I have written a client/server code.
The server program executes on a terminal which plainly receives text data from the client and the client is a GUI where in you could specify the IP address of the machine where the server would be running.
However this works only in a closed Network(LAN).
I have just learnt TCP IP and have written a few codes that run on a LAN.
I wanted to make this program work across the network(over the internet).
But I have some basic doubts like,does one need the permission of the local ISP for such programs to execute across the internet.Does it involve buying a domain or some kind of permissions?
Can some one please help me on,what should I be doing,or where should I start from?
Listener have to have IP port opened in some way. If you are behind router, you should set proper port forwarding on router and if ISP provides its own subnet, you should know how to setup such link. (i do not know what kind of tehnology ISP might use for this).
For beginning you do not need you own domain name but you should be able to address by ip. If you need domain, register own domain name or create subdomain for free (i was using http://freedns.afraid.org/ )
If your server is behind a router which creates a LAN, you have to configure the router that it will forward the packages from your client to the server.
You have to forward all the incoming packages at the specific port to the local ip of the server.
Related
Currently in my chat p2p app, I need to open the port for other computers can connect to, but static ip is not allowed by the admin to open the port. Then I found a network programming exercise that seemed like a solution to this problem. The requirements are as follows:
"Write a program to test the UPnP protocol to
ADSL modem controller opens NAT gateway automatically.
In case you can not control the modem, find out and install a NAT Traversal technique to connect two clients in two NAT networks.
internet (use an intermediary server for primers
connect)."
Can anyone tell me what is an intermediate server for connection primitives?
Check https://www.noip.com/ :P. Maybe this can solve some of your problems ^^
You can simple setup DynDNS services. You will have one external domain name with any ip address.
But best way to setup SoftEther VPN solution. That can pass thought any NAT. You can keep your application server at the NAT subnetwork too. And that server will registered on common EtherVPN registry that allow connects from anywhere.
If you want smart solution embedded in your application. Please check similar solutions for VoIP communications. Like ICE, STUN, TURN. But that will not simple to implement.
Now that apple has changed their review environment to an IPv6 only network ive been running into troubles with my application while testing.
The application requires the user to input their server/systems IP address, port (4401) and credentials to gain access to the application. Following the guidelines provided by apple i set up a NAT64 environment to test my application's compatibility. Running iOS 9.3.2 on an iphone 5s.
My work environment has several internal networks. I connected my iMac to the internal server (10.10.50.XX) via Ethernet which also has an external IP which is what i provide to apple. The 50 network does not run behind a proxy, but there are some sites which get filtered, but can access by confirming. I then shared my Ethernet connection through WiFI.
I connected the device and had internet access with the same pages being filtered. The device gets assigned a local-link address of 169.254.XX.XX. From what ive read my device is connecting to the ipv6 only network correctly, as the iphone does not show the ipv6 address only local link.
If I am correctly connected to the shared IPv6 network, the problem I am having is connecting to my server on the 50 network from my application. The application fails when ever i try to connected to the 10.10.50.XX network or the external(understandable because my imac is on the 50 internal network) .
Testing the application using IPv4 with a wireless router that is connected to the 50 network runs perfectly.I think it is an issue with the local link address not being able to see the 50 network or something.
Heres some brief background info on how i connect to the server. The user inputs all the credentials and the IP address and port of the server they want to connect to. The application saves this as a text (utf-8) and uses boost shared_ptr to send it to the cpp connection class which validates the credentials and provides access to the user. This cpp connection class handles the connection, synchronization, logging, requests and response from the server.
Is it possible to somehow get access to the 50 network, using the NAT64 internet sharing option?
If you're passing an IP address straight down to your network lib, then no. When your device is on the IPv6-only side of the NAT64, the server's IPv4 address is useless.
You almost certainly need a DNS name for the server you're trying to reach. The NAT64 relies first on DNS64 to create IPv6 addresses for your application when the server is IPv4-only. These synthesised addresses contain the IPv4 address(es) for the server, giving the NAT64 the information it needs to translate from IPv6 to IPv4.
Updating this to add: as suggested by user102008 in the comment thread attached to this answer, you may also be able to pass the IPv4 string literal though getaddrinfo() (see code listing 10-1 on this page). When you're behind a NAT64, a synthesised IPv6 address should be among the results returned by that call. The NAT64 will translate from this address back to IPv4 to reach the host you specified. In this case, if the system knows the correct prefix to use for the NAT64, a hostname is not necessary.
I'm writing a program on Windows using winsocks that can send messages to another computer. The client connects with the server in the other computer and begin exchanging data.
It works fine on my local network using local addresses(192.168.1.*), but I can't communicate with public addresses (216.185.45.129); not even my own. I can successfully connect to a website on port 80, but not to my laptop at home using its public IP address, regardless of what ports I use (unreserved ports).
So I did research online and the only solution that seems to work is port forwarding.
-But is there absolutely no other way to achieve this?
-How do other programs like Teamviewer connect to other computers on the network then?
-Is there an already open but typically unused port that I can use?
-At the very least, can I forward the ports on my router but not have the client do anything? Or maybe have my program forward the ports automatically.
The main problem is, that every router is using NAT to distinguish different computer in your lokal network against the WAN. He need to do this, because you got only one IP in the internet, but several devices in your home. To archive this, he uses groups of ports. That means, if you use to send maybe from port 2048 to a webserver in internet with two devices, the router gives one device another port (like 2049). The response has the Port of the requester, so the router can map it back. Unfortunately most router always map ports so you never now which port you have from the internet side.
There are two common ways to work around and archive your goal.
Port Fowarding
You can force most router not to map special ports but bind them to unique MAC addresses. You can use UPNP to config most router to do that, but I do not recommend that for security reasons and also it does not work in many enviroments where Router do not allow UPNP manipulation.
Most router have port forwarding abilities for gaming reasons (mostly it is used in P2P networks)
It works with TCP and UDP.
NAT Traversal
The common way is NAT traversal, also known as NAT hole punching. I will describe it in short for UDP. You can find a wiki explanation here for TCP and for UDP here. Unfortunately you need a server in the internet both clients can reach. Here the steps:
Both clients contact the server. The server now know IP and PORT of both clients.
Server send back the information to the clients.
Both(!) clients send now packages to each other on the known address.
It is necessary that both client send a UDP package and have to accept that the first package get lost. The reason is the router. Most router only accept packages from a source on a mapped PORT if a client has send a package to that source before.
UPDATE
Regarding to a comment of Remy Lebau I changed the Firewall piercing part to NAT Traversal as it was partly wrong.
I'm writing a very simple server-client application in C++, using WinSocks.
When I set client's parameters as: resolveHost ("google.pl") for server's IP and 80 for port, I receive a html (with GET header).
When I run the server first (with port 10000) and then client (port 10000 IP inet_addr("127.0.0.1") it seems to works (I receive something).
But when I change the server's IP in client to inet_addr("188.246.158.171") (my IP for now, I don't have static IP, I've checked my actual IP with some website), it for sure DOES NOT works.
My computer is behind the router - can it be the problem?
If so, can I solve it in the way that don't requite any configuration to router (port forwarding etc.). Also, I don't want to make anything router's model-specific, so I intentionally haven't posted the model of my router ;)
Why I don't want to change configuration?
Because my application will be for "simple people". And simple people won't try to make configuration, and I won't require them to do so.
Also, many applications (on-line games for example) works fine with my router without any configuration - my application cannot be exception (by the example of other applications on my computer, I know it's possible and common to achieve it).
I use Visual Studio 2012, works on Windows 7 x64.
If you run a listening server behind a router, you must configure port forwarding rules on the router if you want outside clients to reach the server through the router. You cannot avoid that. However, if the router supports uPnP (Universal Plug and Play), your server code can configure port forwarding rules programmably, such as with Microsoft's IUPnPNAT interface. Otherwise, you have to use the router's own configuration software (usually an HTTP interface running on the router itself).
You also have to configure ports/permissions on a local firewall, if installed. Some firewalls have APIs for that, such as Microsoft's Firewall.
Online games and other peer-to-peer apps employ several NAT Traversal techniques to get around NATs, firewalls, etc. Hole Punching, Role Reversal, etc. Do some searches, information is readily available.
I'm currently writing a peer-to-peer chat application to chat around the world, but my problem is that I can't connect() to another computer outside my LAN because although I have the public IP address of my friends and if necessary I could get their private IP address, how can I connect to their PC since the public IP address is the router's address, not the computer's one and I can only specify one address (either the public or the private). So how can I send the message to the computer in specific and not to the router without having to setup it?. I know it's possible because otherwise if you requested a web page all the computers in your lan can get your private information (in a wired scheme, since in wi-fi it's clearly possible).
Any help would be appreciated, sorry for my poor English :D.
There are two possibilities:
1 Read around here: http://en.wikipedia.org/wiki/STUN
2 Go for IPv6! ;-)
Actually the private IP address of computers on the other side of the router will not help you. In these situations, if they initiate the connection to you, then you are fine as you can respond on that connection.
If you want to initiate the connection to them, you must to it to their public IP address and they must have their router configured to map the inbound request (on whatever port) to the correct IP address in their network.
First, you need to be sure that the computer you are trying to connect is listening to a specific port (the same one that you are trying to connect to).
You will also need to configure your friends routers so that they forward all the request on that port to your friends' computers. If you don't have access to the routers, it is probably best to use a computer that is not behind any router as the chat server.
The ideal solution is to use uPNP. This allows your application to talk to the router(s) on the current network and ask them to forward the appropriate messages to you. This then makes a hole in the firewall which allows your app (on another PC) to connect.
Assuming both apps do this, either end can initiate the connection. If only one end has the app, then the OTHER end must initiate connection.
Imagine what would happen if everyone on the internet could just send messages to anyone - with no software pre-installed...