Even seasoned network engineers such as myself are confused by IPv6 because, as you noted, it requires us to "forget" everything we know about IPv4 and start from scratch. This is not easy to do but your video has helped me make progress on coming to terms with the IPv6 space. Thank you for providing this excellent resource!
Finally, a good introduction to IPv6. Systematically walking through the development process makes it all come together very nicely at the end. looking forward for more brilliant videos on IPv6 from you!
As a network instructor for many years (decades even!) I totally endorse your approach to describing IPv6 - do NOT try to compare its features with IPv4. It is a new protocol. Loved the address scope explanation. One thing though - it is still the same old UDP and TCP - regardless of the Network layer protocol. Looking forward to your explanation of anycast - that often causes students difficulty (mostly because they try to compare it to broadcast.)
Many thanks Aubrey! W/r to anycast, my preferred analogy is calling the emergency number- you always call the same number but you would land in a different call center depending on the network you place the call from and the time of the day ;-)
He's right though, there's is no TCPv6 or UDPv6. What you're referencing is the field that occurs in the IPv4 and IPv6 header that indicates *what type* of layer 4 header *follows* after the IPv4/v6 header. TCP and UDP are the same for either one.
Absolutely! I don’t contradict ;-) The only reason I emphasize on udpv6 and tcpv6 is to build context for the importance of icmp for the ipv6 protocol ;-)
Personally I feel like the addressing part is not that complicated and not that different from IPv4. IP address of a certain number of bits with a subnet mask of a certain number of bits (cidr) is all the same just longer addresses. The explanation of scopes is good though and important but also this is not too dissimilar to rc1918 addresses. The part I think that a lot of people get confused about is routing, how it happens and why as well as different configuration setups besides SLAAC, like DHCPv6, RA/router advertisements, prefix delegation and interface tracking. A lot of people are used to thinking in terms of NAT which is why I don't disagree with this approach but even without comparison or even mentioning it might be important to stress especially for home users who are used to having to forward ports that this isn't a thing. No forwarding ports, instead you block ports with a firewall on the router or local machine. I'm not sure a lot of people fully understand with IPv6 and a typical home router that their pc is now directly accessible on the public internet instead of hiding behind a NAT (which isn't a firewall - it just doesn't know where to send incoming traffic unless you tell it).. While I understand this is an introduction, I had to understand all of that when setting up my own home network even. Though I still don't understand why I can't seem to track or delegate to my 2nd WAN interface, only get one /56 over dhcp and I can't ask for several smaller prefixes or seem to delegate a /64 or something to secondary wan..works fine for lan interfaces though.. not a huge deal but my ocd doesn't like seeing an adapter with unassigned address.
@@forbiddenera > with IPv6 and a typical home router that their pc is now directly accessible on the public internet that obviously depends on the router, I'm not sure what you mean by "a typical home router" but all the ones I've encountered do not allow incoming traffic by default, as should be true for any network device that isn't garbage.
Excellent introduction to IPv6. I really hope that you will follow this up with many more topics like dual stack, firewalling and others (like VLANs) that an average person needs to understand when creating a small office or home IPv6 network. We are more than happy for you to do this as part of the next OpenWRT episode.
Hi Manoj, the topics that you mention are definitely the right ones - I'd add to these: Unicast, Anycast, Multicast (Router solicitation, Router Advertisement, Duplicate Address detection), NDP ;-) Thanks for the feedback !!!
The best set of IPv6 videos on youtube. Thanks for the clear and concise explainer. Most stop at a simple explanation of "what is IPv6". You actually explain how to use it. I was finally able to set up IPv6 on my network.
This is an absolutely excellent video and in my opinion it's a must-watch for anyone starting out on IPv6. I can honestly say that if I'd been able to watch this 15 minute introduction when I first looked at IPv6 it would have saved me many many many hours of going back and forth through text books trying to get my head around the concepts - and your approach to explaining it is brilliant, and I totally get what my problem has been until now in learning IPv6 - I was always trying to find an IPv4 analogy! Your video has got me over that hurdle, explained what the fundamentals are and what I should always keep in mind. It's made understanding and mastering the conceptual basis of v6 so much easier. Keep up the good work and I say that as one very Patreon patron!👌👍😄
Hi Ray, first off - thank you very much for being a patron!!! I am so glad that so many people seem to like the video (at least from what I read in the comments) - it looks like disconnecting from IPv4 is really the key for everyone here. Many thanks for the friendly feedback!
The key realisation for me was around the fact that hosts will almost always have multiple IPv6 addresses. Of course we could always have multiple addresses in IPv4 as well, but it was typically the exception rather than the rule. In IPv6, everything has multiple addresses. I also have a /56 prefix delegation from my ISP, and I've enjoyed the challenge of setting this up on my pfSense based firewall / router. Compared to the 1 I(public) Pv4 address , the numbers of IPv6 addresses I get is just staggering!
Hi Aaron - I went through exactly the same experience here. When I saw the many IPv6 addresses on my laptop the first time it totally freaked me out. And - as you say - the size of the address space is just overwhelming ;-)
"Of course we could always have multiple addresses in IPv4 as well, but it was typically the exception rather than the rule." Not entirely true. Your host always has 127.0.0.1 - though that's a bit cheeky. What's less cheeky is if a NIC is configured with address 192.0.2.1/24, it can receive/listen for messages destined to 192.0.2.255 (local broadcast). While not particularly obvious, your host has multiple IP addresses. It just doesn't really send with the broadcast address as source. Your IPv4 host also uses another address - 0.0.0.0. This one comes into play specifically for DHCP. If you look at the source address of a DHCP discover packet, you'll see this as the source address. In fact there's nothing stopping you from say, booting up a host on a network without DHCP (or disabling the DHCP client), grabbing an IPv4 link-local address (APIPA), configuring that statically on the interface, and then re-enabling DHCP for an additional address.
@@Jamesaepp "Your host always has 127.0.0.1" It's actually more than you think ^^. Even though IPv4 has such a limited address space, they dedicated a whole class A net to the local host, not just a single address. 127.0.0.1 is just the most commonly used and is usually mapped locally to "localhost". However 127.45.12.42 is also a local loopback address. The entire 127 net is local loopback. So 1/256th of the whole v4 address space is wasted. In IPv6 they decided that a single address is enough. If you need more, you can always assign more, but it's not implicit. Note that (0.0.0.0) is not really an address, it's merely a wildcard for the whole network to indicate no particular address. As you may know, when binding a socket, you can either bind it to a local address that the socket should listen to, or bind it to (0.0.0.0). That means the socket would be bound to all local addresses. In other words if a packet arrives at your NIC, it doesn't really care what the destination address is. Since it arrived at your NIC, it's meant for you. A lot servers by default bind to (0.0.0.0) so they accept any packets, no matter to which IP they were directed to. However explicit binding is needed if you want to run several servers on the same machine on the same port. You just need to bind each it to different local addresses. Locally you can bind servers to different local host addresses and it would work fine, locally. So you can run a server on 127.0.0.1:5555 and one on 127.0.0.2:5555. Of course you can only connect to those two servers locally, so this is just an example. Though If you bind a server to (0.0.0.0), you can't bind another socket to the same port as it 0.0.0.0 binds to all addresses. A single end point (IP + protocol + port) can only be used / bound once.
Thank you Marc. Your video helped me to turn the fear, to something that looked very strange, into a will to delve further into it to learn something new. With your guidance, I am ready to take that journey and learn along from your future videos about this topic.
Hi, that's great feedback, many thanks. I experienced exactly the same. It was a great unknown until I took all my courage and stepped into that course. And after all now I realize that it is fun. I'll definitely do follow ups.
Your introduction was spot on. It's still frustrating to me and shutdown ipv6 as much as i can in my home because of it. My modem has a IPv6 address but I have IPv4 on my WAN port. I don't think I need v6 on my LAN. It would just be a learning tool if anything.
Going to learn IPV6 for future reference. For now, I have two lan adaptors on both my desktop and laptop. On each machine, I have one adaptor handling IPV4, and the other handling IPV6. The adaptors handling the IPV6 are ALWAYs moving more data than the IPV4. Almost twice as much sometimes. Anyone hating on IPV6 better get with it. Its more prominent than you think. I have Starlink as an ISP.
Hi Ben, I am honestly and fundamentally happy each time someone tells me that my videos could help them to achieve something. Thanks a lot for your friendly feedback.
Well explained from scratch, thank you Marc. Good approach in asking us to forget what we know about IPv4 and in the end, after all is as clear as muddy water, I would say IPv6 is still quite similar to IPv4
Hi Thomas - yes it is after all. Just people (including myself of course) tend to be "mentally stuck" in NAT. WE tend to forget that NAT is a workaround and that it is not Firewall ;-)
First off let's say brilliant video. Crazy that I'm celebrating my 25th year as a tipple CCIE and I still have never used it. That's going to change today. Wife is born in raised in Kassel in Hesse, go at least 5 times a year from the US. Such an amazing county, love it! Father-in-law was a helicopter pilot in the Bundeswehr, holds all sorts of stunt pilot records it's just insane, and the coolest man ever. He flew me under a bridge one day at 300km/h at 10 Meters from the water, about had to change my shorts. Was based at Heeresflugplatz Fritzlar, to us US folks Fritzlar Air Base, home of the Attack Helicopter Regiment 36. The stuff he showed me there was just mind blowing. Thanks again for starting me on my journey.
Finally a comprehensive explanation... hope you had underlined/marked the digits when talking about subnetting for easy visualization... waiting for your video explaining why broadcast is not anymore... and how anycast mechanism works along the route in the intermediate nodes... ;-)
Thank you Marc for this! Very helpful! I look forward to your IPV6 episode on OPENWRT, it would be super useful to see how to correctly impalement that at home.
This guy is a genius MashAllah what an explanation and how he describe step by step that's wonderful. Amazing, Bravo!! I want a teacher like you, please make more videos on IPV6 Thanks for the good knowledge and explaination.
I just learned about the entire history of TCP and IP. From a modern corporate naming view, we'd probably name IPV4 "IP" and IPV6 "IP Pro/Advanced" as all of the old versions aren't relevant That aside, this video made ipv6 feel so simple. This may be one of the issues why it hasn't seen widespread commercial use yet, its immediate scaryness lol.
Hi, many thanks for the feedback - yes, you may see a lot of strong opinions on IPv6 in other comments here - I do agree it is more a human subject than a technological one that prevents adoption ;-) But I don't want to sound smarty-pants here because I felt exactly the same before ;-)
Thanks Pavel. Yes - as there is so much info floating around everywhere - that was the reason I decided to take that course. I never had to use IPv6 and could safely ignore it. But that left the "there is space to be discovered" voice in my head ;-)
ABSOLUTELY the best one of these I have ever watched...and there have been 100s. I love how you break it all down, and I too struggle with differentiating IPv4 and IPv6. I am still struggling with IPv6 (in my home with pfSense as router and a Windows 2019 server ADDS/DNS/DHCP setup). I cannot get that server to hand out addresses (well I can - but they cannot get to the Internet over IPv6 only (every test site I visit shows IPv6 failures). Looking forward to your other videos, and maybe I can figure this out. 👍
Thank you very very much for this explanation. You're right, you need to forget everything about V4 to understand V6. Without V6 in mind I do now understand why I got so many IPv6 Adressess on my devices. And good to know about Deutsche Telekom. I'm switching to this ISP in two weeks from Vodafone. Knowing my pfSense thats great knowledge :)
Hi Stephan, please do keep in mind that if you want to get a /56 prefix from Deutsche Telekom, then this will not work with their speedport routers (at least the one I had, don't know about the recent ones). I had to replace the Speedport with a DSL Modem ( I am using a VIGOR modem for this) in order to get full IPv6 functionality. Also lowered my ping time by 2 ms.
Hi Eric, interesting topic! I would need to run experiments myself for this, haven't tested it yet - this seems to be a good primer: stevessmarthomeguide.com/multicast-dns/
Thank you for making this video and sharing it with all of us! I have been putting off learning IPv6 for a long time now. This was exactly the correct video for me to find and get motivated to get back into learning this. I am of course, subscribe with notifications turned on, and that was it up.
Hi Marc, I started to watch your IPv6 videos. Great, as mostly all your videos :) Just a comment to the IPv6 Cheat Sheet @ scopes and special adresses. The text goes down from "global" to "link local". But the table starts with localhost, then global and finishes with link-local. I would find it easier to understand if there was always the same direction. And as an inexperienced user, the representation of the ranges in normal form would also be very helpful. Maybe it would be better to integrate "scope" and "description" into the table to make it more easy to understand like this: "SCOPE" | "Range (CIDR)" | "Range" | "Purpose" "UNIQE LOCAL" | "FC00::7" | "FC00" .... "FDFF"" | Everything in our LAN (behind the internet gateway), Henning
About local LANs, while some protocols do use link local addresses, most apps still use GUA or ULA addresses. However, they don't pass through the router. They communicate directly. You can see this by monitoring traffic with Wireshark. Also, when link local addresses are used, it is often necessary to specify which interface is to be used. GUA addresses can start with 2 or 3, but I don't know that 3 is used yet. A single /64 subnet, which is the only size allowed for a LAN, contains 18.4 billion, billion addresses. As mentioned, a /56 prefix is often provided. I have one of those, but some ISPs provide a /48, which is 256x larger. There are enough GUA addresses to give each and every person on earth over 4000 /48s! BTW, I have been running IPv6 on my own LAN for over 12 years. At first, it did take some getting used to. But now I have become the IPv6 expert in some forums. The sooner we can abandon IPv4, the better!
Hi James, I believe that I have seen your name pop up in some of the IPv6 related forums / questions a couple of times. Great to see you here ! Many thanks for the feedback ;-) You are right with everything you say - there are so many IPv6 address spaces - I realize how difficult it is for a human being to grasp exponential models ;-) Also - if I think about people trying to use IPv6 with a single /128 address - that's so disappointing because it makes it impossible for them to discover the real beauty of it ;-(
@@OneMarcFifty Quite so. A lot of people have been misled by the IPv4 address shortage and NAT, to the point they don't understand how things are supposed to work. Incidentally, customers are often provided a /128 for their WAN address. This address cannot be used for routing, as there is only one device supported by it. Even a point to point link must be at least a /127, allowing for 2 devices. A /128 is only used to identify an interface, with routing typically done with a link local address. BTW, If you really want to get into IPv6, I can recommend "IPv6 Essentials", from O'Reilly.
Many thanks for your reply and explanation James. I was thinking about making a video for an IPv6 test lab - enabling viewers to test everything in a sandbox before they go live in the real world. Some are suggesting hurricane electric as 6in4 tunnel. Any opinion on this?
@@OneMarcFifty I started out with a 6in4 tunnel, in May 2010, and it worked well. I wasn't with Hurricane Electric, but I understand they're about the largest tunnel provider. My own ISP started providing native IPv6 almost 7 years ago, but provided 6to4 and 6rd tunnels for a couple of years before that. So, including a 6in4 tunnel would be a good idea, as many are still stuck on an ISP that doesn't provide IPv6.
Thank you for these IPv6 videos. One thing I can't get my head around is my perception that there is a lack of privacy. For example, when you browse to a website, does the website see the complete IPv6 address for the client, or just the WAN portion assigned by the ISP? Does the ISP know what devices you have on your LAN? How do you handle port forwarding? I assume you would still need to open ports on your router's firewall and on your client's software firewall. All of these privacy related questions are fairly simple in IPv4, although, I do understand they are byproducts of NAT, which apparently is a bad thing (though I like it for network segregation and privacy). What am I missing here with IPv6? Why do the LAN clients even need to be aware of the WAN IP from the ISP?
Hi, that's very kind of you - thank you very much. It's only after that video and people leaving comments that I realized I had been saying it wrong for over 30 years ;-)
I thought of taking that Udemy course (the 17h one, right?) to understand some of the differences from IPv4 that despite managing IP networks from the late 90s and using IPv6 for about 3 years, I wasn't able to understand, your videos were just what I was missing, these two and the OpenWRT one! Thanks a lot!
03:40 and 3:58 Please note you always HAVE TO shorten the longest run of consecutive 16bit 0 fields, therefore FF:0:0:0:1::1 would be wrong too. When the length of the consecutive 16-bit 0 fields are equal, the first sequence of zero bits MUST be shortened.
Hi Nick, many thanks for the friendly comment. Yes - when I launched my "IPv6 only" testlab I realized how bad the coverage is really. ISPs, content providers, CDNs - there's still a lot of room of improvement left ;-)
Wondering if its the same course I started months ago but after the header stuff and the mass of special address spaces eventualy forgot about xD I watched alot of the paid courses on Udemy and LinkinLearning the past 3 years, and like Prof Messer here on YT, your videos and the way you present dense highly technical content in an understandable maner, for free, is nothing short of amazing and I thank you for doing so! Some say you best learn IPv6 by turning off IPv4 on your network and start from there ;)
Ideal scenarios and simple explanations are right on point and will be great to add other techniques and examples, such as building an IPV6 LAN with router and hosts using only IPV6, also configuring a DNS server to serve your IPV6 site out to the internet, ssh, ping6, traceroute and other tools to diagnose issues and troubleshoot IPV6 only without involving IPv4 anymore. Thank you again! looking forward to the next one.
Wow -someone is opening the box of pandora, often thinking about it, never dared to. Okay watched the video, very good start, what itnerests me the most: what about security? Without NAT I feel a bit naked ;-)
Yeah - I felt the same honestly- but let’s not forget that NAT is just a workaround ;-) Firewall will do its job - with or without NAT. Privacy concerns could be addressed by changing the ipv6 frequently- as there are so many possible addresses it could in fact even be an improvement!
@@OneMarcFifty thanks for the awesome video, what I don't understand is if with ipv6 it will still be possible to hide your internal hosts from the outside world without them losing internet connectivity. Maybe i get it wrong but It seems this protocol implies no NAT so every device who needs internet connectivity must have a public ipv6 address. What if I don't want my crappy chinese IOT device to have a public ip address in first place ?
Great video! Could you please shortly reply to this question: Which Internet > Type of Connection > IPv6 Connectivity have you enabled in your FRITZ!Box?
Many thanks Naveen. I really wanted to give viewers something to take away. Also I admit that I wanted to do a bit of publicity for my github repos ;-)
Thank you much for the easy simplified way of delivering that content I do recommend you to teach on udemy your courses will be very good add to the tech community
This is pretty funny....you say to start over because it isn't similar to ipv4....yet, it is, just bigger and mapped better. The only real difference is shrink notation, and that's easy enough, but it would be highly inefficient of a system to use arbitrary addresses for people, so it makes sense to cut down subs within the mask. It also makes sense that it would be first-in read routing, so as soon as the router knows enough information, it sets up the packet for delivery immediately down the line....so with those, it is obvious that you are going to have layers from front to back mean global toward local, this is exactly ipv4.
Hi Robert, many thanks for the feedback. I never said it's not similar (or let's rather say comparable) to IPv4. I just said it helped me to forget everything about IPv4. The main reason for this was that I kept looking for a translation mechanism between private and public addresses (I was kind of locked into NAT thinking). IPv6 solves this with prefix delegation and subnetting the global address space which either does not exist in IPv4 or cant be done by end users because they would never get a subnet to play with (because of the smaller address space).
Super gemacht! Wünschte mir mehr Infos zu Prefix Delegation, DNS bei Ipv6 (warum gibt es den bei einigen Routern zum Eintragen, bei anderen nicht), Gateway (ist das der nächste Hop oder der Router mit dem Prefix?), IGMP Proxy.
Even seasoned network engineers such as myself are confused by IPv6 because, as you noted, it requires us to "forget" everything we know about IPv4 and start from scratch. This is not easy to do but your video has helped me make progress on coming to terms with the IPv6 space. Thank you for providing this excellent resource!
Finally, a good introduction to IPv6. Systematically walking through the development process makes it all come together very nicely at the end. looking forward for more brilliant videos on IPv6 from you!
Hi Lionel, many thanks for your feedback. There will be a follow up.
As a network instructor for many years (decades even!) I totally endorse your approach to describing IPv6 - do NOT try to compare its features with IPv4. It is a new protocol. Loved the address scope explanation. One thing though - it is still the same old UDP and TCP - regardless of the Network layer protocol. Looking forward to your explanation of anycast - that often causes students difficulty (mostly because they try to compare it to broadcast.)
Many thanks Aubrey! W/r to anycast, my preferred analogy is calling the emergency number- you always call the same number but you would land in a different call center depending on the network you place the call from and the time of the day ;-)
He's right though, there's is no TCPv6 or UDPv6. What you're referencing is the field that occurs in the IPv4 and IPv6 header that indicates *what type* of layer 4 header *follows* after the IPv4/v6 header. TCP and UDP are the same for either one.
Absolutely! I don’t contradict ;-) The only reason I emphasize on udpv6 and tcpv6 is to build context for the importance of icmp for the ipv6 protocol ;-)
Personally I feel like the addressing part is not that complicated and not that different from IPv4. IP address of a certain number of bits with a subnet mask of a certain number of bits (cidr) is all the same just longer addresses.
The explanation of scopes is good though and important but also this is not too dissimilar to rc1918 addresses.
The part I think that a lot of people get confused about is routing, how it happens and why as well as different configuration setups besides SLAAC, like DHCPv6, RA/router advertisements, prefix delegation and interface tracking.
A lot of people are used to thinking in terms of NAT which is why I don't disagree with this approach but even without comparison or even mentioning it might be important to stress especially for home users who are used to having to forward ports that this isn't a thing. No forwarding ports, instead you block ports with a firewall on the router or local machine. I'm not sure a lot of people fully understand with IPv6 and a typical home router that their pc is now directly accessible on the public internet instead of hiding behind a NAT (which isn't a firewall - it just doesn't know where to send incoming traffic unless you tell it)..
While I understand this is an introduction, I had to understand all of that when setting up my own home network even.
Though I still don't understand why I can't seem to track or delegate to my 2nd WAN interface, only get one /56 over dhcp and I can't ask for several smaller prefixes or seem to delegate a /64 or something to secondary wan..works fine for lan interfaces though.. not a huge deal but my ocd doesn't like seeing an adapter with unassigned address.
@@forbiddenera
> with IPv6 and a typical home router that their pc is now directly accessible on the public internet
that obviously depends on the router, I'm not sure what you mean by "a typical home router" but all the ones I've encountered do not allow incoming traffic by default, as should be true for any network device that isn't garbage.
Thank you. For years I've only ever seen "Enable it vs. Disable it" with all kinds of myths. Nice to finally have an explanation!
This is the most clean explanation of IPv6 I’ve ever seen. You are killing it Marc, thanks!
Many thanks Remy!
Excellent introduction to IPv6. I really hope that you will follow this up with many more topics like dual stack, firewalling and others (like VLANs) that an average person needs to understand when creating a small office or home IPv6 network. We are more than happy for you to do this as part of the next OpenWRT episode.
Hi Manoj, the topics that you mention are definitely the right ones - I'd add to these: Unicast, Anycast, Multicast (Router solicitation, Router Advertisement, Duplicate Address detection), NDP ;-) Thanks for the feedback !!!
The best set of IPv6 videos on youtube. Thanks for the clear and concise explainer. Most stop at a simple explanation of "what is IPv6". You actually explain how to use it. I was finally able to set up IPv6 on my network.
This is an absolutely excellent video and in my opinion it's a must-watch for anyone starting out on IPv6. I can honestly say that if I'd been able to watch this 15 minute introduction when I first looked at IPv6 it would have saved me many many many hours of going back and forth through text books trying to get my head around the concepts - and your approach to explaining it is brilliant, and I totally get what my problem has been until now in learning IPv6 - I was always trying to find an IPv4 analogy! Your video has got me over that hurdle, explained what the fundamentals are and what I should always keep in mind. It's made understanding and mastering the conceptual basis of v6 so much easier. Keep up the good work and I say that as one very Patreon patron!👌👍😄
Hi Ray, first off - thank you very much for being a patron!!! I am so glad that so many people seem to like the video (at least from what I read in the comments) - it looks like disconnecting from IPv4 is really the key for everyone here. Many thanks for the friendly feedback!
thank you for this great intro to IPv6, it's very helpful and you explain it very well in simple terms.
My boss tasked me to “git gud” on ipv6. And I’m so happy this was the first video I chose to watch.
The key realisation for me was around the fact that hosts will almost always have multiple IPv6 addresses. Of course we could always have multiple addresses in IPv4 as well, but it was typically the exception rather than the rule. In IPv6, everything has multiple addresses.
I also have a /56 prefix delegation from my ISP, and I've enjoyed the challenge of setting this up on my pfSense based firewall / router. Compared to the 1 I(public) Pv4 address , the numbers of IPv6 addresses I get is just staggering!
Hi Aaron - I went through exactly the same experience here. When I saw the many IPv6 addresses on my laptop the first time it totally freaked me out. And - as you say - the size of the address space is just overwhelming ;-)
"Of course we could always have multiple addresses in IPv4 as well, but it was typically the exception rather than the rule."
Not entirely true. Your host always has 127.0.0.1 - though that's a bit cheeky.
What's less cheeky is if a NIC is configured with address 192.0.2.1/24, it can receive/listen for messages destined to 192.0.2.255 (local broadcast). While not particularly obvious, your host has multiple IP addresses. It just doesn't really send with the broadcast address as source.
Your IPv4 host also uses another address - 0.0.0.0. This one comes into play specifically for DHCP. If you look at the source address of a DHCP discover packet, you'll see this as the source address.
In fact there's nothing stopping you from say, booting up a host on a network without DHCP (or disabling the DHCP client), grabbing an IPv4 link-local address (APIPA), configuring that statically on the interface, and then re-enabling DHCP for an additional address.
@@Jamesaepp "Your host always has 127.0.0.1"
It's actually more than you think ^^. Even though IPv4 has such a limited address space, they dedicated a whole class A net to the local host, not just a single address. 127.0.0.1 is just the most commonly used and is usually mapped locally to "localhost". However 127.45.12.42 is also a local loopback address. The entire 127 net is local loopback. So 1/256th of the whole v4 address space is wasted. In IPv6 they decided that a single address is enough. If you need more, you can always assign more, but it's not implicit.
Note that (0.0.0.0) is not really an address, it's merely a wildcard for the whole network to indicate no particular address. As you may know, when binding a socket, you can either bind it to a local address that the socket should listen to, or bind it to (0.0.0.0). That means the socket would be bound to all local addresses. In other words if a packet arrives at your NIC, it doesn't really care what the destination address is. Since it arrived at your NIC, it's meant for you.
A lot servers by default bind to (0.0.0.0) so they accept any packets, no matter to which IP they were directed to. However explicit binding is needed if you want to run several servers on the same machine on the same port. You just need to bind each it to different local addresses. Locally you can bind servers to different local host addresses and it would work fine, locally. So you can run a server on 127.0.0.1:5555 and one on 127.0.0.2:5555. Of course you can only connect to those two servers locally, so this is just an example. Though If you bind a server to (0.0.0.0), you can't bind another socket to the same port as it 0.0.0.0 binds to all addresses. A single end point (IP + protocol + port) can only be used / bound once.
It seems that the world will never move on from ipv4
I'm a beginner so everything you say is strange but the cheat sheet helped me get curious and you've helped me grasp this subject. Amazing video !
Thank you Marc. Your video helped me to turn the fear, to something that looked very strange, into a will to delve further into it to learn something new. With your guidance, I am ready to take that journey and learn along from your future videos about this topic.
Hi, that's great feedback, many thanks. I experienced exactly the same. It was a great unknown until I took all my courage and stepped into that course. And after all now I realize that it is fun. I'll definitely do follow ups.
@@OneMarcFifty thanks
Your introduction was spot on. It's still frustrating to me and shutdown ipv6 as much as i can in my home because of it. My modem has a IPv6 address but I have IPv4 on my WAN port. I don't think I need v6 on my LAN. It would just be a learning tool if anything.
Hi J B, yes - I totally agree - the fun is limited if you only get it LAN-side ;-(
Awesome video. I'm impressed with your teaching skills, making a hard topic easy to understand. It requires a lot of preparation. Many thanks.
Hi David, thank you very much- yes, it does require preparation.
Going to learn IPV6 for future reference. For now, I have two lan adaptors on both my desktop and laptop. On each machine, I have one adaptor handling IPV4, and the other handling IPV6. The adaptors handling the IPV6 are ALWAYs moving more data than the IPV4. Almost twice as much sometimes. Anyone hating on IPV6 better get with it. Its more prominent than you think. I have Starlink as an ISP.
Nice job. Thank you for putting this together and sharing. IPv6 is much clearer for me.
Hi Robert. Awesome - I am glad it could help.
Needed just a few extra words and seconds to cover the '/N' part for number of bits (counted from which end, etc.).
Rather good.
Many thanks Philip.
Every single video you make…. They help me a lot with my network understanding. Thank you very much for all the effort you take doing them!
Hi Ben, I am honestly and fundamentally happy each time someone tells me that my videos could help them to achieve something. Thanks a lot for your friendly feedback.
Another great video from you. I'm really looking forward to upcomming videos about IPv6.
Many thanks Volker!
Well explained from scratch, thank you Marc. Good approach in asking us to forget what we know about IPv4 and in the end, after all is as clear as muddy water, I would say IPv6 is still quite similar to IPv4
Hi Thomas - yes it is after all. Just people (including myself of course) tend to be "mentally stuck" in NAT. WE tend to forget that NAT is a workaround and that it is not Firewall ;-)
It definitely was the best explanation of the protocol I have seen.
Many thanks.
First off let's say brilliant video. Crazy that I'm celebrating my 25th year as a tipple CCIE and I still have never used it. That's going to change today.
Wife is born in raised in Kassel in Hesse, go at least 5 times a year from the US. Such an amazing county, love it! Father-in-law was a helicopter pilot in the Bundeswehr, holds all sorts of stunt pilot records it's just insane, and the coolest man ever. He flew me under a bridge one day at 300km/h at 10 Meters from the water, about had to change my shorts. Was based at Heeresflugplatz Fritzlar, to us US folks Fritzlar Air Base, home of the Attack Helicopter Regiment 36. The stuff he showed me there was just mind blowing. Thanks again for starting me on my journey.
Flying under a bridge is to IPv6 what apples are to oranges. Not even oranges. More like dust bin cover screws. Duuuude!
Finally a comprehensive explanation...
hope you had underlined/marked the digits when talking about subnetting for easy visualization...
waiting for your video explaining why broadcast is not anymore... and how anycast mechanism works along the route in the intermediate nodes...
;-)
Hey, thanks so much for your feedback. True, I should have visualized subnetting more. The follow up episode is available on my channel page btw ;-)
Thank you Marc for this! Very helpful! I look forward to your IPV6 episode on OPENWRT, it would be super useful to see how to correctly impalement that at home.
Thank you very much! I'll need to plan this episode - i've got some ideas but I'll probably set up a whole IPv6 test lab for that. I'll be back ;-)
This guy is a genius MashAllah what an explanation and how he describe step by step that's wonderful. Amazing, Bravo!! I want a teacher like you, please make more videos on IPV6 Thanks for the good knowledge and explaination.
This is the best free software Ive seen. Respect.
Thank you.
Thanks Mark, fantastic explanation.🖖
Thank you very much - I am glad you liked it.
I just learned about the entire history of TCP and IP. From a modern corporate naming view, we'd probably name IPV4 "IP" and IPV6 "IP Pro/Advanced" as all of the old versions aren't relevant
That aside, this video made ipv6 feel so simple. This may be one of the issues why it hasn't seen widespread commercial use yet, its immediate scaryness lol.
Hi, many thanks for the feedback - yes, you may see a lot of strong opinions on IPv6 in other comments here - I do agree it is more a human subject than a technological one that prevents adoption ;-) But I don't want to sound smarty-pants here because I felt exactly the same before ;-)
How to make fun from crazy IPv6 mess :-) Good job.
Thanks Pavel. Yes - as there is so much info floating around everywhere - that was the reason I decided to take that course. I never had to use IPv6 and could safely ignore it. But that left the "there is space to be discovered" voice in my head ;-)
Amazing way to simply everything! Can’t wait for the next video!
Hi Alex, thank you!
I love IPV6, which I think is just better.
Hi Damalia, I have learnt to love it as well ;-)
Finally a IPV6 fundamentals that kept my attention 😄👍💯
ABSOLUTELY the best one of these I have ever watched...and there have been 100s. I love how you break it all down, and I too struggle with differentiating IPv4 and IPv6. I am still struggling with IPv6 (in my home with pfSense as router and a Windows 2019 server ADDS/DNS/DHCP setup). I cannot get that server to hand out addresses (well I can - but they cannot get to the Internet over IPv6 only (every test site I visit shows IPv6 failures). Looking forward to your other videos, and maybe I can figure this out. 👍
Excellent and entertaining explanations. Thanks!
Many thanks Jörg - glad you liked it ;-)
Thank you very very much for this explanation. You're right, you need to forget everything about V4 to understand V6. Without V6 in mind I do now understand why I got so many IPv6 Adressess on my devices.
And good to know about Deutsche Telekom. I'm switching to this ISP in two weeks from Vodafone. Knowing my pfSense thats great knowledge :)
Hi Stephan, please do keep in mind that if you want to get a /56 prefix from Deutsche Telekom, then this will not work with their speedport routers (at least the one I had, don't know about the recent ones). I had to replace the Speedport with a DSL Modem ( I am using a VIGOR modem for this) in order to get full IPv6 functionality. Also lowered my ping time by 2 ms.
@@OneMarcFifty hey Marc,
Thanks for the hint. No worries, i bought a zyxel Modem to avoid the speedports 😂
very good👍
I was wondering how to play with ipv6 on my network and this helps a lot.
I haven't watched the whole video yet but I love the idea behind your approach.
that was very helpful Marc. The biggest single piece of advice that really helped was to forget IPv4. That really made a big difference. 😀👍
Hi, thanks for the feed back ;-) Yes, that was big (yet simple) discovery for me as well ;-)
This is a great intro to IPv6. Thank you!
Many thanks Stephan.
Great explanation! I'd love to see a primer on .local TLDs in the IPv6 world
Hi Eric, interesting topic! I would need to run experiments myself for this, haven't tested it yet - this seems to be a good primer: stevessmarthomeguide.com/multicast-dns/
Powerful explanation! Thank you! Much clearer now
Many thanks Roy.
Tremendous! Absolutely fantastic presentation. You're one heck of a great presenter!
Thank you very much ;-)
This is great explanation, took out IPv4 concept is really helping to understand IPv6 concept
Many thanks for the feedback, benediktus
This was very helpful, thank you. I might even be able to start using the IPV6 settings on my router.
Hi Mark, that’s great. There will be episodes on how to use it with routers. At least for OpenWrt and maybe for OPNSense/pfSense
Another video with marc, making easy the hard things.
Hi luis, thank you ;-)
Thank you so much bro. Sending virtual hugs. Worked like a charm ;-)
Hi, thank you very much
This was really helpful. Building it up was a great way to help me understand why it is the way it is!
Hi Marc, Great explanation. You are righ, it helps to forget IPV4 and start over :) Thank you.
Hi Bruce, many thanks for the feedback. Glad to hear that I am not the only person making that experience ;-)
Simple method, many thanks for sharing
Hi Sandra, many thanks for watching.
This was an excellent introduction, same with your follow up video. 👍
I made it finally, I forgot IPv4!!
Great content, still having some doubts though. See you on Discord ;)
Hi Euxhenio - great to hear ;-) But don't forget to remember it again in the end ;-)
thank you so much. keep making videos you explain so well
Great introduction for the IPv6 world. Thanks for sharing.
Thank you for making this video and sharing it with all of us! I have been putting off learning IPv6 for a long time now. This was exactly the correct video for me to find and get motivated to get back into learning this. I am of course, subscribe with notifications turned on, and that was it up.
Hi Marc,
I started to watch your IPv6 videos. Great, as mostly all your videos :)
Just a comment to the IPv6 Cheat Sheet @ scopes and special adresses.
The text goes down from "global" to "link local". But the table starts with localhost, then global and finishes with link-local. I would find it easier to understand if there was always the same direction. And as an inexperienced user, the representation of the ranges in normal form would also be very helpful.
Maybe it would be better to integrate "scope" and "description" into the table to make it more easy to understand
like this:
"SCOPE" | "Range (CIDR)" | "Range" | "Purpose"
"UNIQE LOCAL" | "FC00::7" | "FC00" .... "FDFF"" | Everything in our LAN (behind the internet gateway),
Henning
maybe adding the abbreviations like ULA, SLAAC to the table is helpful to ...
Hi Henning, maybe this has already been fixed on the Github - github.com/onemarcfifty/cheat-sheets/blob/main/networking/ipv6.md
About local LANs, while some protocols do use link local addresses, most apps still use GUA or ULA addresses. However, they don't pass through the router. They communicate directly. You can see this by monitoring traffic with Wireshark. Also, when link local addresses are used, it is often necessary to specify which interface is to be used.
GUA addresses can start with 2 or 3, but I don't know that 3 is used yet.
A single /64 subnet, which is the only size allowed for a LAN, contains 18.4 billion, billion addresses.
As mentioned, a /56 prefix is often provided. I have one of those, but some ISPs provide a /48, which is 256x larger. There are enough GUA addresses to give each and every person on earth over 4000 /48s!
BTW, I have been running IPv6 on my own LAN for over 12 years. At first, it did take some getting used to. But now I have become the IPv6 expert in some forums. The sooner we can abandon IPv4, the better!
Hi James, I believe that I have seen your name pop up in some of the IPv6 related forums / questions a couple of times. Great to see you here ! Many thanks for the feedback ;-) You are right with everything you say - there are so many IPv6 address spaces - I realize how difficult it is for a human being to grasp exponential models ;-) Also - if I think about people trying to use IPv6 with a single /128 address - that's so disappointing because it makes it impossible for them to discover the real beauty of it ;-(
@@OneMarcFifty Quite so. A lot of people have been misled by the IPv4 address shortage and NAT, to the point they don't understand how things are supposed to work. Incidentally, customers are often provided a /128 for their WAN address. This address cannot be used for routing, as there is only one device supported by it. Even a point to point link must be at least a /127, allowing for 2 devices. A /128 is only used to identify an interface, with routing typically done with a link local address.
BTW, If you really want to get into IPv6, I can recommend "IPv6 Essentials", from O'Reilly.
Many thanks for your reply and explanation James. I was thinking about making a video for an IPv6 test lab - enabling viewers to test everything in a sandbox before they go live in the real world. Some are suggesting hurricane electric as 6in4 tunnel. Any opinion on this?
@@OneMarcFifty I started out with a 6in4 tunnel, in May 2010, and it worked well. I wasn't with Hurricane Electric, but I understand they're about the largest tunnel provider. My own ISP started providing native IPv6 almost 7 years ago, but provided 6to4 and 6rd tunnels for a couple of years before that. So, including a 6in4 tunnel would be a good idea, as many are still stuck on an ISP that doesn't provide IPv6.
Thank you for these IPv6 videos. One thing I can't get my head around is my perception that there is a lack of privacy. For example, when you browse to a website, does the website see the complete IPv6 address for the client, or just the WAN portion assigned by the ISP? Does the ISP know what devices you have on your LAN? How do you handle port forwarding? I assume you would still need to open ports on your router's firewall and on your client's software firewall.
All of these privacy related questions are fairly simple in IPv4, although, I do understand they are byproducts of NAT, which apparently is a bad thing (though I like it for network segregation and privacy). What am I missing here with IPv6? Why do the LAN clients even need to be aware of the WAN IP from the ISP?
I like the look of IPv6 addresses and prefer them over IPv4 actually!
don't judge an address by its look would be the lesson to me then ;-)
Thanks for sharing your knowledge!
Thank you - you’re welcome.
Learned a lot from your videos, loving the way you say host 😂
Hi, that's very kind of you - thank you very much. It's only after that video and people leaving comments that I realized I had been saying it wrong for over 30 years ;-)
Ah... Great video. I knew I would have to learn this stuff one day. So far my ISP has not implemented IPv6 yet... but I live in Wyoming.
Hi Matthew - I think we are all the same ;-) We know we have to do this one day ;-)
Simply the BEST IPV6 video so far !
Thank you so much!
+1 subscriber here !
Hi Igor - first and foremost - many thanks for subscribing. Glad you liked the video.
I thought of taking that Udemy course (the 17h one, right?) to understand some of the differences from IPv4 that despite managing IP networks from the late 90s and using IPv6 for about 3 years, I wasn't able to understand, your videos were just what I was missing, these two and the OpenWRT one!
Thanks a lot!
Hi Didi, glad you could use it! I can't remember where the course was listed - but it was long. Really long ;-)
03:40 and 3:58 Please note you always HAVE TO shorten the longest run of consecutive 16bit 0 fields, therefore FF:0:0:0:1::1 would be wrong too.
When the length of the consecutive 16-bit 0 fields are equal, the first sequence of zero bits MUST be shortened.
Hi Adrian, I was not aware of this. Is there any official documentation on this ?
@@OneMarcFifty Hi Marc, yes there is. Feel free to have a look at RFC 5952 section 4.2
Thank you - just checked it. It is explicit and states MUST. It even goes further and says that a..f MUST be written in lowercase!
You deserve more than like, thank you
Awesome video. I've finally started to understand ipv6 🎉
Excellent clarity of thought as always. Still waiting for Virgin Media/UK to implement IPv6...
Hi Nick, many thanks for the friendly comment. Yes - when I launched my "IPv6 only" testlab I realized how bad the coverage is really. ISPs, content providers, CDNs - there's still a lot of room of improvement left ;-)
Excellent video. Extremely helpful.
Many thanks Torin !
Mark this is simply awesome! Thank you very much!! Looking forward for the OpenWrt IPv6 implementation video :D
Hi Tomás - thank you so much for your feedback. Yes - I am already planning follow ups - just need to make up my mind which one to do first ;-)
That was excellent! Thank you very much for this walkthrough.
Thank you - glad you liked it
Thank you!! Very informative and fun to watch :)
Wondering if its the same course I started months ago but after the header stuff and the mass of special address spaces eventualy forgot about xD
I watched alot of the paid courses on Udemy and LinkinLearning the past 3 years, and like Prof Messer here on YT, your videos and the way you present dense highly technical content in an understandable maner, for free, is nothing short of amazing and I thank you for doing so!
Some say you best learn IPv6 by turning off IPv4 on your network and start from there ;)
Many thanks for the feedback :-)
Ideal scenarios and simple explanations are right on point and will be great to add other techniques and examples, such as building an IPV6 LAN with router and hosts using only IPV6, also configuring a DNS server to serve your IPV6 site out to the internet, ssh, ping6, traceroute and other tools to diagnose issues and troubleshoot IPV6 only without involving IPv4 anymore. Thank you again! looking forward to the next one.
Hi Jairu, great to hear from you. Looks like the video gets some traction so there will be a follow up. All the best.
Wow -someone is opening the box of pandora, often thinking about it, never dared to. Okay watched the video, very good start, what itnerests me the most: what about security? Without NAT I feel a bit naked ;-)
Yeah - I felt the same honestly- but let’s not forget that NAT is just a workaround ;-) Firewall will do its job - with or without NAT. Privacy concerns could be addressed by changing the ipv6 frequently- as there are so many possible addresses it could in fact even be an improvement!
@@OneMarcFifty thanks for the awesome video, what I don't understand is if with ipv6 it will still be possible to hide your internal hosts from the outside world without them losing internet connectivity. Maybe i get it wrong but It seems this protocol implies no NAT so every device who needs internet connectivity must have a public ipv6 address. What if I don't want my crappy chinese IOT device to have a public ip address in first place ?
Great video! Could you please shortly reply to this question: Which Internet > Type of Connection > IPv6 Connectivity have you enabled in your FRITZ!Box?
Great video! Kudos for the cheat sheet style approach ✨.
Many thanks Naveen. I really wanted to give viewers something to take away. Also I admit that I wanted to do a bit of publicity for my github repos ;-)
Awesome explenation, helped me a lot
Thank you Arne, glad you could use it!
thank you for teaching me sir. 🎈🙂❤👍🎈
Amazing content as usual, I was waiting for this one! :)
Hi Marco, many thanks. Glad you liked it.
This is actually a very good explaination of ipv6 thanks !
Thank you much for the easy simplified way of delivering that content
I do recommend you to teach on udemy your courses will be very good add to the tech community
Thank you thank you thank you!!! Such a clear and well explained video!
This is pretty funny....you say to start over because it isn't similar to ipv4....yet, it is, just bigger and mapped better. The only real difference is shrink notation, and that's easy enough, but it would be highly inefficient of a system to use arbitrary addresses for people, so it makes sense to cut down subs within the mask. It also makes sense that it would be first-in read routing, so as soon as the router knows enough information, it sets up the packet for delivery immediately down the line....so with those, it is obvious that you are going to have layers from front to back mean global toward local, this is exactly ipv4.
Hi Robert, many thanks for the feedback. I never said it's not similar (or let's rather say comparable) to IPv4. I just said it helped me to forget everything about IPv4. The main reason for this was that I kept looking for a translation mechanism between private and public addresses (I was kind of locked into NAT thinking). IPv6 solves this with prefix delegation and subnetting the global address space which either does not exist in IPv4 or cant be done by end users because they would never get a subnet to play with (because of the smaller address space).
Great video mate, really well done.
Absolutely perfect 👍
Thank you ;-)
Mark you are a legend
Thanks mate ;-)
Super gemacht! Wünschte mir mehr Infos zu Prefix Delegation, DNS bei Ipv6 (warum gibt es den bei einigen Routern zum Eintragen, bei anderen nicht), Gateway (ist das der nächste Hop oder der Router mit dem Prefix?), IGMP Proxy.
Very clear tutorial. Thanks 👍
Hi Stuart, many thanks.
du bist ein Chef, danke
good work king, love you
Hey, many thanks ;-)
Forget everything about IPv4, that's good, otherwise you could only conclude that IPv6 was designed by 30 IQ drooling slime molds.
Ah - another strong opinion ;-) Thanks for your feedback ;-)
Very nice intro, thanks!
Thanks Marc!
Hi Michał, you’re welcome.
Referred by Awesome Opensource!!
Cool, many thanks! Say hello to Brian on my behalf! Love his channel ;-)
"Forget everything you know about IPv4". Done and done! Wait, what is IPvX? 13 minutes to find out I guess.
Don’t forget to remember IPv4 again ;-)
Superbly clear - thanks!
It's time to move to IPv6 guys !!!!
Hi , I'd say at least have a look and start to get your hands on it ;-)
Still confused but not as confused. Thank you :)
That's a good start ;-)