I have a node express server running on Machine 1 as (0.0.0.0) and some client applications running on Machine 2, 3, and so on...
All machines are connected to the same Wi-Fi
How can I get the private IP of Machine 1 (which is running the express server), so that I can directly start calling the server APIs from client applications?
Note : I am using electron js in both server and client
There are a couple possibilities.
You can assign a local IP address to your server that does not change and thus is known. For example, on my LAN, I configure the auto-IP assignment to avoid 192.168.1.200 - 192.168.1.255 and thus I can manually assign those IP addresses to devices for which I want to have a constant and known IP address. Then, you can just refer to the "known" local IP address from your clients as in http://192.168.1.201/somePath.
You can configure local DNS (probably in your gateway router) so you can access your private server from your private LAN using a DNS name and combine this with option 1 so the IP address of your server won't change. You will need a router with this capability.
You can use a resource discovery service such as Simple Service Discovery Protocol (built into Windows) or BonJour (built into MacOS, available for Windows) if your client has the capability to use these. Your server will advertise its services in the resource discovery system and the clients can query the system to find the server.
The short answer is that you can't. HTTP servers don't broadcast their addresses.
You need to run some other kind of service (on the same machine as the HTTP server) such as zeroconf to provide discovery.
Then you need the clients to use it to find the server. You're probably out of luck if your clients are written in browser-side JS and you'll need to go to another level of complexity. I think DNS-SD is the way forward there.
Related
i wanna use node js on my webpage, which is hosted by a company. I saw that you can run a local server on node js, but does anyone know how i can link it to my existing domain example.com.
As mentioned I saw that you can use express for this, but i dont know my port neither how my server reacts to my js code.
any recommendations?
To be able to access your locally developed node project from your domain name from any computer connected to the internet you will need to do something like the following:
Point your domain's DNS records to your server
Log into your domain name provider and find the DNS settings section, then paste in your servers IP address. Once this is done, visiting your domain name in the browser will connect the domain to your server which you control. Under the hood the browser can now successfully ask the domain name server (keeps records of domains and associated IP addresses) for the IP address to query which corresponds to your domain name. But thats not quite enough yet!
Install a server application on your server
A server is just a normal computer with server software installed which enables incoming requests to receive a response in anyway you define in the configuration of the server software. nginx, apache and express are all types of server software.
At this point you need to see whether the server you are renting supports nodejs as a server, if not you should look elsewhere for a provider that does. (not hard to find)
Install software dependencies to get your express server up and running.
EG:
node, npm, express
Recently i've been choosen as backend lider for course on my studies. We are suppossed to write BE for chat app that will allow users to communicate p2p without any server code (i know it means that there's no BE, but my proffessor isn't technical person). I've asked him if it could use webrtc, but he didn't like the idea of using STUN and TURN servers. So my main question is, is this possible at all? We are talking about an app that will run in browser, not directly in OS. And if it is, what protocols/apis can we use to achieve that?
I am not sure if I get your question right, so here are some general informations:
WebRTC as a P2P API relies heavily on servers.
"ICE":
To connect one Peer to the other Peer, the peers need to know their IP address to exchange data. They can "ask" their OS for the registered IP, but this will only yield 127.0.0.1 and their local Network IP. This works for connections on the same computer or between computers in the same local network, but it will fail for everything else.
The ICE Servers STUN and TURN are necessary, since your browser clients are behind your Routers Network Address Translation (NAT). STUN gets the NATs IP Address and Port and TURN forwards Packets as a known, public IP Address if STUN fails.
"Signaling":
Let's assume, that your Peers know their own reachable IP-Addresses (- probably the NATs IP and Port by using STUN and maybe even TURN). Even IF (!) they know their reachable IP, they have to tell the other Peer that this IP is in fact, their IP and the IP to use to contact them. They also have to tell the other Peer some other technical information to make the transmission of data work. To use WebRTC, you need to have a WebSocket-Server (or a combination of Server-Sent-Events and HTTP Post Messages), which forward this information.
After everything is established (they know their respective IPs and Ports, technical information, etc.), you can then send data over WebRTCs DataChannels.
My Advice:
Do not use WebRTC for the given use case. If you do not want to use a Backend-Server, you have to search for "serverless" Web-Apps. P2P will always rely on some sort of server to start the connection. If you use a "serverless" architecture, someone else is hosting the server / chat service you want to use (also commonly referred as "cloud based"). If it is about hosting costs for a prototype app, you may have a look at heroku.com, aws.amazon.com, zeit.co, firebase.google.com or other hosting providers with free, limited (test) plans.
So a website of mine is hosted on godaddy, now I want to connect it with a server that is running socket.io, and I have some balance on digitalocean. However, I am not sure how I would do this, I think it should be like this for client side?
var socket = io.connect('http://Digital.ocean.ip.here:port');
and then server side like this
http.listen(port, function(){
console.log('listening on *:port');
});
the only thing is that if this is how I am supposed to do it (and it even is possible if it's not the localhost), than users will be able to see the ip of my droplet when they take a look in the source code, and perhaps DDOS it or maybe worse I don't know?
When I see other sites using socket.io for a chat for instance, I never see their IP. Does that mean they host their entire website on a service provider where they are able to use socket.io/node.js?
Any answer will be highly appreciated!
--Edit--
My client wouldn't accept http and therefore I decided to buy a domain and ssl so it would use https.
There's no way to every hide the IP address of a server that a browser connects to. It makes no difference whether the connection to the server is http or socket.io or any other TCP based connection. Anyone can see the IP address. So, that simply isn't something you can protect or should worry about.
In most cases, code will use a DNS host name (not an IP address), but the DNS service itself provides a way to lookup the IP address for a host name so the IP address can be fetched that way. Or, one can just load a debugger or local network snooper and easily see what IP address is being connected to. A host's IP address is simply not a secret.
If you are worried about DDOS, then you will have to implement server-side protection from those types of attacks. You can't do anything in the client to protect from those kinds of attacks.
Is there a way that I can make a GET request from an external server (like google apps script) to my local server?
For example, I would like to make a GET request on this url: http://localhost:3000/api/get_data
If I do that then I get DNS error. Replacing localhost with my ip address gives Bad Request
The "localhost" address is not accessible from the Internet, so you can't use it.
Having your IP instead of "localhost" may work, that depends on the firewall rules of your ISP and on your local machine.
The easy way to expose your local machine to internet is either by using SSH (if you have the remote machine that is accessible from Internet, for example, Amazon EC2 instance). You can use -R ssh switch for that, something like this ssh -R *:8181:localhost:3000 remote-machine and you can use "http://remote-machine:8181" to connect to your app.
See also The Black Magic Of SSH / SSH Can Do That?.
Another way is to use service like https://ngrok.com/ that will do the remote part for you.
I'm using an arduino UNO and an Ethernet Shield to create a web server to response HTTP requests.
The requests are sent by ajax XMLHttpRequest.
It's working fine with static ip address.
But a want the arduindo to get a DHCP ip, so I can use it in any local network (with DHCP).
I want to discover the ip of the arduino connected on the local network.
So I can use it as url to send HTTP requests.
Is it possible to do that in javascript?
OK, thanks for answering my questions above. That helped layout the network structure and the problem you're trying to solve.
Summary of the problem
Two computers: 1 web server whose address is dynamic (DHCP) and 1 web client running AJAX and HTML. How can browser find DHCP server?
Options
This is a classic problem solved many different ways throughout the history of computer networks. I've suggested some options below.
Scan for the server via TCP.
Scan for the server via UDP (requires special browser library).
Run a DNS server.
Have Arduino signal its IP.
Modify your router.
Don't run DHCP - use a static IP.
tl;dr - Use Option 6 if you don't control your router, Option 5 if you do.
Option: Scan for the server
I'm assuming you know your browser machine's IP address (for example, 192.168.1.17). In this case, run through all of the address from 192.168.1.0 through 192.168.1.254 (not .255 and skip you browser machine's IP) testing for a connection to port 80. This will find every web server on your subnet, so be aware you will need a way to recognize your arduino responded to the web request in case some other web server is also listening on the network. It will also take some time to set up, test and wait for timeouts on most (252) of the addresses which don't have web servers. You will eventually find it.
I'm not a fan of this one, but it gets the job done. Warning: if you don't "own" the network, someone may be angry with you for scanning their machines. A company, school or other institution may have policies about not scanning networks.
Option: UDP from the browser
This one is great, but requires a browser plug-in and some fancy coding. UDP allows one to broadcast a message to your subnet (try ping 255.255.255.255 at a command line and watch the machines echo back their IPs). If the arduino is set to listen for UDP packets on a particular port, it can echo back to the sender of the UDP packet and let that user know it's present. This is how DNS, DHCP, ping and Apple's Bonjour work. Many IP based systems advertise services by responding to UDP requests. Clients need not know the address of the servers on the subnet, they discover them through broadcast messages on well-known UDP ports.
Unfortunately, this requires a browser modification because Javascript does not support UDP for security reasons. I understand this and agree with the security restriction. However, it has cut out a really nice feature of dynamic service discovery. If you're on Apple on the browser, you might be able to find a Bonjour emulator you can run on the Arduino and it might work ("arduino.local" might attach). This might be possible with Windows service discovery, too, if you're using a Windows client for your browser. I don't know what's available in Linux for service discovery.
I don't like any of these modifications for you. Browser, Arduino (Apple, Windows or Linux), just because it adds more moving parts and you're counting on the browser to "know" how to find the service.
Option: Run a DNS server
This isn't as bad as it sounds, but I'm not sure the Arduino could handle it. Find a very small DNS server written for the Arduino and have it respond to DNS requests. On the browser, look for a well-known machine name (e.g. "my-arduino.lan"). This essentially finesses the UDP problem above by making the Arduino the UDP server (handles DNS requests) and the browser already has name resolution s/w (like every machine on the planet).
I didn't search for Arduino DNS code, it might be too large for the Arduino and writing it may be a real PITA (pain in the butt).
Option: Arduino signals IP
In this model, you can attach a LCD to the arduino and have it present its IP address on the display. Alternatively, the arduino can send a message (via TCP) to a well known server on the network (internet or otherwise) reporting its IP address there. Your browser can query that server, pick up the IP address and then contact the Arduino directly. This introduces a 3rd machine and acts like your own hacked form of DDNS (look it up, if you're not familiar with it).
Option: Modify the router
If you own the router, you can modify the router to assign a specific IP address to the Arduino, even with DHCP. This is your best bet. Here, you control the network, can allow the Arduino to come up in DHCP while still fixing its IP address. You'll have to go through your router API (web or CLI) and figure out how to do it, it's a bit hard directing you as there are thousands of types of commercial and SOHO routers.
If you don't control the router...
Option: Use Static IP
This option is really your best. Give up on DHCP and just set the static IP of the arduino. Just make sure the IP address you pick doesn't conflict with any other servers on the subnet. That shouldn't be difficult.
I hope this helps.
The 2 best options I think:
1) When arduino starts, gets an IP address from DHCP, arduino should make a connection to a well know service provided by you. Also, each device should have an ID, defined by you during manufacturing, like mac address or part of mac address.
So, you can print on the box something like: 5c4e6f.my-well-know-host.com
Than, as I was suggesting, each time arduino starts, it tries to connect to that service passing parameters like:
POST www.my-well-know-host.com
ID: 5c4e6f
IP: 192.168.1.55
than, at that service, you update a DNS table to reflect this relation:
5c4e6f.my-well-know-host.com -> resolves to 192.168.1.55
obviously, from anywhere in the world the host 5c4e6f.my-well-know-host.com will resolve to 192.168.1.55, but you will only access it from you local network.
Tip: this is some kind of DDNS, but with network discovery purposes.
Tip2: there is an linux dns service called MyDNS, where the hosts are simply records inside a MySQL table, easy to maintain.
2) Network discovery
I don't know if arduino is capable to do it, but, the idea is to make arduino listen on a specific UDP port, like 4444, on any address.
So, you can build a windows app, and Android APP (I already made one android discovery for another purpose, not arduino), or, the best solution that I still researching on, is to make a custom page with some javascript code, that "looks" for devices listening on that specific port.
Works like that:
Device gets IP from DHCP
device starts a thread listening for broadcast packets on port 4444
a discovery app listen on another port, like 4445.
the discovery app announces itself using a broadcast packet to 4444 port (255.255.255.255:4444)
each device listening, reports back with its identification and IP to app port 4445.
This is a code to find the server ip:
<script type="text/javascript">
var ip = "<?php echo $_SERVER['SERVER_ADDR']; ?>";
alert(ip);
</script>
If you are using Johnny Five framework, then you can find APIs in that framework