This may be a strange question but I really want to learn how "ping" command works. Today when I had my smartphone open and online, I pinged its external(public) IP from my terminal in Linux with "ping [ip address]" command and it worked of course.
When I turned off my smartphone and retried to ping its IP, it worked again! As far as I know ping is like sending a message and then getting a reply from the target.How is this possible since my phone is offline?
Any explanation is much appreciated! Thanks!
UPDATE:
Both my phone and PC use Wifi to connect to the internet and are in the same network.
Also there was not any other device that joined the network when I tried the above.
If you subscribe the service from an ISP, then you might share the use of one public IP address among your devices to connect to the Internet. Internally you'll use private IP addresses for your PC and phone. It seems to me that what you have pinged was the public IP address assigned on the gateway of your wifi router and not your phone.
If you are not sure, then try to access http://whatismyipaddress.com/ from both your devices and see if you have the same IP address or not.
Related
Currently my program use the IP of the other device in order to communicate over grpc.
Unfortunately the IP is changing all the time and I cannot continue the connection between the devices without updating it manually.
The connection between the devices is only on LAN and should blocked access from WAN.
Locking the IP of the device in the rowter settings is not an option this time.
Does grpc have a way to communicate over LAN (inside my network) using identification number or mac address that does not change over time?.
Related questions I found:
grpc: Identify clients from same IP address
Reason for both a MAC and an IP address
In order to locate a machine based on its MAC address, you are talking about implementing ARP. This is something that is not supported in dart nor am I sure it would be advisable to go this route anyway. If setting a DHCP reservation on your router is not an option, are you able to skip DHCP and set a static IP on the receiving machine?
You could look into dynamic DNS which your router may support, or you may need to set up separately, but that will also require a static IP (for your DDNS server). If your machines can connect to the internet there are many DDNS services you can sign up for, but it sounds like that is not the case.
I'd like to know that a specific device (phone/tablet) has joined my WiFi network created by ESP8266 microcontroller. It shouldn't require any installed apps on that phone/tablet, if possible, to simplify the whole setup.
So I think I need to somehow identify connected clients, and MAC is not an option because it is subject to change randomly on, say, Apple devices.
Maybe it's possible to collect host names of connected clients?
I know that Windows and Ubuntu clients send their host names when getting IP from DHCP server (see here). Also, it's possible to find such information on, say, home Wi-Fi router admin web page (i.e. host names, their IPs and MACs).
I'm running DHCP server on ESP8266, but I haven't found any API that allows to get peer host name (i.e. reverse DNS). Does ESP8266 support getting such information?
I want to scan for all devices in the local network. Then I want to further check if the discovered devices respond on a specific port, say #4000 for example. All that should happen on an iPad preferably using Swift (version 3).
Should I use a library for that job?
This document didn't help me and sadly I cannot find useful information on the internet.
Edit: I want to know how can you implement this in Swift/iOS libraries. Are there any examples, libraries, core classes where I should start?
I think I may know what you are trying to ask. Your device sees the router, but doesn't know who is connected.
Read about multicast IP and broadcast IP, which is usually the highest IP address in your subnet.
Example: 192.168.1.255
As example, you make all devices listen on broadcast/multicast IP. To discover, you send a UDP message to that IP. Your router, if not configured otherwise, will forward that to the other devices.
This message can be something like "I am Mr. John, Reply to me at this Port".
That is the general idea
I have implemented a web service on my mac and I am able to access its functionalities through the url "http://localhost:8080/ServiceApp-war/resources/".
As I got satisfying results that I could see in the iPhone simulator in Xcode, I decided to connect my iPhone and test on it. But for this to work I think I need to change the "localhost" in my URL to the IP address of my mac.
I tried to replace it with my public IP address and I got a "could not connect to the server" error on my console. I also tried to replace "localhost" with the IP address I found in System Preferences-->Network-->Wi-Fi and I could see that it was working on the simulator but still nothing when I connect my iPhone and run the application on it.
Please provide a solution for accessing my web service remotely.
Thank you.
Create hotspot from your mac, connect to it with your iPhone and try again.
<lame solution>
Try some service for temporary domain, it will make your computer accessible from anywhere.
How do you "connect" your iPhone? USB connection does not create a network. Well, it does create if you turn on Personal Hotspot on your iPhone (maybe in some other cases, dunno). But the most simple way is to connect Mac and iPhone to the same WiFi network.
Once connected, you can use any of "ping" apps available on App Store. Just look for "ping" (some kind of "network reachability test" or so). You can check if your Mac is really reachable on the network.
If it's not reachable, check your network settings on both devices: do they belong to the same subnet, do they use the same gateway, etc.
If your Mac is reachable with ping, then you should deal with your web service. I setup the web server (which is already distributed within OS X): it already has all the settings to allow other devices to connect. But your web service may require some additional setup. It's two basic things: it should bind to your IP address (please check http://YOUR.IP:8080/ServiceApp-war/resources/ from your Mac!) and second, accept incoming connections from other agents, you should find it somewhere in its settings.
Ngrok was the perfect solution I was looking for.
https://ngrok.com
You could also try finch, which is similar to ngrok. It has a nice friendly GUI. https://meetfinch.com
I have ip addresses of two different iOS Devices which are connected to Internet. Now, I want to establish a peer-to-peer connection between them.
I had done this locally with Wifi and it worked properly. But I dont know how to establish this connection with an IP address. I want that I can connect them from anywhere, so I need to connect via Ip address. Also, is this possible without developing any server? Please help. Thanks.
I couldn't find any exact solution for this problem but one approach could be you can have two ios devices connected with a network having same public IP.
So indirectly both ios devices will be connected to the same network.
What you had done with wifi is probably an Ad-Hoc connection. Ad-Hoc is when you connect 2 wifi devices without any Access Point in the between.
You do not have to do that on the Internet, your devices are already connected to a network. What you need to do is to find out what their IP addresses are and provide them to eachother.
In case your iOS devices are NATed behind a router, you must forward the port which you want to use from the router to the iOS device.
Here are guides for port forwarding for all the existing routers: http://portforward.com/