I know already about the web-sockets, and they are great, the problem with them is that they have to keep the connection open in order to be able to communicate.
I have a small system where from time to time the server has to update the status and notify the clients about that, and keeping the connection open from every client is not so optimal. At same time is very important that the update on the client side to be made just in time.
So my question is, if the server has a unique address does the client have a public temporary address where the server can send request? So when the client will connect to the server it will provide it's unique address and the server will cache it, and when there will be an update the server will send the request to that address?
I understand that there many problems as the address will constantly change, but this is already other question.
If client does not have a dedicated IP-address then it is not available from WAN unless it has an open connection with any node in it.
When client from local network sends request to a server it's (client's) router remembers client's local IP-address and port and translates it using NAT protocol to one of router's free ports and then sends data further with router's own 'IP-address of the sender' in IP protocol header and 'Sender's port' in TCP header. When router get's server's response it uses NAT table from it's memory to translate addresses back and deliver data to the client. Addresses are normally kept in NAT table while connection between server and client is open. So if there are no opened connections between server and local network client then server will not be able to connect with client because server does not know how to reach it.
You say you have a small system. Why then do you think that you will not have enough free ports at your server to work with websockets? If you just want to get updates from the server (not to both send and get data through a persistently opened connection) you'll probably find long polling or SSE more suitable. It is definitely easier to implement than websockets.
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So I am trying to create a p2p file sharing application in Golang. I am running a globally accessible server for the purpose of sharing IP addresses of 2 clients. When both the clients have each other's IP addresses, they can use hole punching to share the files.
But I am facing some problems in the hole punching part. When I send a request to server, the server is going to store the address of the client and it will later relay this address to other client. Problem is that the address being stored on the server is different than the address that is being is used for Hole punching. Suppose that address being stored on server is NATrouterIP1:PORT-A for first client and NATrouterIP2:PORT-B for the second. But when I am using the first client to send a message to second client, it shows that the message was sent from NATRouterIP1:PORT-C. PORT-A generally stays around 65000. But this PORT-C is 1024. For my application to work these ports should be same. Can someone explain what the issue is?
Github: https://github.com/killtheverse/go-send
my question is simple
When you send data through TCP/IP protocol with EX:firefox you can receive reply on some random port that the browser listen on, while when i try to use a port for another task like CS Gaming or anything else it don't work unless i use kind of VPN ?
PS: there r no firewall blocking connection and port forwarding from my router didn't work as well.
Browsers are client apps that make outbound connections to web servers. When connecting to a server through a router’s NAT, the NAT takes note of the source and destination IP/port pairs so messages sent back from the server on the same connection are automatically routed to the correct client IP/port.
Browsers also support the websocket protocol. This feature makes it seem like the browser is listening on a specific port. However, in reality, it is initiated on a new connection to the server, a connection which remains open all throughout the websocket communication.
What matters is which peer is behind the NAT — the server or the client. For an outbound connection from a client, it can usually use any random port that is available at the time. For an inbound connection to a server, the server's IP/port must be known ahead of time and be routable. If the server is behind a NAT, the router(s) must be configured to make the server reachable from the other side of the NAT.
The server software can make a UPnP request to ask a router to forward inbound packets to the correct IP/Port. The router, depending on its configuration, may or may not honor such a request. If not, the router has to be configured manually by a network administrator.
I am trying to develop a lan chat application. As I looked for the topic, I found that whatsapp, viber etc. use a server which controls all the traffic. The server tells the status of devices and manage all traffic etc. So, what am I trying to know is :
How the server gets the info of devices like, IP address, MAC address etc?
How the data is transferred from one client to server and then server to another client?
Which language should I use server side?
As shown in image, I want to connect two devices, A and B and interchange data between them.
Actually, I'm not sure data always through the server. From what I know, the client logs in at the server the first time it connects only. If client A wants to send a message to client B, it retrieves the IP corresponding to username_B from the server, then exchange of data is done directly between client.
What you should do is to develop a protocol to login at the server and register the client IP, and to retrieve an IP from a username.
For the routers between server and clients, I think it is out the server scope, you just need for NAT.
If I am not wrong, to have a push technology the client ( say browser ) also needs to run a small web server which is listening on some port ( say ijetty runs on 8080 ). Now when the actual server comes to know about any event, it sends the event to client. This way there is no PULL mechanism involved at all. Is this right ? OR there is a persistent connection involved and server sends the data on that connection whenever the event happens. My question is : in the former case ( if it is true ), how does server know about client's IP ?
WebSockets working with socket based on TCP connection, basically the client make a request for connection to the server with a challenge, websocket version, ip and more data, then the server decrypts the challenge and return his result back to the client, this process called Handshake.
If the handshake is approved, the connection is made, the socket connection remains open between the client and the server, heartbeats will be sent from the server to the client like a ping to check if the connection is still open.
read this wiki to find out more:
http://en.wikipedia.org/wiki/WebSocket
i was reading this topic
http://ftp.icm.edu.pl/packages/socks/socks4/SOCKS4.protocol
and what im trying to do is:
i have a client/server application, what im trying to do is to use socks 4 BIND request to bind my server to a remote socks server, and make the clients connect to that socks server and the socks server will make them connect to my server (at least thats how i understand socks BIND request)
but i don't fully understand it (my English is kinda bad), what im asking is, is it possible to do so when i dunno any of the remote IPs of the clients? since the server's BIND request package must contain the address of the remote client and i dont really have than since the clients are from unknown users retrieving status info from my server (or can i use 0 for INANY_ADDR) ?
What you are asking for is not possible with SOCKS, nor is it meant for that purpose. Read the spec again more carefully. The BIND command is meant for use with multi-connection protocols (like FTP), where a primary connection is used to communicate between a client and a server, and BIND facilitates situations where the server needs to connect a secondary connection to the client after the client tells the server where to connect. In that situation, the client would issue a BIND command to SOCKS telling it the server's IP/Port so it only accepts that connection, then send the resulting SOCKS listening IP/Port to the server to connect to.
What you are asking for is better served by using a router with Port Forwarding rules defined. Then you can open a listening port on the router that accepts any inbound connection and forwards it to your app's listening IP/Port. Most modern routers support uPNP (Universal Plug-N-Play) so you can configure the forwarding rules programmably instead of requiring admin access to the router's configuration software.