I've got difficulties in understanding NAT, NAPT, and port forwarding.
I got what NAT does. But when I try to describe port forwarding, NAT's concept becomes too vague.
I found NAPT and there is only a vague assumption that port forwarding is related to this.
Is port forwarding related to NAPT? If not, what is the difference?
NAPT stands for Network Address Port Translation and it specifically is in reference to be able to have many private IP addresses (ie - inside your building) all able to share a single public IP address (that would be assigned to your router from your ISP).
Think of it like this ... your public IP Address which is visible to the entire Internet exists on the ethernet port that you have connected to your Internet service.
Then, the other ports on your router / firewall / WiFi are all on a different network entirely - that's called your PRIVATE network.
In order to get all of those IP addresses on the inside private network to be able to have autonomous access to the Internet, your router/firewall does what we traditionally call NATting - Network Address Translation. So lets say that you and three other people access the same web site from inside your house... your firewall will see those requests to access that web site on your three different private IP addresses and it will assign to that browsing session, a unique session ID to that datastream and it will then go out and contact that web server but that unique session id rides with that datastream so that when packets come back from the web site the router knows which private IP address to send them to ... it acts as a facilitator for the internet packets going to and from the private IP addresses inside your building.
And a private IP address can be assigned to computers, tablets, cell phones, printers etc. etc.
PORT ADDRESS TRANSLATION is the exact same thing, only in reverse.
You do NOT want anyone on the Internet to be able to access any of the devices on your private network, so by default, your router/fireall denys any requests coming from somewhere on the internet that might be trying to access your public IP address.
But there are times when you have something running on one of your private IP devices ... like a gaming console, or maybe a remote desktop session that you need someone to access from the Internet ... what we typically do, is go into the routers configuration settings, and we create a PAT rule that says, "Allow any attempts to access my public IP address ON this specific port number and send those requests back to this specific private IP address." - in a nut shell.
NATting is when traffic is generated from the inside of your private network and it is going out to the Internet where PATting is for traffic coming FROM the Internet into your private network.
Hope that help clarify things a little ...
Edit: I should point out, that these days, when a device or some software running on your computer needs to allow traffic from the Internet to reach it, there is a feature in most home routers called UPNP (Universal Plug And Play) that, when enabled, devices like XBOX and other software can create - on the fly and without you having to give it any thought at all - PAT rules inside your firewall. UPNP was created because most home users don't remotely understand how network traffic works so trying to teach the non-tech person how to create PAT rules was becoming an issue, so UPnP was invented... it has its issues, but for the most part it's fairly reliable and nothing to worry about.
Related
I have a raspberry pi connected to my router with a local IP. I want to access the raspberry pi from outside (from another country) the local network via web browser. So, I have purchased a VPS which has its public IP.
Now how can I assign this VPS IP to the raspberry pi or any other local devices?
how can I assign this VPS IP to the raspberry pi or any other local devices?
That's not how the internet works.
In short, the VPS provider has a pool of IPs and it or its ISP is responsible for publishing routes to the rest of the internet, informing the rest of the internet how to route to those IPs.
You can't just "move" the public IP to your local network; the rest of the internet won't route traffic to it. It would be kind of like writing "1600 Pennsylvania avenue" on the front of your house - you wouldn't cause you to get White House mail, right? Because regardless of what you write there, the post office doesn't use it as a source of truth for mail routing.
There's a few of the options you have:
use ngrok to expose an endpoint to your local service. Ngrok's servers can proxy connections back to your local environment without it having to be online. This will be accessible by anyone on the internet, but is more obscure than an ipv4 address which can and will be easily found (see below). This is a quick and easy solution, and what I'd recommend in your case.
you already have the VPS. Run the code there instead of on the raspberry pi. It will almost certainly be more reliable and higher speed than your home internet.
you also already have a public IP, assuming your pi's local router has a route to the internet. the router is performing NAT so that devices "behind" it with only internal addresses can still communicate with the world. You can almost certainly configure your router to forward a certain port to your pi's internal IP address.
set up a VPN between the private networks, or between the individual hosts on the private networks. This is a lot of work and will require more knowledge of IP networking. If this interested you, I'd recommend looking at Wireguard (recommended) or OpenVPN.
Finally, keep in mind that unless you do something to make it not the case, your service, once on a public IP, will be accessible from the wide world. Since IPv4 space is pretty small by 2022 standards, and there are only 65000 some IP ports per address, it won't take nefarious parts of the internet long to find your service. You can't hide in the obscurity of an IPv4 network.
If your public address is ipv6 instead, those are essentially unguessable and much more likely to go unnoticed. Same thing is true of ngrok - since it has very large set of potential URLs, it's hard to guess. Still, I'd set up some sort of authentication in front of the service. It's just good practice, like locking your house.
Run this on vps:
echo "GatewayPorts yes" >> /etc/ssh/sshd_config
And this on your raspberry pi:
ssh -L remote-port:localhost:your-local-port your-vps.com
You will access server using: your-vps.com:remote-port
I am struggeling to connect to my home server that is connected via a Fritzbox router to the internet. I want to connect to the home server from outside of the home net, as it serves as a NAS and provides HTTP(S) services.
The problem is, that I don't understand how to connect to the server over the internet. My Fritzbox is connected to my internet provider via DS-Lite internet connection. As far as I understood, this means that my Fritzbox has no public IPv4 address and therefore the server is not reachable.
Is it still somehow possible to connect to the server?
Reading your question, I can see that there are multiple steps to solve this.
figure out if your internet provider allows you to have incoming connections
I do not know, what a ds lite connection is. Depending on your connection type, e.g. glass fibre, dsl, mobile and your provider incoming connections might be allowed or not. Also specific ports might be forbidden.
Enable port forwarding for incoming connections to your lan server.
Your fritzbox does not know, where to route the incoming connection to.
Make your lan server ip address static. Go to your fritzbox admin page and create a port forwarding rule and map data incoming on port 80(HTTP) and 443(HTTPS) to the lan server ip address.
You can read further here: https://en.wikipedia.org/wiki/Port_forwarding
Figure out the fritzbox's public ip address by checking out this website from within your lan. https://whatismyipaddress.com/
Connect to your server via http(s)://publicip
setup dynamic dns to have a public domain, which you can use instead of the ip address.
Usually private customer internet connections use dynamic ip addresses. So your ip address changes regularly. This is annoying, because you need to lookup the ip address before you can connect again. To avoid this issue, you can use a dynamic dns provider to give you a domain name, which you can use instead of the public ip address. Your fritzbox should have this kind of functionality already. If not, you can also configure it on your server with a cron job.
You can read further here: https://en.wikipedia.org/wiki/Dynamic_DNS
This provider is easy to use and for free: https://freedns.afraid.org/
use the dynamic dns domain name instead othe public to access your server from anywhere
Be aware, that having open connections to your local network gives attack surface from the public internet. So people might steal or delete data on your server or abuse it in other ways.
I'm serving an app that I want to be accessible from different devices in the same network. From what I've seen, I can do that by accessing the server's private IP. But the other devices have no way of knowing that. Is there a way to setup something like an internal domain?
For the purposes of this answer I'll refer to HTTP as the protocol, which is by far the widest and most frequently used. If it's something else, the principles are the same.
The first option to consider is 'just' using the IP address. https://192.168.0.3/ isn't so bad to remember; IPv6 is worse, being longer. You could email, chat, or otherwise link your users to the address so you wouldn't have to remember it. Most home networks use DHCP by default, but usually give the same address to the same MAC address unless there's so much device turnover that the ip pool is depleted, so the addresses rarely change in practice. Additionally, most routers leave IP space that is not part of the DHCP pool and you can statically configure that on your server to take any IP changes out of the equation.
The appeal of the IP address method is that it's low investment. It's ready to work now. The downside is that if your IP address does change, your clients now can't reach the service as currently configured. Enter DNS. DNS comes into the equation when the DHCP-provided DNS servers are used by clients to query for the record of names such as stackoverflow.com.
The DNS servers on a home network are usually ones provided by the ISP (or hopefully, because ISPs are typically bad at providing good DNS, you'd point at cloudflare (1.1.1.1) or Google (8.8.8.8, 8.8.4.4) or some other decent DNS provider for public DNS. Either way, the point is, your currently configured DNS servers are probably not able to be configured to serve records of your devising.
That leaves you with 4 options: public DNS, private DNS server, "borrowed" DNS domains, or /etc/hosts.
Public DNS can serve a private IP address, and this is probably the next easiest solution. You'll have to pay to register a domain and buy dns hosting (many dns registrars provide dns service for free). You can then own a name like myhouse.net and add an "A" (address) record for app.myhouse.net with a value of your local IP address. Any public query for the name will look up to your internal IP address, but that's not much of a disclosure (they knew you were on one of the RFC 1918 address spaces) and they could spearfish and xss you just as easily with a domain name, so for home use, I'd call publishing a private ipv4 address to public DNS can essentially be done with impunity. Note these address spaces are non routable - they can't be accessed from the internet and conflict with many other folks' home network IP space as well.
Private DNS. As we've discussed, you probably don't have a DNS server in your network, or you wouldn't be asking this question. You're using public DNS servers for resolution. So there's nowhere for you to define a domain and records like app.myhouse.local. The first step to private DNS would be to create or acquire a server which you can provide via DHCP to your local clients, and can be configured with your private domain records. This server would be configured to also do public queries recursively, so it could be used for all DNS traffic on the network. This way, you get to "invent" your own "private" domain that's not part of public knowledge. This is obviously heavy touch. You might be able to find some sort of service that would allow you to do a thing like this online, otherwise you'll need to install software like Bind or equivalent. On the plus side, it's free, and knowing more about DNS is always a good investment.
"Borowed" DNS - by this I refer to services like https://www.noip.com/ which will allow you to create a host record under one of their domains. They often also include software and an API by means of which you can update the record to point to your dynamic IP address. I do not know whether you could store a private IP address in these services. The domain name would be one of theirs, not one of your choosing (something like myhouse.noip.com) But they're often cheap or free, and they do solve the immediate problem of creating a DNS record. Again, the record would be a private address in public dns and could be queried from anywhere in the world.
/etc/hosts: this file (which also exists in windows, interestingly enough) provides a local system an alternative name resolution system to DNS. It typically takes precedence over DNS (ie it's checked first) and could be used to define a record on most of your hosts. I don't know how you'd do it on tablets or phones, and it's obviously something you'd have to set up in advance - not a great fit for your use case.
Looking at these options, I'd recommend you consider one of the borrowed dns domain providers first. IF that seems good, you're done. If you can't justify putting your private IP address into public DNS, that will force you to go that route. Maybe just using the IP address will work fine.
Good day to all,
I am trying to study networking basics. Watched a ton of videos, researched abit and understood better. However I can't find answers to what I am curious about. Forgive me, I am just a beginner in this IT thing.
A computer has a Public IP address (which is sensitive), and obtains a Private IP address after it is connected to a router.
A router has a Public IP address and also a Private IP address (192.168.1.1 for linksys). It will then assign all the devices connnected to it which its own Private IP address, for example 192.168.1.102.
So here is something I don't quite understand (even after researching online);
Mobile phones uses its own public ip address to connect to the internet via Mobile Data, is that right?
Desktop does not uses its public address at all since it is always connected to a router which assigns it a private ip address?
When a computer outside the network wants to connect to a computer inside a network, does the connection happen directly between computer to computer or does it have to connect through the router where the router will then pass the connection to the computer inside the network?
I can't seem to find any explanation how computer IP public address are utilised since it is always connected to a router where it has its own private IP address.
Forgive me, I am just a beginner. Thank you in advance.
1.) Yes(Mobile Phones are connected via radio masts which are provided by your provider.)
2.) Yes, Desktop Computers same as Mobile Phones which are connected to the router via wifi use the routers IP Adress.
3.) If a computer outside the networks needs data from a computer inside your network it sends a request to your router which forwards it to your computer (which request are forwarded determines the firewall of your router). Also if you request data from a computer outside your network you send a request to your router and the router sends a request to the network of the other computer.
I need to access the internet and a completely separate private network from a single Windows 7 computer. Each network is connected to my computer with its own network interface card.
The private network uses the '10.0.0.0' address space and provides its own DNS services. This network is not connected to the Internet and I do not want to connect it to the Internet in a way, other than being able to access both from my computer.
Basic routing is not that big deal. The problem is that no one wants to have to deal with IP addresses to get everywhere.
My default gateway points to the Internet and the default gateway is blank on the network interface for my private network.
My DNS server points to the Internet.
The show stopper at this point is figuring out a way to have my system use the DNS server on my private network for the DNS suffix used on my private network and still allow everything else to go out on the Internet.
Is there any way to make this work?
Bob
In the properties of the network interface card connected to the private LAN have you gone into the TCP properties and set a search domain and DNS server under the DNS tab? If you only need to hit a few hosts on the private LAN host file entries are also an option.