I have Raspberry Pi and a mobile app developed in ionic.It has to communicate over SocketIO and normal HTTP request. I can communicate if i know IP address and port no. But what if I'm using it over internet and my raspberry pi's IP address is changing dynamically due to DHCP. How do i connect to my raspberry Pi device. Is their a way to connect if I know MAC address of Rasspberry PI.
Short Answer: no
Slightly Longer:
MAC is only useful at Layer 2. So the minute you have a router between you and the device, you will no longer be able to see the MAC. If you control the Layer 2 network you can statically assign a DHCP address, or you can look at the logs and see what IP it was assigned, but if the device is connecting to networks you don't control and its address is changing, you will need a way for the Raspberry Pi to register where it currently lives. There are a variety of ways to do this, such as dynamic dns registration, or you could have it phone home to some sort of locator service that your app could then query, etc... But without extra software you are probably out of luck.
You should use a dynamic IP service like www.noip.com. They provide a free linux and/or windows client.
That way, when your public IP changes, you will still be able to connect.
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I created two Qt apps: one client and one server.
I use them to send some data for handle a remote device.
If I am in localhost I haven't issues about them, but when i search to connect them by internet i don't know how to find correct Ip server to connect Socket Client.
How i can find this ip node?
Is there a class to find It?
you cannot find it automatically, if this is what you're asking about.
In real life you would deploy your server on some publicly accessible host, give it a domain name (important part as your host can change the IP address at any time) and connect the client via the DNS domain.
However if you're just playing around and you want to show to the world that your app works, specifying the IP address of the server in your client code would be perfectly fine (assuming you're running both the server and the client in the same network).
In that case, if you're running mac/linux run the command ifconfig (or just ip depending on the distribution). On Windows you can run the command ipconfig. Both windows and linux will give you a similar output resembling this:
Pay attention to the network adapters. There can potentially be many of them. You may have some emulated adapters if you have docker or VMWare, you may have the wireless adapters if you have a WiFi card, and then the ethernet adapters if your computer can connect to the the internet with an ethernet cable. Each of these adapters specifies a different IPv4 address. You want to pick the one that is connected to the same network as your client. So for instance if both your server machine and your client running machine are connected to the same wifi, you pick the address from the Wireless LAN adapter
I have a router (belkin) with many devices connected.
I ran a application on one my devices and the application assigned a port number for remote connection.
Now for me access this device i tried doing something like:
wanipaddress:port
But unable to connect. I am not sure if the router can be used to accomplish the above.
Any suggestions on how to achieve the above?
P.S my router assigned unique LAN IP to all the devices.
I achieved the following using Port Forwarding mechanism. A port forward is a way of making a computer on your home or business network accessible to computers on the internet, even though they are behind a router.
I found the following tutorial to be useful:
I have been looking for an answer to this problem, but I cannot find what I am looking for. I think, perhaps, it is because I lack the knowledge to ask the question in meaningful way.
I have been learning a lot about remote access to devices at home. I know that ISP's change public IP addresses regularly (dynamic IP address). I know that to get around this, one could use a service like "no-ip", etc. Or one could get a static IP address.
What I do not understand is how some of the latest home automation devices are able to be controlled remotely without use of a static IP, or a service like "no-ip". For example, a wifi enabled thermostat, or lighting system.
If the device had a built in server, or client, then I assume that the device could connect to an outside server in a remote location. The user could then also log into that server and send commands to the device. What I don't understand is how commands sent to the device from a cell phone, for example, can reach the home device. Presumably the off site location of the server would have to know the public IP address where the devise is located, and then port-forwarding would have to be set up to allow access to the device.
What am I missing here? Is it possible to create a homemade wifi enabled thermostat, webcam, or other device without using port-forwarding, no-ip, or a static IP?
Well, there are several ways to bypass the inbound connection constraint of NAT protocol. Such as:
A virtual adapter on the device configured to a VPN server that has an inbound port open ready to transfer data. Various open source solutions such as openVPN are considered as great examples for this service over IOT boards like Raspberry Pi, Beagle Bone, etc. These are used as gateways often. Further, they communicate with the microcontrollers over popular IOT protocols such as MQTT, COAP, etc.
Another solution is to create a port forwarding tunnel, since the router won't block the outbound connection. There are various tunneling services that are availble such as localtunnel, ngrok, etc. You could also use a cloud server that has a public IP such as AWS, DigitalOcean, etc. Again as above mentioned point, they can be implemented in the gateways.
Some devices "phone home" to a server so that there are ports open between them and the servers, and the mobile apps just contact the servers. This is the same way your web browser can receive web pages from a web server. If you have a NAT router, the router must open a port from the inside device to the outside server. This is maintained in a NAT table with expiration timers for UDP and session monitoring for TCP.
I want to develop an Android app that connects with a Windows desktop application via TCP/IP.
However I have very little knowledge of networking and so please forgive me if this is a very basic doubt.
My Windows based laptop as well as Android phone are connected to the internet via the same WiFi router.
Now I checked the IP address for my laptop as well as phone using a website.
Both are same!
If both have the same IP address, then to achieve networking between these devices I will choose different set of port numbers.
Will this connection work?
Is the connection happening via the internet or just locally on my
router?
EDIT: After reading the answer from #Doon, I have broadened my question.
Let's say the local address of laptop is 192.168.1.10 and that of phone is 192.168.1.20.
If I code my application to use these IP addresses, it should work as it is a local network.
But what if I want my laptop to connect with another phone which is not connected to the WiFi router, rather by 3G network.
Then which IP address should be used for the laptop and the other phone?
Since I am not allowed to use any other server, I am going to use port forwarding i.e. the user will type in the IP address displayed on the other device. The connection could be initiated on either one of the devices.
If you could also show how to do this programmatically, it would be very helpful.
My Windows application is developed in C++ using Qt.
All of your devices are sharing 1 external or WAN IP address using NAPT (network address port translation). Internally on your LAN each device has its own address. So yes it will work but you are going to need to use internal addrss and the devices actual IP address not its perceived address via an external service.
As for the connection locally or via router that all depends on where you are connecting to. If both end points are on your lan or on the same Subnet then the router will not be involved. So in the average home network between your phone and desktop both connected to the same network say via wifi then they are most likely layer 2 adjacent (see the OSI 7 layer model for more info on layer 2 vs layer 3). But once they are not on the same network then routing will be involved and your router will be used. If the phone is connected to 3G or the cell data network and you want it to talk to your desktop on your home network you are going to need to deal with port forwarding on your router and other such fun things.
In regards to updates. Once you leave the local network it gets more complicated especially with IPv4 as address are running out so there is more and more use of nat or IPv6 with 6 to 4 gateways. Do you want the laptop to initiate connect to the phone or phone to the laptop? But normally you will need to iterate your address on your interfaces. Then connect with an external service to get your external IP address and compare and see if they are the same. if both endpoints are dynamically assigned you will need some sort of location mechanism could be dynamic DNS could be locator service etc.
My goal is to have two laptops in a network. One is acting as a server, serving webpages to the other. The catch here is that neither is connected to the outside internet.
What I have done so far is setup WAMP on the server laptop, and it successfully serves web pages on localhost. Now I want to access these pages on the other laptop.
To do this, I had the server create an ad-hoc network and connected the other laptop to it, but I'm stuck - and I'm worried I'm not on the right track. I followed this tutorial but in the end I figured out that just explained how to spoof a text URL as an IP address, and not really what I was looking for.
So I guess I have two questions:
Is my method the best way to do this (with ad-hoc networks)? Is there some way to connect a laptop to a wireless router and have the laptop act as a server to another laptop?
If my WAMP and ad-hoc network should work, how do I connect other laptops to my server through the ad-hoc network?
Thanks!
I would suggest the first option: get a wifi router. Then you can assign static IP adresses from the routers private network or use DHCP server on the router. Hopefully you will have an option to reserve IP adresses on DHCP server so you dont have to check every time what IP adress the laptop acting as a server got. You use this address to access your web server. Also, you can use this router later as a gateway to the internet if you want.
In ad hoc mode you will probably get an address from 169.254.0.0/16 link-local scope, and you can check it by running ipconfig as #Robadob already suggested.
On your hosting laptop open cmd and call ipconfig look for the internal IP address on the network interface your hosting the ad-hoc network.
Enter that IP address into the browser on your client laptops web browser instead of localhost.
If that doesn't work, try other ip addresses listed by ipconfig (incase you used the wrong) and then check the properties of your ad-hoc network, windows firewall and any other firewall software to disable anything that might be blocking it.
An ad-hoc network is suitable option for what your doing, most people would probably use a switch or router though, however that requires hardware you probably don't have.