192.168.0.X.

 

However if you shrunk the netmask to /23 or 255.255.254.0 now 192.168.1.X has been included in the same network as everything in 192.168.0.X. This gives you a host IP range of 192.168.0.1 - 192.168.1.254. Meaning every client could see each other weather they're on 192.168.0.X or 192.168.1.X but only if you have a /23 subnet. If you have /24 then you've just made a segregated network.

 

The purpose of ports is to enable multiple services to run side by side with one another over a network. For example if you want to run SSH which by default uses Port 22 but you need to connect to a network switch over Telnet you couldn't do that on the same client if they both used the same port. Telnet defaults to port 23 so it's a non-issue but essentially each network service gets a port and it let's multiple network services run simultaneously without them conflicting. It lets each service know who needs incoming data or where outgoing data is headed.

 

That's still a wall of text. Sorry, I did my best to summarize it but the world of networking gets a whole lot more complicated from here. Did I miss any of your questions? Did I just make more questions?

[Syze00]

Me learning this is probably going to be how you learn most things.  Its beaten into your head until your head starts to make sense of it on its own.  I'm still in the struggle phase of learning it and haven't had the "Ah ha!" moment yet like I've had with hooking up AV equipment.

 

What makes this a challenge is that the data is so similar its easy to get slightly confused.  I appreciate the recommendations and the time people have taken to write something out to help.  I really do appreciate it.

 

It's always dangerous when you know enough about a subject to get in trouble...

[Ralphred]

50 minutes ago, Windows7ge said:

Your private ranges are as follows:

It's also worth noting that 224.0.0.0/4 (anything in the 224.x.x.x to 239.x.x.x range re: Starting with 1110 in binary) is reserved for multicast.

[Windows7ge]

8 hours ago, Ralphred said:

It's also worth noting that 224.0.0.0/4 (anything in the 224.x.x.x to 239.x.x.x range re: Starting with 1110 in binary) is reserved for multicast.

Class D yes. I omitted that for the sake of shrinking my wall of text as it wasn't immediately relevant to OPs questions.