For the project I'm working on, I need to directly call the IP address of a computer within our C# environment. We are using asp.net / mvc 3 and the customer facing website has a controller that will expose an endpoint to hit from within the admin area of the site. This controller action will then call another private internal ip address that actually does the ground work. Basically there are two machines, one is customer facing, and the other machine is more for setup.
<private_ip_address>/admin/do_something_private
Does C# have a direct way to call an IP address like this?
As long as the PCs can see each other you can always establish a communication between them via HTTP. Just make sure you know how the endpoint is configured and what kind of "requests" it understands. Yet, the client must be aware of any security implementation on the server side in order to successfully authenticate the request. That's as abstract as I can get provided that your question is way too abstract
Your internal machine will have an external IP address. You'll need to point your external
L website to the external IP address of your modem/router and use your modem/router to route the request to the internal IP address. You can also put your internal machine on your router's DMZ but that's usually a bad idea.
Related
I'm using Owin and Topshelf to selfhost an ASP.net Web Api.
I am able to access it through localhost and 127.0.0.1 on the device that is self hosting it.
The idea is that any device that comes onto the network and has my computer or mobile application installed is able to communicate with that web api to request/update/remove data from the database hanging behind.
The issue i am having is that i have no way of finding out on what internal ip the service is actually running. I have no control/view over the network that it's installed onto (except through my code), this means i don't know what the ip or hostname might be, only the port number (on any other device that isn't hosting it).
I tried adding custom url's like shown below
StartOptions options = new StartOptions();
options.Urls.Add("http://localhost:6969");
options.Urls.Add("http://127.0.0.1:6969");
options.Urls.Add(string.Format("http://{0}:6969", Environment.MachineName));
options.Urls.Add("http://+:6969");
Obviously localhost and 127.0.0.1 won't work for a remote device on the same network. The issue with the MachineName is that i don't have a say in the name of the machine either, meaning this could be anything. I assumued the wildcard would allow me to send a request on port 6969 and the host would catch it, this was sadly not the case.
This leaves me in a bit of an issue, i now have a self hosted Web api, on a machine with a random ip and name, and it needs to be accessed by other devices on the same network, The users are not able to manually enter ip, and i can't force a name onto the host computer. This all leaves me in a situation where im not sure wat else i could try, or if its even possible to reach the host computer without human interference.
Edit: I did come across something along the lines of a
network broadcast address
Which should in someway allow me to send out a message from a device, and let the server respond with its ip. Not sure how i would apply this to my self hosted web api though.
Basically, the idea is to have your web API application register its address to a service, such as DNS, which may be updating the IP address of a DNS A record. Then clients will query this service or DNS, to resolve the address to your application.
There's a similar question ( Can I temporarily override DNS resolution within a .NET application? ) but I just can't figure it out with the meager response there.
Background info
I have a server set up in my home network, an old computer. Our router has the right ports forwarded, the server runs server software for things like http, svn, games, etc. I've got a domain name registered that always points to our external IP address. For all intents and purposes, I've got a typical webserver set up. My friends can game on my server by connecting via the domain name, I can push and pull svn projects, etc.
The only problem is that I also need to use my server when I'm connected to my home network (the same network as the server). Using the domain name results in Windows resolving it to our own IP address, and my router is too retarded to realize it just needs to forward it back into our network to the server as per the usual. I've done some looking around, configuring, telnetting and DNS overriding, but I have it on good authority that our ISP apparently crippled the DNS override feature of their routers to prevent this exact scenario. Apparently they don't like internal loopbacks.
I now basically have to keep 2 configs for each of my server's services: one config that specifies the domain name for when I'm abroad, and a second that specifies the server's internal IP for when I'm at home. It's frustrating because it just isn't always possible.
I want to instantiate a global DNS resolution request/response listener that will do the following: if the requested domain name matches a given string, override the IP in the response with one of my choice.
I've looked things up like easyhook, dllimport, msdn pages, etc, but I still can't figure out where to actually start, which classes I need to get access to, and so on. I basically have no pre-existing code for this particular problem.
I have Visual Studio, years of relatively simple programming experience and a good understanding of unfamiliar code and everything else, just no idea how to start or what to look for.
Many thanks for anything that can get me going.
Couple of pointers, DNS is as you mentioned some server somewhere that knows how to resolve a Domain name to an IP ADDRESS. There are two types of responses 1) Definitive for the domain and 2) Not Definitive for the Domain. Obviously any Definitive response will win.
DNS does not run at TCP/IP layer it runs one layer below using UDP (port 53). As a result DNS is tied into the TCP/IP stack whereby the stack first looks locally to a local host table and sees is the name is there, if it cannot find it the stack will send out the DNS request prior to the session start or SYN packet flying. In order for this to happen, the DNS servers must resolve the address.
I do not fully understand your issue because most Windows servers only have 1 IP Address and one associated Domain name. Unless of course they are using DHCP which just means the server uses multiple address on boot up and DNS server receive updates to what those new address are.
Public vs. Private IP addresses are the responsibility of a router. The router is configured to do NAT (Network Address Translation). This allows a private server to have unroutable addresses like 10.10.1.100 etc. But the router will answer ARPs for the public address making the public network think the router is the public address. So one of your solutions could be to convert your server to a private address and use a "real" router that can perform NAT. Port forwarding is not really routing rather it's a way to "trick" packets destined for one port number to be forwarded to another port dedicated for that application.
My suggestion is to either follow the suggestions above or add the Domain names you want to the local Host table on the server. This will get you what you want. A better solution is to configure your own server to be a DNS server definitive for your domain, that way you get to control everything.
I ended up solving this with (as a few have suggested) the hosts file after all.
I first used ManagedWifi to set a network connection monitor. It detects changes to my connection status and reports the network name.
Then I wrote a console app that stays open (using Hidden Start allows me to hide the window) and safely modifies the hosts file, then flushes the DNS cache. This seems to work in pretty much realtime. :)
How to build Opera unite like functionality using .NET?
When we run opera browser and enable the opera unite then it shares our desktop on web and we can access it over internet without having a static IP, how does this works?
You need to map your dynamic IP to some static DNS name. One easy to use solution would be a DynDNS service. For these you get a small client program (or good routers already have a dyn dns client already implemented), that simply maps your current ip address to a specfic dns name.
After getting this done it depends on how variable you like it:
- Do you have one master that should be able to look on various client PCs for help?
- Do you like to connect two clients which are both have dynamic ips?
In the first case your master is the one how always ensure to map his current ip address to the dns name. On the router maybe some port forwarding is needed and your clients get a vnc client with reverse mode enabled. This allows everyone to built up a connection to your master and sharing the desktop without any changes on the client site. Only on the master site has something to be done (dynDns and port forwarding).
In the second case it is a little bit more complicated. Now you got two dynamic IPs that like to connect to each other. This is normally be done through some kind of mediator. Means both machine connect to some master (reachable through some DNS name). Now both machines have a bi-directional connection to the master and the master will simply take the data from the first client and forwards it to the second and vice versa. To take all the burden from the master it would be possible that the master in a first step sends the ip address of client A to B and vice versa. Then in a first step both trying to connect to each other directly. This method is known as UDP hole punching and does not always work, which then leads to a fallback to use the master instead.
Two examples that are using the second approach are Skype and join.me.
All these techniques don't have to do anything with .Net. It is pure knowledge about ethernet, TCP/IP, internet, etc. And due to the fact that you have to do a lot of work in this low-level area i would think that C# is not the ideal framework to accomplish this task. Maybe to put the GUI as last step over it all, but for the real work behind the scenes you need some decent network know-how which is mostly independent from the programming language you are using.
You should run your own DNS server. And whenever an user opens the browser and logs in, you should send the current IP address of the user to your server and update in your local DNS. Since you will have only a subdomain (desktop.operaunitecom), whenever someone hit your url it first goes to operaunite DNS server from where it will fetch your IP address. When the user's session closes you should remove the DNS entry. This could be a possible solution.
Is it possible to write C# code as below and send email using mnetwork in different country?
MSExchangeWebServiceURL = mail.something.com/ews/exchange.asmx
It's a web service URL. This works great when I run the same code from home network, my friends home network anywhere around, but when I run it from my client's location in Columbia it fails.
I have a valid user name and password on that Exchange Server. Is there any configuration that I can set to achieve this?
BTW this code below works when I run it within office network and any network within any home network. I have tried it at least with five friends network in Plano, Texas. I want this code to work running from any network in another country.
My client in Columbia can connect to the web service using a browser using the same user name and password, but when I run the code above it is not able to connect to our web service.
EDIT: Based on the comments and updated post, I would wager that the client location has a proxy server or firewall that is blocking the traffic. The client probably needs to add the relevant domain to whatever "whitelist" they have.
If it works from an internal network, then the problem is most likely not the code. You need to debug it and see what error turns up when running it outside of the network. Then check the logs on the firewall and the target exchange server to see what is happening.
One possible culprit is that the DNS name is not setup outside the office network, or that the office firewall is not setup to pass traffic (or only to pass SMTP traffic) from the internet to the server in question. Another is that Exchange Web Services is not setup properly to accept requests from the outside world. That can be tested from http://www.testexchangeconnectivity.com/.
If this isn't enough for you to get there, post more info about what errors you are seeing. "It isn't working, I want it to work" kind of reminds me of the Star Trek TNG episode about the species who kept telling Geordi to "make it go".
If you are asking if the code works (which it doesn't look like you are but it's in your post) you should ask on stackoverflow. If you are wondering why it won't work from home Its likely because the edge server is not set up to relay, and if you are at home and not vpn'd into the network that's all you have access to.
You need to break this down a bit:
What's the MSExchangeWebServiceURL? I don't need to know your real URL, but is this resolvable from your home network? i.e. is it an internal DNS host (server.mycompany.local) or is it an externally-resolvable DNS host (mail.yourcompany.com)?
If it's internal, like another poster said, you'll at least need to VPN in (or replace that with the external URL).
I'm not a big C# guy, but I'm guessing it's looking for your Exchange Server hostname or FQDN, and since the type is "SMTP" it wants to establish a TCP session with your mail server. You can likely test this out by opening up your command prompt and trying to telnet <MSExchangeWebServiceURL> 25. When that works, my guess is your code will work too.
I have web service on server! This service is calling from the clients applications!
Now how i can get user name and computer name of clients that using this service, for example if application from Clint1 calling this service i want to get computer name and user name of Clint1?
Many thanks!
You can't reliably, really.
The server variable REMOTE_HOST may provide you with it, but in most cases it will be an IP address and it could well be a proxy's IP address. Also - it is something that can be easily spoofed.
Same goes for username (REMOTE_USER), unless you use some WS-Security mechanism to authenticate the user calling your webservice.
The client will have to be passing this information to the service.
As Wim said, you can't get this information reliably. For a guaranteed Windows network you can retrieve the current authenticated user (to the machine) using the server variable:
System.Web.HttpContext.Current.Request.ServerVariables("LOGON_USER")
The REMOTE_HOST variable is supposed to return the machine name, but in most cases (as he said) it will only be an IP address.
Even on a LAN, this is not an advisable security practice. This information can still be spoofed locally providing internal users the capability to masquerade as other users. If it's simply being used for identification (rather than authentication or authorization) it would probably be "good enough". If you maintained a small datatable (or the networking team) that identified each pc to its expected IP address, this information would achieve what you want.