Yes, you can use the same port number for both TCP and UDP.  Many protocols already do this, for example DNS works on udp/53 _and_ tcp/53.

Technically the port pools for each protocol are completely independent, but for higher level protocols that can use either TCP or UDP it&#39;s convention that they default to the same port _number_.

When writing your server, bear in mind that the sequence of events for a TCP socket is much harder than for a UDP socket, since as well as the normal `socket` and `bind` calls you also have to `listen` and `accept`.

Furthermore that `accept` call will return a new socket and it&#39;s _that_ socket that you&#39;ll then have to also poll for receive events.  Your server should be prepared to continue `accept`ing connections on the original socket whilst simultaneously servicing multiple clients each of which will be triggering receive events on their own sockets.


Firstly,there is no problem using both tcp and udp on the server.

Secondly,we can have both UDP and TCP requests on same port ,because each request is identified by a quintuple contained by source IP ,Destination IP, Source Port, Destination Port, PROTOCOL(as protocol can be TCP or UDP).

currently I have the following:

	$.ajax({
		type: &#39;POST&#39;,
		url: this.action,
		data: $(this).serialize(),
	});

This works fine, however I would like to add a value to data, so I tried

	$.ajax({
		type: &#39;POST&#39;,
		url: this.action,
		data: $(this).serialize() + &#39;&amp;=NonFormValue&#39; + NonFormValue,
	});

But that didn&#39;t post correctly. Any ideas on how you can add an item to the serialize string? This is a global page variable that isn&#39;t form specific.

$(this).serialize() -- How to add a value?

How can I select a particular range of rows in a `DataGridView` programmatically at runtime?

Selecting a row in DataGridView programmatically

First of all, is there any problem with using both UDP and TCP on the same server?

Secondly, can I use the same port number?

Can TCP and UDP sockets use the same port?

<p>First of all, is there any problem with using both UDP and TCP on the same server?</p>
<p>Secondly, can I use the same port number?</p>


Is there a c# client that follows the socket.io protocol? I have a socket.io server that is communicating with a socket.io javascript client via a website, but i also need to connect a c# piece to it that can send and receive messages. Is there a clean way to do this currently or will I have to write my own client.

Communicating with a socket.io server via c#

Is the new C++11 going to contain any socket library? So that one could do something `std::socket`-ish?

Seeing as how `std::thread` will be added, it feels as if sockets should be added as well. C-style sockets are a pain... They feel extremely counter-intuitive.

Anyways: Will there be C++ sockets in C++11 (googled it but couldn&#39;t find an answer)? If not, are their any plans on adding this? Why (/ why not)?

Will (and should) there be sockets in C++11?

What is the difference between AF_INET and PF_INET in socket programming?

I&#39;m confused between using AF_INET and PF_INET in `socket()` and `bind()`.

Also, how to give ip-address in `sin_addr` field?

What is the difference between AF_INET and PF_INET in socket programming?

What is a good way to communicate between two separate Python runtimes? Thing&#39;s I&#39;ve tried:

- reading/writing on named pipes e.g. [`os.mkfifo`](https://docs.python.org/3/library/os.html#os.mkfifo) (feels hacky)
- [`dbus`](https://wiki.python.org/moin/DbusExamples) services (worked on desktop, but too heavyweight for headless)
- sockets (seems too low-level; surely there&#39;s a higher level module to use?)

My basic requirement is to be able to run `python listen.py` like a daemon, able to receive messages from `python client.py`. The client should just send a message to the existing process and terminate, with return code `0` for success and nonzero for failure (i.e. a two-way communication will be required.)

Interprocess communication in Python

From test, I concluded that in following three cases the `socket.recv(recv_size)` will return.

1. After the connection was closed. For example, the client side
   called socket.close() or any socket error occurred, it would return
   empty string.

2. Some data come, the size of data is more than `recv_size`.
3. Some data come, the size of data is less than `recv_size` and no more data come after a short time (I found 0.1s would work).

More details about #3:

    #server.py
    
    while True:
        data = sock.recv(10)
        print data, &#39;EOF&#39;

    #client1.py

    sock.sendall(&quot;12345&quot;)
    sock.sendall(&quot;a&quot; * 50)

    #client2.py

    sock.sendall(&quot;12345&quot;)
    time.sleep(0.1)
    sock.sendall(&quot;a&quot; * 50)

When I run `client1.py`, the `server.py` echos:

    12345aaaaa EOF
    aaaaaaaaaa EOF
    aaaaaaaaaa EOF
    aaaaaaaaaa EOF
    aaaaaaaaaa EOF
    aaaaa EOF

When I run `client2.py`, the `server.py` echos:

    12345 EOF
    aaaaaaaaaa EOF
    aaaaaaaaaa EOF
    aaaaaaaaaa EOF
    aaaaaaaaaa EOF
    aaaaaaaaaa EOF


Are my conclusions correct? Where can I see the official description about #3?

When does socket.recv(recv_size) return?

In the internet there are several places that show you how to get an IP address. And a lot of them look like this example:

    String strHostName = string.Empty;
    // Getting Ip address of local machine...
    // First get the host name of local machine.
    strHostName = Dns.GetHostName();
    Console.WriteLine(&quot;Local Machine&#39;s Host Name: &quot; + strHostName);
    // Then using host name, get the IP address list..
    IPHostEntry ipEntry = Dns.GetHostEntry(strHostName);
    IPAddress[] addr = ipEntry.AddressList;

    for (int i = 0; i &lt; addr.Length; i++)
    {
        Console.WriteLine(&quot;IP Address {0}: {1} &quot;, i, addr[i].ToString());
    }
    Console.ReadLine();

With this example I get several IP addresses, but I&#39;m only interested in getting the one that the router assigns to the computer running the program: the IP that I would give to someone if he wishes to access a shared folder in my computer for instance.

If I am not connected to a network and I am connected to the internet directly via a modem with no router then I would like to get an error. How can I see if my computer is connected to a network with C# and if it is then to get the LAN IP address. 



Get local IP address

I&#39;m trying to implement a TCP connection, everything works fine from the server&#39;s side but when I run the client program (from client computer) I get the following error:
   

    java.net.ConnectException: Connection refused
        	at java.net.PlainSocketImpl.socketConnect(Native Method)
        	at java.net.PlainSocketImpl.doConnect(PlainSocketImpl.java:351)
        	at java.net.PlainSocketImpl.connectToAddress(PlainSocketImpl.java:213)
        	at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:200)
        	at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:432)
        	at java.net.Socket.connect(Socket.java:529)
        	at java.net.Socket.connect(Socket.java:478)
        	at java.net.Socket.&lt;init&gt;(Socket.java:375)
        	at java.net.Socket.&lt;init&gt;(Socket.java:189)
        	at TCPClient.main(TCPClient.java:13)

I tried changing the socket number in case it was in use but to no avail, does anyone know what is causing this error &amp; how to fix it.

The Server Code:

    //TCPServer.java
 
    import java.io.*;
    import java.net.*;
    
    class TCPServer {
    	public static void main(String argv[]) throws Exception {
    		String fromclient;
    		String toclient;
    
    		ServerSocket Server = new ServerSocket(5000);
    
    		System.out.println(&quot;TCPServer Waiting for client on port 5000&quot;);
    
    		while (true) {
    			Socket connected = Server.accept();
    			System.out.println(&quot; THE CLIENT&quot; + &quot; &quot; + connected.getInetAddress()
    					+ &quot;:&quot; + connected.getPort() + &quot; IS CONNECTED &quot;);
    
    			BufferedReader inFromUser = new BufferedReader(
    					new InputStreamReader(System.in));
    
    			BufferedReader inFromClient = new BufferedReader(
    					new InputStreamReader(connected.getInputStream()));
    
    			PrintWriter outToClient = new PrintWriter(
    					connected.getOutputStream(), true);
    
    			while (true) {
    
    				System.out.println(&quot;SEND(Type Q or q to Quit):&quot;);
    				toclient = inFromUser.readLine();
    
    				if (toclient.equals(&quot;q&quot;) || toclient.equals(&quot;Q&quot;)) {
    					outToClient.println(toclient);
    					connected.close();
    					break;
    				} else {
    					outToClient.println(toclient);
    				}
    
    				fromclient = inFromClient.readLine();
    
    				if (fromclient.equals(&quot;q&quot;) || fromclient.equals(&quot;Q&quot;)) {
    					connected.close();
    					break;
    				} else {
    					System.out.println(&quot;RECIEVED:&quot; + fromclient);
    				}
    
    			}
    
    		}
    	}
    }
    
The Client Code:

    //TCPClient.java
    
    import java.io.*;
    import java.net.*;
    
    class TCPClient {
    	public static void main(String argv[]) throws Exception {
    		String FromServer;
    		String ToServer;
    
    		Socket clientSocket = new Socket(&quot;localhost&quot;, 5000);
    
    		BufferedReader inFromUser = new BufferedReader(new InputStreamReader(
    				System.in));
    
    		PrintWriter outToServer = new PrintWriter(
    				clientSocket.getOutputStream(), true);
    
    		BufferedReader inFromServer = new BufferedReader(new InputStreamReader(
    				clientSocket.getInputStream()));
    
    		while (true) {
    
    			FromServer = inFromServer.readLine();
    
    			if (FromServer.equals(&quot;q&quot;) || FromServer.equals(&quot;Q&quot;)) {
    				clientSocket.close();
    				break;
    			} else {
    				System.out.println(&quot;RECIEVED:&quot; + FromServer);
    				System.out.println(&quot;SEND(Type Q or q to Quit):&quot;);
    
    				ToServer = inFromUser.readLine();
    
    				if (ToServer.equals(&quot;Q&quot;) || ToServer.equals(&quot;q&quot;)) {
    					outToServer.println(ToServer);
    					clientSocket.close();
    					break;
    				} else {
    					outToServer.println(ToServer);
    				}
    			}
    		}
    	}
    }

java.net.ConnectException: Connection refused

I&#39;ve successfully installed MongoDB on Windows (on a local machine) as a service, but now I want to move MongoDb to a separate server. So I extracted the tarball to a virtual server on network (running linux).

When I connected to the server (&quot;testmongoserver&quot;) using PuTTY from my local machine, I started the mongod server and it told me that it was listening to the default 28017 port. The mongo console is also working and allowed me to create a new database (testdb) and add users to it.

However, I could not access the server from remote. When I type `testmongoserver:28017` it doesn&#39;t open the HTTP console as `localhost:28017` on my local machine does. I also can&#39;t connect using official drivers and providing a connectionstring.

What are the neccesarry steps to install MongoDB on Linux, so that I could access it from a remote machine with a connectionstring and use its HTTP console via `testmongoserver:28017`

Thanks!

Getting MongoDB on Linux to listen to remote connections

I have a file that I would like to copy from a shared folder which is in a shared folder on a different system, but on the same network. How can I access the folder/file? The usual open() method does not seem to work?

Using Python, how can I access a shared folder on windows network?

Endianness from what I understand, is when the bytes that compose a multibyte word differ in their order, at least in the most typical case.  So that an 16-bit integer may be stored as either `0xHHLL` or `0xLLHH`.  

Assuming I don&#39;t have that wrong, what I would like to know is when does Endianness become a major factor when sending information between two computers where the Endian may or may not be different.

 * If I transmit a short integer of 1, in the form of a char array and with no correction, is it received and interpretted as 256?

 * If I decompose and recompose the short integer using the following code, will endianness no longer be a factor?


        // Sender:
        for(n=0, n &lt; sizeof(uint16)*8; ++n) {
            stl_bitset[n] = (value &gt;&gt; n) &amp; 1;
        };

        // Receiver:
        for(n=0, n &lt; sizeof(uint16)*8; ++n) {
            value |= uint16(stl_bitset[n] &amp; 1) &lt;&lt; n;
        };
 *  Is there a standard way of compensating for endianness?

Thanks in advance!

When does Endianness become a factor?

How can I write a website using *HTML5*, *CSS* and *JavaScript* on client side that will allow **direct tcp/ip connection between the client browsers once the page is loaded**.

I need to do this to to reduce latency since the site will require that the input from one of the users to be transmitted to the other user as soon as possible so sending data from client A to Server and then to client B is not a good option.

I read previous posts on this subject but there were no working solution/examples available that I could find. From what i read the direct connection between clients can be made using plugins like Silverlight, Java or Flash.

Is there any solution that would not require plugins? I would like to use only JavaScript.

How can I make a browser to browser (peer to peer) connection?

I&#39;m having a problem with a library that I am using. It might be the library or it might be me using it wrong!

Basically, when I do this (Timeout in milliseconds)

    _ignitedHttp.setConnectionTimeout(1);  // v short
    _ignitedHttp.setSocketTimeout(60000);  // 60 seconds

No timeout exception is generated and it works ok, however, when I do the following,

    _ignitedHttp.setConnectionTimeout(60000);  // 60 seconds
    _ignitedHttp.setSocketTimeout(1);          // v short

I get a Socket Exception.

So, my question is why can I not simulate a Connection Exception? Am I misunderstanding the difference between a socket and a connection time-out? The library is [here][1] (not officially released yet).


  [1]: https://github.com/kaeppler/ignition-support/tree/master/src

ConnectionTimeout versus SocketTimeout

What exactly is a TCP connection?
I understand there isn&#39;t a physical connection from the client to server. Is this connection just the client&#39;s socket being linked with the new socket created by the server after the three-way-handshake? 
Thereafter once the &quot;connection&quot; is set up, the sockets on either ends of the connection then know where to send their packets.

How does this differ from the way UDP functions other than the initial handshake with TCP?
Is it that each server socket only has one client that sends packets to that particular socket?

What are some possible advantages of having a dedicated connection between hosts? My understanding of TCP and UDP is still very basic, so broad generalizations should suffice.

TCP vs UDP - What is a TCP connection?

How to write a echo server bash script using tools like nc, echo, xargs, etc capable of simultaneously processing requests from multiple clients each with durable connection?

The best that I&#39;ve came up so far is

    nc -l -p 2000 -c &#39;xargs -n1 echo&#39;

but it only allows a single connection.

How to make an Echo server with Bash?

Sorry about the length, it&#39;s kinda necessary.

**Introduction**


I&#39;m developing a remote desktop software (just for fun) in C# 4.0 for Windows Vista/7. I&#39;ve gotten through basic obstacles: I have a robust UDP messaging system, relatively clean program design, I&#39;ve got a mirror driver (the free DFMirage mirror driver from DemoForge) up and running, and I&#39;ve implemented NAT traversal for all NAT types except Symmetric NATs (present in corporate firewall situations).

Regarding screen transfer/sharing, thanks to the mirror driver, I&#39;m automatically notified of changed screen regions and I can simply marshal the mirror driver&#39;s ever-changing screen bitmap to my own bitmap. Then I compress the screen region as a PNG and send it off from the server to my client. Things are looking pretty good, but it&#39;s not fast enough. It&#39;s just as slow as VNC (btw, I don&#39;t use the VNC protocol, just a custom amateur protocol).

From the slowest remote desktop software to the fastest, the list usually begins at all VNC-like implementations, then climbs up to Microsoft Windows Remote Desktop...and then...TeamViewer. Not quite sure about CrossLoop, LogMeIn - I haven&#39;t used them, but TeamViewer is *insanely* fast. It&#39;s quite literally live. I ran a `tree` command on Command Prompt and it updated with 20 ms delay. I can browse the web just a few milliseconds slower than on my laptop. Scrolling code vertically in Visual Studio has 50 ms lag time. Think about how robust TeamViewer&#39;s screen-transfer solution must be to accomplish all this.

VNCs use poll-based hooks for detecting screen change and brute force screen capturing/comparing at their worst. At their best, they use a mirror driver like DFMirage. I&#39;m at this level. And they use something called the RFB protocol.

Microsoft Windows Remote Desktop apparently goes one step higher than VNC. I heard, from somewhere on StackOverflow, that Windows Remote Desktop doesn&#39;t send screen bitmaps, but actual drawing commands. That&#39;s quite brilliant, because it can just send simple text (draw this rectangle at this coordinate and color it with this gradient)! Remote Desktop really is pretty fast - and it&#39;s the standard way of working from home. And it uses something called the RDP protocol.

Now TeamViewer is a complete mystery to me. Apparently, they released their source code for Version 2 (TeamViewer is Version 7 as of February 2012). People have read it and said that Version 2 is useless - that it&#39;s just a few improvements over VNC with automatic NAT traversal. 

But Version 7...it&#39;s ridiculously fast now. I mean, it&#39;s actually faster than Windows Remote Desktop. I&#39;ve streamed DirectX 3D games with TeamViewer (at 1 fps, but Windows Remote Desktop doesn&#39;t even allow DirectX to run).

By the way, TeamViewer does all this *without* a mirror driver. There is an option to install one, and it gets just a bit faster.

**The Question**

**My question is, how is TeamViewer so fast?** It must not be possible. If you&#39;ve got 1920 by 1080 resolution at even 24 bit depth (16 bit depth would be noticeably ugly), thats still 6,220,800 bytes raw. Even using libjpeg-turbo (one of the fastest JPG compression libraries used by large corporations), compressing it down to 30KB (let&#39;s be extremely generous), would take time to route through TeamViewer&#39;s servers (TeamViewer bypasses corporate Symmetric NATs by simply proxying traffic through their servers). And that libjpeg-turbo compression would take time to compress. High-quality JPG compression takes 175 milliseconds for a full 1920 by 1080 screenshot for me. And that number goes up if the host&#39;s computer runs an Atom processor. I simply don&#39;t understand how TeamViewer has optimized their screen transfer so well. Again, small-size images might be highly compressed, but take at least tens of milliseconds to compress. Large-size images take no time to compress, but take a long time to get through. Somehow, TeamViewer completes this entire process to get roughly 20-25 frames per second. I&#39;ve used a network monitor, and TeamViewer is still lagless at speeds of 500 Kbps and 1 Mbps (VNC software lag for a few seconds at that transfer rate). During my `tree` Command Prompt test, TeamViewer was receiving inbound data at a rate of 1 Mbps and still running 5-6 fps. VNC and remote desktop don&#39;t do that. So, how?

The answers will be somewhat complicated and intricate, so *please don&#39;t post your $0.02 if you&#39;re only going to say it&#39;s because they use UDP instead of TCP* (would you believe they actually do use TCP just as successfully though).

I&#39;m hoping there&#39;s a TeamViewer developer somewhere here on StackOverflow.

**Potential Answers**

Will update this once people reply.

1. My thoughts are, first of all, that TeamViewer has very fine network control. For example, they split large packets to just under the MTU size and never waste a trip. They probably have all sorts of fancy hooks to detect screen changes along with extremely fast XOR image comparisons.

How is TeamViewer so fast?

I want to send only one short value in a UDP packet, but running the command

    echo -n &quot;hello&quot; | nc -4u localhost 8000

I can see that the server is getting the _hello_ stuff but I have to press &lt;kbd&gt;Ctrl&lt;/kbd&gt;+&lt;kbd&gt;c&lt;/kbd&gt; to quit the netcat command. 

How can I make it quit after sending _hello_?

---

Sorry, for the noise, I re-read the man page and found the `-q` option.

     echo -n &quot;hello&quot; | nc -4u -q1 localhost 8000

works (it quits after 1 second).

For some reason it does not work with `-q0`.

How to send only one UDP packet with netcat?

I am using multicast UDP between hosts that have multiple network interfaces.
I am using boost::asio, and am confused by the 2 operations receivers have to make: bind, then join-group.

Why do you need to specify the local address of an interface, during bind, when you do that with every multicast group that you join?

The sister-question regards the multicast port: Since during sending, you send to a multicast address &amp; port, why, during subscription to a multicast group, you only specify the address, not the port - the port being specified in the confusing call to bind.


Note: the &quot;join-group&quot; is a wrapper over `setsockopt(IP_ADD_MEMBERSHIP)`, which as documented, may be called multiple times on the same socket to subscribe to different groups (over different networks?). It would therefore make perfect sense to ditch the bind call and specify the port every time I subscribe to a group.

From what I see, always binding to &quot;0.0.0.0&quot; and specifying the interface address when joining the group, works very well. Confused.

What does it mean to bind a multicast (UDP) socket?

HTML5 websockets currently use a form of TCP communication. However, for real-time games, TCP just won&#39;t cut it (and is great reason to use some other platform, like native). As I probably need UDP to continue a project, I&#39;d like to know if the specs for HTML6 or whatever will support UDP?


Also, are there any reliable benchmarks for WebSockets that would compare the WS protocol to a  low-level, direct socket protocol?

Content Type	Original Author	Original Content on Stackoverflow
Question	user800799	View Question on Stackoverflow
Solution 1 - Sockets	Alnitak	View Answer on Stackoverflow
Solution 2 - Sockets	aMooly	View Answer on Stackoverflow

Can TCP and UDP sockets use the same port?

Sockets Problem Overview

Sockets Solutions

Solution 1 - Sockets

Solution 2 - Sockets

Selecting a row in DataGridView programmatically

$(this).serialize() -- How to add a value?

Attributions