I have build a node js code for an API server. Part of one feature is that when it starts, it should be able to know its own IP, despite the type of setup of the server where it is running.
The classic scenario is not that hard (I think). There are several options, like using the os module and find the ip or the external interface. I am sure there are other ways and some might be better, but this is the way I have been doing it so far. Feel free to add alternatives as informative as possible.
There is this case that I stumbled on. In one case, the web server was running on a google cloud instance. This instance has two IPs, one internal and one external. What I want is the external IP. However, when I use the method above, the actual external IP is not part of the object returned. The internal IP is declared as being considered as non-internal. Even when I run different commands from within the server command line, the only IP returned is the one that is actually internal and cannot be used to access the node server.
From what I understand, the instance itself is not aware of it's external IP. There might be a dns (I think) that redirects requests made to the external IP towards the correct instance.
While reading in the internet I read that problems getting the server's correct external IP might also rise when using load balancing or proxies.
The solution I thought about is to have the node js code make a request towards a service that I will build. This service will treat the node js servers as clients, and will return their external IPs. From experiments that I have done, the req object contains among others the information of the client's IP. So I should check first req.connection.remoteAddress and then the first element of req.headers['x-forwarded-for']. Ideally the server would make a request towards itself, but
I know there are external API like https://api.ipify.org?format=json that do just that - return the actual IP. But I would very much like to have the node js servers independent of services I cannot control.
However, I really am hoping that there are better solutions out there than making a request from the server which returns the server IP.
However, I really am hoping that there are better solutions out there
than making a request from the server which returns the server IP.
It is not really possible, you always rely on some kind of external observer / external request.
While reading in the internet I read that problems getting the
server's correct external IP might also rise when using load balancing
or proxies.
This is because not in all scenarios your own device is able to be self-aware of its external ip. There might be sitting behind some network, that means external address assigned to devices that forwards the WAN to it. (example : router) so when you try to obtain external ip from the devices interface itself, you end up obtaining an ip but inside the scope of the routers LAN and not the one used for external requests .
So if you really want to
Have a method to use in all scenarios
Not rely on 3rd party services
Only Solution :
Build your own ip echo service (you maintain and can use for future projects).
Related
I have a ReactJS web app that runs on a local network, but is also accessible via a DMZ'd address to a larger local network. The backend is a node server on that LAN, and I realized it will also have to be exposed so browsers on the broader network can get at it.
What is a good way of handling IP addresses depending on which network the user is on dynamically? Users in the LAN would have to have their browsers aimed at 192.168.x.x, say, while broader network users would have to point at 10.72.x.x, as an example, and I don't have a good idea of how to handle this on the fly.
EDIT: I can use something like ip to check my subnet and adjust accordingly, I suppose...not sure this is a best practice.
EDIT 2: I think that maybe I'm not being clear enough from the comments, so here's a little more info:
From the LAN perspective, I need the browser to hit the server at 192.168.25.31, say. And from the DMZ perspective, I need the browser to hit the server at its broader address, 10.72.10.31, for example. The two addresses are known, and static. What I need to be able to do in React is select the correct one of the two based on which subnet said browser is on.
I have few APIs implemented on one remote node server and I want to make requests to that server through my web page, but is it the case that browser / anti-virus s/w will consider requests made to direct IP address as dangerous and might block them entirely ?
Is it necessary to assign a domain name to that remote node server ?.
Whilst I don't think an antivirus would stop a program making requests to a server simply because the request was made out to an IP address, this is generally not the best practise. You should use a domain name, or subdomain for your server. This helps identify the server and in the case that the IP address of the server should change, the application does not need to be updated because DNS will do the bulk of the work next time the application attempts a connection.
TLDR: It will work, but it's not a good idea.
They can and they do. In the end of 2017 when several webminers such as coinhive become popular some anti-viruses started to block the websockets connections directly, even if the miner tries to connect using only the ip address.
It's not necessary to assign a domain name to your server, but you won't bypass anti-viruses that way.
I'm using node js trying to send my web-page to my network, I successfully call localhost:port in my computer using express as server, the webpage loads fine trigger my webcam which I used to streaming in the webpage, and then im working to make a simple app in my phone to directly access my server, so my questions:
1.How do I able to access my server from different devices in the same wireless-network? by calling ip + port ?192.168.1.104:9001 ? cause i've tried and it didnt work.
2.I've found https with .pem something like that, is that the answer ? is there also any other way ?
3.maybe any advice before i work to make my web-app to devices? using koa? i don't even really know what is that, but i'm happily take any advices.
EDIT: i've read How could others, on a local network, access my NodeJS app while it's running on my machine?
let's say I simply using random router, so i can't configure my router-port, my server in my pc and my phone join in the same network, trying to access the server in my phone
1.How do I able to access my server from different devices in the same wireless-network?
All you need to do is find your server's IP address in this same wireless-network, and find the Node.js application's port. Then access the following URL in other devices:
http://{server_IP}:{port}
However, there are some points need to check:
Need to check firewall and confirm the port is not blocked, server IP is not blocked by test device, and test device IP is not blocked by server.
Need to check whether there is any Proxy setting in server and test device. If there is any, disable the proxy.
A computer may have many IP addresses at the same time, you need to find the correct one in the same wireless-network. For example, If you install a virtual machine software such as VMware and run a virtual system inside, your real computer will get IP address as 192.168.*.* -- this IP address looks like an intranet IP in wireless-network, but it is not, and can never be accessed by test device.
2.I've found https with .pem something like that, is that the answer?
No, HTTPS has nothing to do with this problem. HTTPS just add security (based on HTTP layer), it does not impact any HTTP connectivity. Actually, to minify the problem, it is better to only use HTTP in your scenario.
There is only one very special case that may bring your problem by HTTPS -- the test machine is configured and will block any non-HTTPS connection for security.
3.maybe any advice before i work to make my web-app to devices? using koa?
My suggestion is: As there is an HTTP connectivity issue, the first step is trying to find the root cause of that issue. Thus, it is better to make a simplest HTTP server using native Node.js, no Koa, no Express. In this way, the complexity of server will be reduced, which makes root cause investigation easier.
After the HTTP connectivity issue is fixed, you can pick up Koa or Express or any other mature Node.js web framework to help the web-app work.
4.let's say I simply using random router, so i can't...
Do you mean your server get dynamic IP address by DHCP? As long as the IP is not blocked by test device, it does not matter.
So I am currently working on a destination based routing setup, and I'm really new to the world of Linux. I'm mainly trying to get this to work for video, so what I want to do is route any traffic that I specify through my vpn, and keep the rest of the traffic local. I tried to do this with BBC iPlayer, and I ended up reaching a roadblock because nslookup did not yield the server addresses for Akamai, BBC's CDN. I used tcptrack to find all the incoming connections onto my machine, and I sorted it by connection rate, and the top few would end up being the akamai servers. Well, once I figured this out, I am currently trying to automate the process, and I cannot get tcptrack to write to an output file. Does anyone know of a way to get tcptrack to write to a text file or know of a program that would be better suited to my purpose? What I currently do is use the route command and route the server address, both the one that tcptrack gets me and the nslookup address, through to my vpn using the syntax route add (server address) dev tun0. Any help would be appreciated!
Not sure if i understand the context correctly but if you want to direct specific traffic say based on client IP or domain name then this is possible using Akamai.
Can two or more domains be hosted on the same server? If yes what is the ip address we are going to get for the two domains?
as a user can i know how a server resolves the host name and assign unique id to different host names
After looking at my comment above and as you are a user, not an administrator, just look at the documentation of nslookup(1). It is a tool to make DNS queries to servers. It allow you to make dns resolution and to investigate the ways you are getting the answer (there are many ways to answer a query, believe me)
First you need to know how the asking is being done. Normally, clients make recursive queries (they want definitive answers to a query and want the server to do the heavy work) and servers do iterative ones (they approximate the answer by asking the servers in the chain to the final domain you are looking for) Servers and clients normally cache results for future questions and provide several ways of fault tolerance, so you cannot control normally how a query is solved. As this is probably the most requested service in internet, the protocol has been optimized to get quick answers even in the worst case.
Once you get an answer, it can be a partial one, it can be cached, it can be non-authoritative (meaning the server is serving a cached entry, not a locally administered one)
When you have several responses to a query (ok, this can happen) you receive them normally in order, depending where are you querying from. The server makes a best effort to order them on proximity to the client (the nearest address is served first) and/or randomly ordered, so you can make round robing to each of the addresses you receive. It depends on the client software, the server implementation, the administrator policy, etc.
Even you can receive a different response depending on who you are. Several corporate servers serve different views of the database depending on where the clients come from. If they come from the inside of the company, they serve addresses for servers not visible from the outside. For example, if you try to access the corporate web server, you can receive the private address to reach it, not the public address of the server accesible from the internet. This concept is called view, and many servers implement it, so the answer to your question is: it depends :)