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• Techniques for sharing a value among classes in a program

  - by Kenneth Cochran

  I'm using Environment.GetFolderPath(Environment.SpecialFolder.CommonApplicationData) + "\MyProgram" As the path to store several files used by my program. I'd like to avoid pasting the same snippet of code all over the my applcation. I need to ensure that: The path cannot be accidentally changed once its been set The classes that need it have access to it. I've considered: Making it a singleton Using constructor dependency injection Using property dependency injection Using AOP to create the path where its needed. Each has pros and cons. The singleton is everyone's favorite whipping boy. I'm not opposed to using one but there are valid reasons to avoid it if possible. I'm already heavily using constructor injection through Castle Windsor. But this is a path string and Windsor doesn't handle system type dependencies very gracefully. I could always wrap it in a class but that seems like overkill for something as simple as a passing around a string value. In any case this route would add yet another constructor argument to each class where it is used. The problem I see with property injection in this case is that there is a large amount of indirection from the where the value is set to where it is needed. I would need a very long line of middlemen to reach all the places where its used. AOP looks promising and I'm planning on using AOP for logging anyway so this at least sounds like a simple solution. Is there any other options I haven't considered? Am I off base with my evaluation of the options I have considered?

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• recvfrom returns invalid argument when *from* is passed

  - by Aditya Sehgal

  I am currently writing a small UDP server program in linux. The UDP server will receive packets from two different peers and will perform different operations based on from which peer it received the packet. I am trying to determine the source from where I receive the packet. However, when select returns and recvfrom is called, it returns with an error of Invalid Argument. If I pass NULL as the second last arguments, recvfrom succeeds. I have tried declaring fromAddr as struct sockaddr_storage, struct sockaddr_in, struct sockaddr without any success. Is their something wrong with this code? Is this the correct way to determine the source of the packet? The code snippet follows. ` /*TODO : update for TCP. use recv */ if((pkInfo->rcvLen=recvfrom(psInfo->sockFd, pkInfo->buffer, MAX_PKTSZ, 0, /* (struct sockaddr*)&fromAddr,*/ NULL, &(addrLen) )) < 0) { perror("RecvFrom failed\n"); } else { /*Apply Filter */ #if 0 struct sockaddr_in* tmpAddr; tmpAddr = (struct sockaddr_in* )&fromAddr; printf("Received Msg From %s\n",inet_ntoa(tmpAddr->sin_addr)); #endif printf("Packet Received of len = %d\n",pkInfo->rcvLen); } `

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• TCP/IP Implementation General Questions

  - by user2971023

  I've implemented the concepts shown here; http://wiki.unity3d.com/index.php/Simple_TCP/IP_Client_-_Server outside of unity and it works. (though i had to create the TCPIPServerApp from scratch as i could not find the base project anywhere). I have some general questions on how to use tcp/ip properly however. I've done some research on tcp/ip itself but I'm still a little confused. It seems like using the method above doesn't guarantee that I'll see the message (res). It just checks on every update to see if there is a different message in res. What if multiple messages are sent and the program lags or something, will i miss the earlier packet(s)? Should i instead do an array so it stores the last X messages? How do i know the data was received? Do I need to add a message id and build in my own ack into the data? Should i check to see if the port is in use before setting up a connection? Sorry for all the questions. This is all new to me but I enjoy this very much! ... Below already answered By Anton, Thanks It sounds like tcp uses its own packet numbering to ensure the packets end up in the right order on the other side. What if a packet is missed, are the subsequent packets thrown away? Or is this numbering and packet ordering, only for handling data that is broken out into multiple packets? TCP will automatically break the data into multiple packets if necessary right?

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• recvfrom() return values in Stop-and-Wait UDP?

  - by mavErick

  I am trying to implement a Stop-and-Wait UDP client-server socket program in C. As known, there are basically three possible scenarios for Stop-and-Wait flow control. i.e., After transmitting a packet, the sender receives a correct ACK and thus starts transmitting the next packet; the sender receives an incorrect ACK and thus retransmits this packet; the sender receives no ACK within a TIMEOUT and thus retransmits this packet. My idea is to differentiate these three scenarios with the return value of recvfrom() on the sender side. For scenario 1&2: recvfrom() just returns the length of the received ACK. Since in my implementation the incorrect ACK is of the same length of the correct one, so I will have to go deeper and check the contents of the ACK. It's not a big deal. I know how to do. Problems come when I am trying to recognize scenario 3 where no ACK is received. What confuses me is that my recvfrom() is within a while loop, so the recvfrom() will be called constantly. What will it return when the receiver is not actually sending the sender ACK? Is it 0 or 1?

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• New <%: %> Syntax for HTML Encoding Output in ASP.NET 4 (and ASP.NET MVC 2)

  - by ScottGu

  [In addition to blogging, I am also now using Twitter for quick updates and to share links. Follow me at: twitter.com/scottgu] This is the nineteenth in a series of blog posts I’m doing on the upcoming VS 2010 and .NET 4 release. Today’s post covers a small, but very useful, new syntax feature being introduced with ASP.NET 4 – which is the ability to automatically HTML encode output within code nuggets.  This helps protect your applications and sites against cross-site script injection (XSS) and HTML injection attacks, and enables you to do so using a nice concise syntax. HTML Encoding Cross-site script injection (XSS) and HTML encoding attacks are two of the most common security issues that plague web-sites and applications.  They occur when hackers find a way to inject client-side script or HTML markup into web-pages that are then viewed by other visitors to a site.  This can be used to both vandalize a site, as well as enable hackers to run client-script code that steals cookie data and/or exploits a user’s identity on a site to do bad things. One way to help mitigate against cross-site scripting attacks is to make sure that rendered output is HTML encoded within a page.  This helps ensures that any content that might have been input/modified by an end-user cannot be output back onto a page containing tags like <script> or <img> elements.  ASP.NET applications (especially those using ASP.NET MVC) often rely on using <%= %> code-nugget expressions to render output.  Developers today often use the Server.HtmlEncode() or HttpUtility.Encode() helper methods within these expressions to HTML encode the output before it is rendered.  This can be done using code like below: While this works fine, there are two downsides of it: It is a little verbose Developers often forget to call the HtmlEncode method New <%: %> Code Nugget Syntax With ASP.NET 4 we are introducing a new code expression syntax (<%:  %>) that renders output like <%= %> blocks do – but which also automatically HTML encodes it before doing so.  This eliminates the need to explicitly HTML encode content like we did in the example above.  Instead you can just write the more concise code below to accomplish the same thing: We chose the <%: %> syntax so that it would be easy to quickly replace existing instances of <%= %> code blocks.  It also enables you to easily search your code-base for <%= %> elements to find and verify any cases where you are not using HTML encoding within your application to ensure that you have the correct behavior. Avoiding Double Encoding While HTML encoding content is often a good best practice, there are times when the content you are outputting is meant to be HTML or is already encoded – in which case you don’t want to HTML encode it again.  ASP.NET 4 introduces a new IHtmlString interface (along with a concrete implementation: HtmlString) that you can implement on types to indicate that its value is already properly encoded (or otherwise examined) for displaying as HTML, and that therefore the value should not be HTML-encoded again.  The <%: %> code-nugget syntax checks for the presence of the IHtmlString interface and will not HTML encode the output of the code expression if its value implements this interface.  This allows developers to avoid having to decide on a per-case basis whether to use <%= %> or <%: %> code-nuggets.  Instead you can always use <%: %> code nuggets, and then have any properties or data-types that are already HTML encoded implement the IHtmlString interface. Using ASP.NET MVC HTML Helper Methods with <%: %> For a practical example of where this HTML encoding escape mechanism is useful, consider scenarios where you use HTML helper methods with ASP.NET MVC.  These helper methods typically return HTML.  For example: the Html.TextBox() helper method returns markup like <input type=”text”/>.  With ASP.NET MVC 2 these helper methods now by default return HtmlString types – which indicates that the returned string content is safe for rendering and should not be encoded by <%: %> nuggets.  This allows you to use these methods within both <%= %> code nugget blocks: As well as within <%: %> code nugget blocks: In both cases above the HTML content returned from the helper method will be rendered to the client as HTML – and the <%: %> code nugget will avoid double-encoding it. This enables you to default to always using <%: %> code nuggets instead of <%= %> code blocks within your applications.  If you want to be really hardcore you can even create a build rule that searches your application looking for <%= %> usages and flags any cases it finds as an error to enforce that HTML encoding always takes place. Scaffolding ASP.NET MVC 2 Views When you use VS 2010 (or the free Visual Web Developer 2010 Express) you’ll find that the views that are scaffolded using the “Add View” dialog now by default always use <%: %> blocks when outputting any content.  For example, below I’ve scaffolded a simple “Edit” view for an article object.  Note the three usages of <%: %> code nuggets for the label, textbox, and validation message (all output with HTML helper methods): Summary The new <%: %> syntax provides a concise way to automatically HTML encode content and then render it as output.  It allows you to make your code a little less verbose, and to easily check/verify that you are always HTML encoding content throughout your site.  This can help protect your applications against cross-site script injection (XSS) and HTML injection attacks.  Hope this helps, Scott

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• C# .Net 3.5 Asynchronous Socket Server Performance Problem

  - by iBrAaAa

  I'm developing an Asynchronous Game Server using .Net Socket Asynchronous Model( BeginAccept/EndAccept...etc.) The problem I'm facing is described like that: When I have only one client connected, the server response time is very fast but once a second client connects, the server response time increases too much. I've measured the time from a client sends a message to the server until it gets the reply in both cases. I found that the average time in case of one client is about 17ms and in case of 2 clients about 280ms!!! What I really see is that: When 2 clients are connected and only one of them is moving(i.e. requesting service from the server) it is equivalently equal to the case when only one client is connected(i.e. fast response). However, when the 2 clients move at the same time(i.e. requests service from the server at the same time) their motion becomes very slow (as if the server replies each one of them in order i.e. not simultaneously). Basically, what I am doing is that: When a client requests a permission for motion from the server and the server grants him the request, the server then broadcasts the new position of the client to all the players. So if two clients are moving in the same time, the server is eventually trying to broadcast to both clients the new position of each of them at the same time. EX: Client1 asks to go to position (2,2) Client2 asks to go to position (5,5) Server sends to each of Client1 & Client2 the same two messages: message1: "Client1 at (2,2)" message2: "Client2 at (5,5)" I believe that the problem comes from the fact that Socket class is thread safe according MSDN documentation http://msdn.microsoft.com/en-us/library/system.net.sockets.socket.aspx. (NOT SURE THAT IT IS THE PROBLEM) Below is the code for the server: /// /// This class is responsible for handling packet receiving and sending /// public class NetworkManager { /// /// An integer to hold the server port number to be used for the connections. Its default value is 5000. /// private readonly int port = 5000; /// /// hashtable contain all the clients connected to the server. /// key: player Id /// value: socket /// private readonly Hashtable connectedClients = new Hashtable(); /// /// An event to hold the thread to wait for a new client /// private readonly ManualResetEvent resetEvent = new ManualResetEvent(false); /// /// keeps track of the number of the connected clients /// private int clientCount; /// /// The socket of the server at which the clients connect /// private readonly Socket mainSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp); /// /// The socket exception that informs that a client is disconnected /// private const int ClientDisconnectedErrorCode = 10054; /// /// The only instance of this class. /// private static readonly NetworkManager networkManagerInstance = new NetworkManager(); /// /// A delegate for the new client connected event. /// /// the sender object /// the event args public delegate void NewClientConnected(Object sender, SystemEventArgs e); /// /// A delegate for the position update message reception. /// /// the sender object /// the event args public delegate void PositionUpdateMessageRecieved(Object sender, PositionUpdateEventArgs e); /// /// The event which fires when a client sends a position message /// public PositionUpdateMessageRecieved PositionUpdateMessageEvent { get; set; } /// /// keeps track of the number of the connected clients /// public int ClientCount { get { return clientCount; } } /// /// A getter for this class instance. /// /// only instance. public static NetworkManager NetworkManagerInstance { get { return networkManagerInstance; } } private NetworkManager() {} /// Starts the game server and holds this thread alive /// public void StartServer() { //Bind the mainSocket to the server IP address and port mainSocket.Bind(new IPEndPoint(IPAddress.Any, port)); //The server starts to listen on the binded socket with max connection queue //1024 mainSocket.Listen(1024); //Start accepting clients asynchronously mainSocket.BeginAccept(OnClientConnected, null); //Wait until there is a client wants to connect resetEvent.WaitOne(); } /// /// Receives connections of new clients and fire the NewClientConnected event /// private void OnClientConnected(IAsyncResult asyncResult) { Interlocked.Increment(ref clientCount); ClientInfo newClient = new ClientInfo { WorkerSocket = mainSocket.EndAccept(asyncResult), PlayerId = clientCount }; //Add the new client to the hashtable and increment the number of clients connectedClients.Add(newClient.PlayerId, newClient); //fire the new client event informing that a new client is connected to the server if (NewClientEvent != null) { NewClientEvent(this, System.EventArgs.Empty); } newClient.WorkerSocket.BeginReceive(newClient.Buffer, 0, BasePacket.GetMaxPacketSize(), SocketFlags.None, new AsyncCallback(WaitForData), newClient); //Start accepting clients asynchronously again mainSocket.BeginAccept(OnClientConnected, null); } /// Waits for the upcoming messages from different clients and fires the proper event according to the packet type. /// /// private void WaitForData(IAsyncResult asyncResult) { ClientInfo sendingClient = null; try { //Take the client information from the asynchronous result resulting from the BeginReceive sendingClient = asyncResult.AsyncState as ClientInfo; // If client is disconnected, then throw a socket exception // with the correct error code. if (!IsConnected(sendingClient.WorkerSocket)) { throw new SocketException(ClientDisconnectedErrorCode); } //End the pending receive request sendingClient.WorkerSocket.EndReceive(asyncResult); //Fire the appropriate event FireMessageTypeEvent(sendingClient.ConvertBytesToPacket() as BasePacket); // Begin receiving data from this client sendingClient.WorkerSocket.BeginReceive(sendingClient.Buffer, 0, BasePacket.GetMaxPacketSize(), SocketFlags.None, new AsyncCallback(WaitForData), sendingClient); } catch (SocketException e) { if (e.ErrorCode == ClientDisconnectedErrorCode) { // Close the socket. if (sendingClient.WorkerSocket != null) { sendingClient.WorkerSocket.Close(); sendingClient.WorkerSocket = null; } // Remove it from the hash table. connectedClients.Remove(sendingClient.PlayerId); if (ClientDisconnectedEvent != null) { ClientDisconnectedEvent(this, new ClientDisconnectedEventArgs(sendingClient.PlayerId)); } } } catch (Exception e) { // Begin receiving data from this client sendingClient.WorkerSocket.BeginReceive(sendingClient.Buffer, 0, BasePacket.GetMaxPacketSize(), SocketFlags.None, new AsyncCallback(WaitForData), sendingClient); } } /// /// Broadcasts the input message to all the connected clients /// /// public void BroadcastMessage(BasePacket message) { byte[] bytes = message.ConvertToBytes(); foreach (ClientInfo client in connectedClients.Values) { client.WorkerSocket.BeginSend(bytes, 0, bytes.Length, SocketFlags.None, SendAsync, client); } } /// /// Sends the input message to the client specified by his ID. /// /// /// The message to be sent. /// The id of the client to receive the message. public void SendToClient(BasePacket message, int id) { byte[] bytes = message.ConvertToBytes(); (connectedClients[id] as ClientInfo).WorkerSocket.BeginSend(bytes, 0, bytes.Length, SocketFlags.None, SendAsync, connectedClients[id]); } private void SendAsync(IAsyncResult asyncResult) { ClientInfo currentClient = (ClientInfo)asyncResult.AsyncState; currentClient.WorkerSocket.EndSend(asyncResult); } /// Fires the event depending on the type of received packet /// /// The received packet. void FireMessageTypeEvent(BasePacket packet) { switch (packet.MessageType) { case MessageType.PositionUpdateMessage: if (PositionUpdateMessageEvent != null) { PositionUpdateMessageEvent(this, new PositionUpdateEventArgs(packet as PositionUpdatePacket)); } break; } } } The events fired are handled in a different class, here are the event handling code for the PositionUpdateMessage (Other handlers are irrelevant): private readonly Hashtable onlinePlayers = new Hashtable(); /// /// Constructor that creates a new instance of the GameController class. /// private GameController() { //Start the server server = new Thread(networkManager.StartServer); server.Start(); //Create an event handler for the NewClientEvent of networkManager networkManager.PositionUpdateMessageEvent += OnPositionUpdateMessageReceived; } /// /// this event handler is called when a client asks for movement. /// private void OnPositionUpdateMessageReceived(object sender, PositionUpdateEventArgs e) { Point currentLocation = ((PlayerData)onlinePlayers[e.PositionUpdatePacket.PlayerId]).Position; Point locationRequested = e.PositionUpdatePacket.Position; ((PlayerData)onlinePlayers[e.PositionUpdatePacket.PlayerId]).Position = locationRequested; // Broadcast the new position networkManager.BroadcastMessage(new PositionUpdatePacket { Position = locationRequested, PlayerId = e.PositionUpdatePacket.PlayerId }); }

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• Delphi hook to redirect to different ip

  - by Chris

  What is the best way to redirect ANY browser to a different ip for specific sites? For example if the user will type www.facebook.com in any browser he will be redirected to 127.0.0.1. Also the same should happen if he will type 66.220.146.11. What I have until now is this: using the winpkfilter I am able to intercept all the traffic on port 80, with type(in or out), source ip, destination ip and packet. My problem is to modify somehow the packet so the browser will be redirected. This is the code that i have right now: program Pass; {$APPTYPE CONSOLE} uses SysUtils, Windows, Winsock, winpkf, iphlp; var iIndex, counter : DWORD; hFilt : THANDLE; Adapts : TCP_AdapterList; AdapterMode : ADAPTER_MODE; Buffer, ParsedBuffer : INTERMEDIATE_BUFFER; ReadRequest : ETH_REQUEST; hEvent : THANDLE; hAdapter : THANDLE; pEtherHeader : TEtherHeaderPtr; pIPHeader : TIPHeaderPtr; pTcpHeader : TTCPHeaderPtr; pUdpHeader : TUDPHeaderPtr; SourceIP, DestIP : TInAddr; thePacket : PChar; f : TextFile; SourceIpString, DestinationIpString : string; SourceName, DestinationName : string; function IPAddrToName(IPAddr : string) : string; var SockAddrIn : TSockAddrIn; HostEnt : PHostEnt; WSAData : TWSAData; begin WSAStartup($101, WSAData); SockAddrIn.sin_addr.s_addr := inet_addr(PChar(IPAddr)); HostEnt := gethostbyaddr(@SockAddrIn.sin_addr.S_addr, 4, AF_INET); if HostEnt < nil then begin result := StrPas(Hostent^.h_name) end else begin result := ''; end; end; procedure ReleaseInterface(); begin // Restore default mode AdapterMode.dwFlags := 0; AdapterMode.hAdapterHandle := hAdapter; SetAdapterMode(hFilt, @AdapterMode); // Set NULL event to release previously set event object SetPacketEvent(hFilt, hAdapter, 0); // Close Event if hEvent < 0 then CloseHandle(hEvent); // Close driver object CloseFilterDriver(hFilt); // Release NDISAPI FreeNDISAPI(); end; begin // Check the number of parameters if ParamCount() < 2 then begin Writeln('Command line syntax:'); Writeln(' PassThru.exe index num'); Writeln(' index - network interface index.'); Writeln(' num - number or packets to filter'); Writeln('You can use ListAdapters to determine correct index.'); Exit; end; // Initialize NDISAPI InitNDISAPI(); // Create driver object hFilt := OpenFilterDriver('NDISRD'); if IsDriverLoaded(hFilt) then begin // Get parameters from command line iIndex := StrToInt(ParamStr(1)); counter := StrToInt(ParamStr(2)); // Set exit procedure ExitProcessProc := ReleaseInterface; // Get TCP/IP bound interfaces GetTcpipBoundAdaptersInfo(hFilt, @Adapts); // Check paramer values if iIndex > Adapts.m_nAdapterCount then begin Writeln('There is no network interface with such index on this system.'); Exit; end; hAdapter := Adapts.m_nAdapterHandle[iIndex]; AdapterMode.dwFlags := MSTCP_FLAG_SENT_TUNNEL or MSTCP_FLAG_RECV_TUNNEL; AdapterMode.hAdapterHandle := hAdapter; // Create notification event hEvent := CreateEvent(nil, TRUE, FALSE, nil); if hEvent <> 0 then if SetPacketEvent(hFilt, hAdapter, hEvent) <> 0 then begin // Initialize request ReadRequest.EthPacket.Buffer := @Buffer; ReadRequest.hAdapterHandle := hAdapter; SetAdapterMode(hFilt, @AdapterMode); counter := 0; //while counter <> 0 do while true do begin WaitForSingleObject(hEvent, INFINITE); while ReadPacket(hFilt, @ReadRequest) <> 0 do begin //dec(counter); pEtherHeader := TEtherHeaderPtr(@Buffer.m_IBuffer); if ntohs(pEtherHeader.h_proto) = ETH_P_IP then begin pIPHeader := TIPHeaderPtr(Integer(pEtherHeader) + SizeOf(TEtherHeader)); SourceIP.S_addr := pIPHeader.SourceIp; DestIP.S_addr := pIPHeader.DestIp; if pIPHeader.Protocol = IPPROTO_TCP then begin pTcpHeader := TTCPHeaderPtr(Integer(pIPHeader) + (pIPHeader.VerLen and $F) * 4); if (pTcpHeader.SourcePort = htons(80)) or (pTcpHeader.DestPort = htons(80)) then begin inc(counter); if Buffer.m_dwDeviceFlags = PACKET_FLAG_ON_SEND then Writeln(counter, ') - MSTCP --> Interface') else Writeln(counter, ') - Interface --> MSTCP'); Writeln(' Packet size = ', Buffer.m_Length); Writeln(Format(' IP %.3u.%.3u.%.3u.%.3u --> %.3u.%.3u.%.3u.%.3u PROTOCOL: %u', [byte(SourceIP.S_un_b.s_b1), byte(SourceIP.S_un_b.s_b2), byte(SourceIP.S_un_b.s_b3), byte(SourceIP.S_un_b.s_b4), byte(DestIP.S_un_b.s_b1), byte(DestIP.S_un_b.s_b2), byte(DestIP.S_un_b.s_b3), byte(DestIP.S_un_b.s_b4), byte(pIPHeader.Protocol)] )); Writeln(Format(' TCP SRC PORT: %d DST PORT: %d', [ntohs(pTcpHeader.SourcePort), ntohs(pTcpHeader.DestPort)])); //get the data thePacket := pchar(pEtherHeader) + (sizeof(TEtherHeaderPtr) + pIpHeader.VerLen * 4 + pTcpHeader.Offset * 4); { SourceIpString := IntToStr(byte(SourceIP.S_un_b.s_b1)) + '.' + IntToStr(byte(SourceIP.S_un_b.s_b2)) + '.' + IntToStr(byte(SourceIP.S_un_b.s_b3)) + '.' + IntToStr(byte(SourceIP.S_un_b.s_b4)); DestinationIpString := IntToStr(byte(DestIP.S_un_b.s_b1)) + '.' + IntToStr(byte(DestIP.S_un_b.s_b2)) + '.' + IntToStr(byte(DestIP.S_un_b.s_b3)) + '.' + IntToStr(byte(DestIP.S_un_b.s_b4)); } end; end; end; // if ntohs(pEtherHeader.h_proto) = ETH_P_RARP then // Writeln(' Reverse Addr Res packet'); // if ntohs(pEtherHeader.h_proto) = ETH_P_ARP then // Writeln(' Address Resolution packet'); //Writeln('__'); if Buffer.m_dwDeviceFlags = PACKET_FLAG_ON_SEND then // Place packet on the network interface SendPacketToAdapter(hFilt, @ReadRequest) else // Indicate packet to MSTCP SendPacketToMstcp(hFilt, @ReadRequest); { if counter = 0 then begin Writeln('Filtering complete'); readln; break; end; } end; ResetEvent(hEvent); end; end; end; end.

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• .Net 3.5 Asynchronous Socket Server Performance Problem

  - by iBrAaAa

  I'm developing an Asynchronous Game Server using .Net Socket Asynchronous Model( BeginAccept/EndAccept...etc.) The problem I'm facing is described like that: When I have only one client connected, the server response time is very fast but once a second client connects, the server response time increases too much. I've measured the time from a client sends a message to the server until it gets the reply in both cases. I found that the average time in case of one client is about 17ms and in case of 2 clients about 280ms!!! What I really see is that: When 2 clients are connected and only one of them is moving(i.e. requesting service from the server) it is equivalently equal to the case when only one client is connected(i.e. fast response). However, when the 2 clients move at the same time(i.e. requests service from the server at the same time) their motion becomes very slow (as if the server replies each one of them in order i.e. not simultaneously). Basically, what I am doing is that: When a client requests a permission for motion from the server and the server grants him the request, the server then broadcasts the new position of the client to all the players. So if two clients are moving in the same time, the server is eventually trying to broadcast to both clients the new position of each of them at the same time. EX: Client1 asks to go to position (2,2) Client2 asks to go to position (5,5) Server sends to each of Client1 & Client2 the same two messages: message1: "Client1 at (2,2)" message2: "Client2 at (5,5)" I believe that the problem comes from the fact that Socket class is thread safe according MSDN documentation http://msdn.microsoft.com/en-us/library/system.net.sockets.socket.aspx. (NOT SURE THAT IT IS THE PROBLEM) Below is the code for the server: /// /// This class is responsible for handling packet receiving and sending /// public class NetworkManager { /// /// An integer to hold the server port number to be used for the connections. Its default value is 5000. /// private readonly int port = 5000; /// /// hashtable contain all the clients connected to the server. /// key: player Id /// value: socket /// private readonly Hashtable connectedClients = new Hashtable(); /// /// An event to hold the thread to wait for a new client /// private readonly ManualResetEvent resetEvent = new ManualResetEvent(false); /// /// keeps track of the number of the connected clients /// private int clientCount; /// /// The socket of the server at which the clients connect /// private readonly Socket mainSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp); /// /// The socket exception that informs that a client is disconnected /// private const int ClientDisconnectedErrorCode = 10054; /// /// The only instance of this class. /// private static readonly NetworkManager networkManagerInstance = new NetworkManager(); /// /// A delegate for the new client connected event. /// /// the sender object /// the event args public delegate void NewClientConnected(Object sender, SystemEventArgs e); /// /// A delegate for the position update message reception. /// /// the sender object /// the event args public delegate void PositionUpdateMessageRecieved(Object sender, PositionUpdateEventArgs e); /// /// The event which fires when a client sends a position message /// public PositionUpdateMessageRecieved PositionUpdateMessageEvent { get; set; } /// /// keeps track of the number of the connected clients /// public int ClientCount { get { return clientCount; } } /// /// A getter for this class instance. /// /// only instance. public static NetworkManager NetworkManagerInstance { get { return networkManagerInstance; } } private NetworkManager() {} /// Starts the game server and holds this thread alive /// public void StartServer() { //Bind the mainSocket to the server IP address and port mainSocket.Bind(new IPEndPoint(IPAddress.Any, port)); //The server starts to listen on the binded socket with max connection queue //1024 mainSocket.Listen(1024); //Start accepting clients asynchronously mainSocket.BeginAccept(OnClientConnected, null); //Wait until there is a client wants to connect resetEvent.WaitOne(); } /// /// Receives connections of new clients and fire the NewClientConnected event /// private void OnClientConnected(IAsyncResult asyncResult) { Interlocked.Increment(ref clientCount); ClientInfo newClient = new ClientInfo { WorkerSocket = mainSocket.EndAccept(asyncResult), PlayerId = clientCount }; //Add the new client to the hashtable and increment the number of clients connectedClients.Add(newClient.PlayerId, newClient); //fire the new client event informing that a new client is connected to the server if (NewClientEvent != null) { NewClientEvent(this, System.EventArgs.Empty); } newClient.WorkerSocket.BeginReceive(newClient.Buffer, 0, BasePacket.GetMaxPacketSize(), SocketFlags.None, new AsyncCallback(WaitForData), newClient); //Start accepting clients asynchronously again mainSocket.BeginAccept(OnClientConnected, null); } /// Waits for the upcoming messages from different clients and fires the proper event according to the packet type. /// /// private void WaitForData(IAsyncResult asyncResult) { ClientInfo sendingClient = null; try { //Take the client information from the asynchronous result resulting from the BeginReceive sendingClient = asyncResult.AsyncState as ClientInfo; // If client is disconnected, then throw a socket exception // with the correct error code. if (!IsConnected(sendingClient.WorkerSocket)) { throw new SocketException(ClientDisconnectedErrorCode); } //End the pending receive request sendingClient.WorkerSocket.EndReceive(asyncResult); //Fire the appropriate event FireMessageTypeEvent(sendingClient.ConvertBytesToPacket() as BasePacket); // Begin receiving data from this client sendingClient.WorkerSocket.BeginReceive(sendingClient.Buffer, 0, BasePacket.GetMaxPacketSize(), SocketFlags.None, new AsyncCallback(WaitForData), sendingClient); } catch (SocketException e) { if (e.ErrorCode == ClientDisconnectedErrorCode) { // Close the socket. if (sendingClient.WorkerSocket != null) { sendingClient.WorkerSocket.Close(); sendingClient.WorkerSocket = null; } // Remove it from the hash table. connectedClients.Remove(sendingClient.PlayerId); if (ClientDisconnectedEvent != null) { ClientDisconnectedEvent(this, new ClientDisconnectedEventArgs(sendingClient.PlayerId)); } } } catch (Exception e) { // Begin receiving data from this client sendingClient.WorkerSocket.BeginReceive(sendingClient.Buffer, 0, BasePacket.GetMaxPacketSize(), SocketFlags.None, new AsyncCallback(WaitForData), sendingClient); } } /// /// Broadcasts the input message to all the connected clients /// /// public void BroadcastMessage(BasePacket message) { byte[] bytes = message.ConvertToBytes(); foreach (ClientInfo client in connectedClients.Values) { client.WorkerSocket.BeginSend(bytes, 0, bytes.Length, SocketFlags.None, SendAsync, client); } } /// /// Sends the input message to the client specified by his ID. /// /// /// The message to be sent. /// The id of the client to receive the message. public void SendToClient(BasePacket message, int id) { byte[] bytes = message.ConvertToBytes(); (connectedClients[id] as ClientInfo).WorkerSocket.BeginSend(bytes, 0, bytes.Length, SocketFlags.None, SendAsync, connectedClients[id]); } private void SendAsync(IAsyncResult asyncResult) { ClientInfo currentClient = (ClientInfo)asyncResult.AsyncState; currentClient.WorkerSocket.EndSend(asyncResult); } /// Fires the event depending on the type of received packet /// /// The received packet. void FireMessageTypeEvent(BasePacket packet) { switch (packet.MessageType) { case MessageType.PositionUpdateMessage: if (PositionUpdateMessageEvent != null) { PositionUpdateMessageEvent(this, new PositionUpdateEventArgs(packet as PositionUpdatePacket)); } break; } } } The events fired are handled in a different class, here are the event handling code for the PositionUpdateMessage (Other handlers are irrelevant): private readonly Hashtable onlinePlayers = new Hashtable(); /// /// Constructor that creates a new instance of the GameController class. /// private GameController() { //Start the server server = new Thread(networkManager.StartServer); server.Start(); //Create an event handler for the NewClientEvent of networkManager networkManager.PositionUpdateMessageEvent += OnPositionUpdateMessageReceived; } /// /// this event handler is called when a client asks for movement. /// private void OnPositionUpdateMessageReceived(object sender, PositionUpdateEventArgs e) { Point currentLocation = ((PlayerData)onlinePlayers[e.PositionUpdatePacket.PlayerId]).Position; Point locationRequested = e.PositionUpdatePacket.Position; ((PlayerData)onlinePlayers[e.PositionUpdatePacket.PlayerId]).Position = locationRequested; // Broadcast the new position networkManager.BroadcastMessage(new PositionUpdatePacket { Position = locationRequested, PlayerId = e.PositionUpdatePacket.PlayerId }); }

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• Wireless Connected But No Internet Connection (Ubuntu 12.04)

  - by Zxy

  I am using same network for 2 days and everything was normal. However, today even though it shows me as connected to the network, I do not have internet connection. If I use ethernet cable instead of wireless, I am still able to connect to the internet. Also my friends are able to connect to the wireless network and they can get internet connection. I did not update or install anything since yesterday. Therefore I do not have any idea why it is happening. Here is some information about my connection: I will be appreciate to any kind of help. root@ghostrider:/etc/resolvconf# ping 127.0.0.1 PING 127.0.0.1 (127.0.0.1) 56(84) bytes of data. 64 bytes from 127.0.0.1: icmp_req=1 ttl=64 time=0.042 ms 64 bytes from 127.0.0.1: icmp_req=2 ttl=64 time=0.023 ms 64 bytes from 127.0.0.1: icmp_req=3 ttl=64 time=0.036 ms 64 bytes from 127.0.0.1: icmp_req=4 ttl=64 time=0.040 ms ^C --- 127.0.0.1 ping statistics --- 4 packets transmitted, 4 received, 0% packet loss, time 2998ms rtt min/avg/max/mdev = 0.023/0.035/0.042/0.008 ms root@ghostrider:/etc/resolvconf# ping 192.168.1.3 PING 192.168.1.3 (192.168.1.3) 56(84) bytes of data. ^C --- 192.168.1.3 ping statistics --- 19 packets transmitted, 0 received, 100% packet loss, time 18143ms root@ghostrider:/etc/resolvconf# ping 8.8.8.8 PING 8.8.8.8 (8.8.8.8) 56(84) bytes of data. ^C --- 8.8.8.8 ping statistics --- 11 packets transmitted, 0 received, 100% packet loss, time 10079ms root@ghostrider:/etc/resolvconf# cat /etc/lsb-release; uname -a DISTRIB_ID=Ubuntu DISTRIB_RELEASE=12.04 DISTRIB_CODENAME=precise DISTRIB_DESCRIPTION="Ubuntu 12.04 LTS" Linux ghostrider 3.2.0-24-generic-pae #39-Ubuntu SMP Mon May 21 18:54:21 UTC 2012 i686 i686 i386 GNU/Linux root@ghostrider:/etc/resolvconf# lspci -nnk | grep -iA2 net 03:00.0 Ethernet controller [0200]: Atheros Communications Inc. AR8131 Gigabit Ethernet [1969:1063] (rev c0) Subsystem: Lenovo Device [17aa:3956] Kernel driver in use: atl1c -- 04:00.0 Network controller [0280]: Broadcom Corporation BCM4313 802.11b/g/n Wireless LAN Controller [14e4:4727] (rev 01) Subsystem: Broadcom Corporation Device [14e4:0510] Kernel driver in use: wl root@ghostrider:/etc/resolvconf# lsusb Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 001 Device 002: ID 8087:0020 Intel Corp. Integrated Rate Matching Hub Bus 002 Device 002: ID 8087:0020 Intel Corp. Integrated Rate Matching Hub Bus 001 Device 007: ID 0489:e00d Foxconn / Hon Hai Bus 001 Device 004: ID 1c7a:0801 LighTuning Technology Inc. Fingerprint Reader Bus 001 Device 005: ID 064e:f219 Suyin Corp. Bus 002 Device 010: ID 0424:2412 Standard Microsystems Corp. Bus 002 Device 004: ID 046d:c52b Logitech, Inc. Unifying Receiver Bus 002 Device 011: ID 0403:6010 Future Technology Devices International, Ltd FT2232C Dual USB-UART/FIFO IC root@ghostrider:/etc/resolvconf# iwconfig lo no wireless extensions. eth1 IEEE 802.11 ESSID:"PoliTekno" Mode:Managed Frequency:2.462 GHz Access Point: 00:16:E3:40:C3:E4 Bit Rate=54 Mb/s Tx-Power:24 dBm Retry min limit:7 RTS thr:off Fragment thr:off Power Management:off Link Quality=5/5 Signal level=-52 dBm Noise level=-97 dBm Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0 Tx excessive retries:0 Invalid misc:0 Missed beacon:0 eth0 no wireless extensions. root@ghostrider:/etc/resolvconf# rfkill list all 0: brcmwl-0: Wireless LAN Soft blocked: no Hard blocked: no 1: ideapad_wlan: Wireless LAN Soft blocked: no Hard blocked: no 2: ideapad_bluetooth: Bluetooth Soft blocked: no Hard blocked: no 5: hci0: Bluetooth Soft blocked: no Hard blocked: no root@ghostrider:/etc/resolvconf# lsmod Module Size Used by nls_iso8859_1 12617 0 nls_cp437 12751 0 vfat 17308 0 fat 55605 1 vfat usb_storage 39646 0 uas 17828 0 snd_hda_codec_realtek 174055 1 rfcomm 38139 12 parport_pc 32114 0 ppdev 12849 0 bnep 17830 2 joydev 17393 0 ftdi_sio 35859 1 usbserial 37173 3 ftdi_sio snd_hda_intel 32765 3 snd_hda_codec 109562 2 snd_hda_codec_realtek,snd_hda_intel snd_hwdep 13276 1 snd_hda_codec acer_wmi 23612 0 hid_logitech_dj 18177 0 snd_pcm 80845 2 snd_hda_intel,snd_hda_codec uvcvideo 67203 0 btusb 17912 2 snd_seq_midi 13132 0 videodev 86588 1 uvcvideo bluetooth 158438 23 rfcomm,bnep,btusb psmouse 72919 0 usbhid 41906 1 hid_logitech_dj snd_rawmidi 25424 1 snd_seq_midi intel_ips 17753 0 serio_raw 13027 0 root@ghostrider:/etc/resolvconf# ping 127.0.0.1 PING 127.0.0.1 (127.0.0.1) 56(84) bytes of data. 64 bytes from 127.0.0.1: icmp_req=1 ttl=64 time=0.042 ms 64 bytes from 127.0.0.1: icmp_req=2 ttl=64 time=0.023 ms 64 bytes from 127.0.0.1: icmp_req=3 ttl=64 time=0.036 ms 64 bytes from 127.0.0.1: icmp_req=4 ttl=64 time=0.040 ms ^C --- 127.0.0.1 ping statistics --- 4 packets transmitted, 4 received, 0% packet loss, time 2998ms rtt min/avg/max/mdev = 0.023/0.035/0.042/0.008 ms root@ghostrider:/etc/resolvconf# ping 192.168.1.3 PING 192.168.1.3 (192.168.1.3) 56(84) bytes of data. ^C --- 192.168.1.3 ping statistics --- 19 packets transmitted, 0 received, 100% packet loss, time 18143ms root@ghostrider:/etc/resolvconf# ping 8.8.8.8 PING 8.8.8.8 (8.8.8.8) 56(84) bytes of data. ^C --- 8.8.8.8 ping statistics --- 11 packets transmitted, 0 received, 100% packet loss, time 10079ms root@ghostrider:/etc/resolvconf# cat /etc/lsb-release; uname -a DISTRIB_ID=Ubuntu DISTRIB_RELEASE=12.04 DISTRIB_CODENAME=precise DISTRIB_DESCRIPTION="Ubuntu 12.04 LTS" Linux ghostrider 3.2.0-24-generic-pae #39-Ubuntu SMP Mon May 21 18:54:21 UTC 2012 i686 i686 i386 GNU/Linux root@ghostrider:/etc/resolvconf# lspci -nnk | grep -iA2 net 03:00.0 Ethernet controller [0200]: Atheros Communications Inc. AR8131 Gigabit Ethernet [1969:1063] (rev c0) Subsystem: Lenovo Device [17aa:3956] Kernel driver in use: atl1c -- 04:00.0 Network controller [0280]: Broadcom Corporation BCM4313 802.11b/g/n Wireless LAN Controller [14e4:4727] (rev 01) Subsystem: Broadcom Corporation Device [14e4:0510] Kernel driver in use: wl root@ghostrider:/etc/resolvconf# lsusb Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 001 Device 002: ID 8087:0020 Intel Corp. Integrated Rate Matching Hub Bus 002 Device 002: ID 8087:0020 Intel Corp. Integrated Rate Matching Hub Bus 001 Device 007: ID 0489:e00d Foxconn / Hon Hai Bus 001 Device 004: ID 1c7a:0801 LighTuning Technology Inc. Fingerprint Reader Bus 001 Device 005: ID 064e:f219 Suyin Corp. Bus 002 Device 010: ID 0424:2412 Standard Microsystems Corp. Bus 002 Device 004: ID 046d:c52b Logitech, Inc. Unifying Receiver Bus 002 Device 011: ID 0403:6010 Future Technology Devices International, Ltd FT2232C Dual USB-UART/FIFO IC root@ghostrider:/etc/resolvconf# iwconfig lo no wireless extensions. eth1 IEEE 802.11 ESSID:"PoliTekno" Mode:Managed Frequency:2.462 GHz Access Point: 00:16:E3:40:C3:E4 Bit Rate=54 Mb/s Tx-Power:24 dBm Retry min limit:7 RTS thr:off Fragment thr:off Power Management:off Link Quality=5/5 Signal level=-52 dBm Noise level=-97 dBm Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0 Tx excessive retries:0 Invalid misc:0 Missed beacon:0 eth0 no wireless extensions. root@ghostrider:/etc/resolvconf# rfkill list all 0: brcmwl-0: Wireless LAN Soft blocked: no Hard blocked: no 1: ideapad_wlan: Wireless LAN Soft blocked: no Hard blocked: no 2: ideapad_bluetooth: Bluetooth Soft blocked: no Hard blocked: no 5: hci0: Bluetooth Soft blocked: no Hard blocked: no root@ghostrider:/etc/resolvconf# lsmod Module Size Used by nls_iso8859_1 12617 0 nls_cp437 12751 0 vfat 17308 0 fat 55605 1 vfat usb_storage 39646 0 uas 17828 0 snd_hda_codec_realtek 174055 1 rfcomm 38139 12 parport_pc 32114 0 ppdev 12849 0 bnep 17830 2 joydev 17393 0 ftdi_sio 35859 1 usbserial 37173 3 ftdi_sio snd_hda_intel 32765 3 snd_hda_codec 109562 2 snd_hda_codec_realtek,snd_hda_intel snd_hwdep 13276 1 snd_hda_codec acer_wmi 23612 0 hid_logitech_dj 18177 0 snd_pcm 80845 2 snd_hda_intel,snd_hda_codec uvcvideo 67203 0 btusb 17912 2 snd_seq_midi 13132 0 videodev 86588 1 uvcvideo bluetooth 158438 23 rfcomm,bnep,btusb psmouse 72919 0 usbhid 41906 1 hid_logitech_dj snd_rawmidi 25424 1 snd_seq_midi intel_ips 17753 0 serio_raw 13027 0 hid 77367 2 hid_logitech_dj,usbhid ideapad_laptop 17890 0 sparse_keymap 13658 2 acer_wmi,ideapad_laptop lib80211_crypt_tkip 17275 0 snd_seq_midi_event 14475 1 snd_seq_midi snd_seq 51567 2 snd_seq_midi,snd_seq_midi_event wl 2646601 0 wmi 18744 1 acer_wmi i915 414672 3 drm_kms_helper 45466 1 i915 snd_timer 28931 2 snd_pcm,snd_seq mac_hid 13077 0 snd_seq_device 14172 3 snd_seq_midi,snd_rawmidi,snd_seq lib80211 14040 2 lib80211_crypt_tkip,wl drm 197692 4 i915,drm_kms_helper i2c_algo_bit 13199 1 i915 snd 62064 15 snd_hda_codec_realtek,snd_hda_intel,snd_hda_codec,snd_hwdep,snd_pcm,snd_rawmidi,snd_se q,snd_timer,snd_seq_device video 19068 1 i915 mei 36570 0 soundcore 14635 1 snd snd_page_alloc 14108 2 snd_hda_intel,snd_pcm lp 17455 0 parport 40930 3 parport_pc,ppdev,lp atl1c 36718 0 root@ghostrider:/etc/resolvconf# nm-tool NetworkManager Tool State: connected (global) - Device: eth1 [PoliTekno] ---------------------------------------------------- Type: 802.11 WiFi Driver: wl State: connected Default: yes HW Address: AC:81:12:7F:6B:B2 Capabilities: Speed: 54 Mb/s Wireless Properties WEP Encryption: yes WPA Encryption: yes WPA2 Encryption: yes Wireless Access Points (* = current AP) CnDStudios: Infra, 00:12:BF:3F:0A:8A, Freq 2412 MHz, Rate 54 Mb/s, Strength 85 WPA AIR_TIES: Infra, 00:1C:A8:6E:84:32, Freq 2462 MHz, Rate 54 Mb/s, Strength 72 WPA2 VKSS: Infra, 00:E0:4D:01:0D:47, Freq 2452 MHz, Rate 54 Mb/s, Strength 62 WPA2 PROGEDA: Infra, 00:1A:2A:60:BF:61, Freq 2462 MHz, Rate 54 Mb/s, Strength 47 WPA MobilAtolye: Infra, 72:2B:C1:65:75:3C, Freq 2422 MHz, Rate 54 Mb/s, Strength 35 WPA WPA2 AIRTIES_WAR-141: Infra, 00:1C:A8:AB:AA:48, Freq 2422 MHz, Rate 54 Mb/s, Strength 35 WPA WPA2 tilda_biri_yeni: Infra, 54:E6:FC:B0:3C:E9, Freq 2437 MHz, Rate 0 Mb/s, Strength 34 WEP *PoliTekno: Infra, 00:16:E3:40:C3:E4, Freq 2462 MHz, Rate 54 Mb/s, Strength 100 WPA2 AIRTIES_RJY: Infra, 00:1A:2A:BD:85:16, Freq 2462 MHz, Rate 54 Mb/s, Strength 55 WEP IPv4 Settings: Address: 0.0.0.0 Prefix: 24 (255.255.255.0) Gateway: 192.168.1.1 DNS: 192.168.1.1 - Device: eth0 ----------------------------------------------------------------- Type: Wired Driver: atl1c State: unavailable Default: no HW Address: F0:DE:F1:6C:90:65 Capabilities: Carrier Detect: yes Speed: 100 Mb/s Wired Properties Carrier: off root@ghostrider:/etc/resolvconf# sudo iwlist scan lo Interface doesn't support scanning. eth1 Scan completed : Cell 01 - Address: 00:16:E3:40:C3:E4 ESSID:"PoliTekno" Mode:Managed Frequency:2.462 GHz (Channel 11) Quality:5/5 Signal level:-48 dBm Noise level:-98 dBm IE: IEEE 802.11i/WPA2 Version 1 Group Cipher : CCMP Pairwise Ciphers (1) : CCMP Authentication Suites (1) : PSK Encryption key:on Bit Rates:1 Mb/s; 2 Mb/s; 5.5 Mb/s; 11 Mb/s; 18 Mb/s 24 Mb/s; 36 Mb/s; 54 Mb/s; 6 Mb/s; 9 Mb/s 12 Mb/s; 48 Mb/s Cell 02 - Address: 00:E0:4D:01:0D:47 ESSID:"VKSS" Mode:Managed Frequency:2.452 GHz (Channel 9) Quality:4/5 Signal level:-64 dBm Noise level:-98 dBm IE: IEEE 802.11i/WPA2 Version 1 Group Cipher : CCMP Pairwise Ciphers (1) : CCMP Authentication Suites (1) : PSK Encryption key:on Bit Rates:1 Mb/s; 2 Mb/s; 5.5 Mb/s; 11 Mb/s; 6 Mb/s 9 Mb/s; 12 Mb/s; 18 Mb/s; 24 Mb/s; 36 Mb/s 48 Mb/s; 54 Mb/s Cell 03 - Address: 00:1C:A8:AB:AA:48 ESSID:"AIRTIES_WAR-141" Mode:Managed Frequency:2.422 GHz (Channel 3) Quality:2/5 Signal level:-77 dBm Noise level:-95 dBm IE: IEEE 802.11i/WPA2 Version 1 Group Cipher : TKIP Pairwise Ciphers (2) : CCMP TKIP Authentication Suites (1) : PSK IE: Unknown: DDB20050F204104A0001101049001E007FC5100018DE7CF0D8B70223A62711C18926AC290E30303030303139631044000102103B0001031047001076B31BC241E953CB99C3872554425A28102100194169725469657320576972656C657373204E6574776F726B73102300074169723534343010240008312E322E302E31321042000F4154303939313131383030323832351054000800060050F20400011011000741697235343430100800020084103C000103 IE: WPA Version 1 Group Cipher : TKIP Pairwise Ciphers (2) : CCMP TKIP Authentication Suites (1) : PSK Encryption key:on Bit Rates:1 Mb/s; 2 Mb/s; 5.5 Mb/s; 11 Mb/s; 18 Mb/s 24 Mb/s; 36 Mb/s; 54 Mb/s; 6 Mb/s; 9 Mb/s 12 Mb/s; 48 Mb/s Cell 04 - Address: 72:2B:C1:65:75:3C ESSID:"MobilAtolye" Mode:Managed Frequency:2.422 GHz (Channel 3) Quality:2/5 Signal level:-78 dBm Noise level:-92 dBm IE: IEEE 802.11i/WPA2 Version 1 Group Cipher : TKIP Pairwise Ciphers (2) : TKIP CCMP Authentication Suites (1) : PSK IE: Unknown: DDA20050F204104A0001101044000102103B00010310470010BC329E001DD811B28601722BC165753C1021001D48756177656920546563686E6F6C6F6769657320436F2E2C204C74642E1023001C48756177656920576972656C6573732041636365737320506F696E74102400065254323836301042000831323334353637381054000800060050F204000110110009487561776569415053100800020084103C000100 IE: WPA Version 1 Group Cipher : TKIP Pairwise Ciphers (2) : TKIP CCMP Authentication Suites (1) : PSK Encryption key:on Bit Rates:1 Mb/s; 2 Mb/s; 5.5 Mb/s; 11 Mb/s; 9 Mb/s 18 Mb/s; 36 Mb/s; 54 Mb/s; 6 Mb/s; 12 Mb/s 24 Mb/s; 48 Mb/s Cell 05 - Address: 00:12:BF:3F:0A:8A ESSID:"CnDStudios" Mode:Managed Frequency:2.412 GHz (Channel 1) Quality:5/5 Signal level:-47 dBm Noise level:-95 dBm IE: WPA Version 1 Group Cipher : TKIP Pairwise Ciphers (1) : TKIP Authentication Suites (1) : PSK Encryption key:on Bit Rates:1 Mb/s; 2 Mb/s; 5.5 Mb/s; 11 Mb/s; 22 Mb/s 6 Mb/s; 9 Mb/s; 12 Mb/s; 18 Mb/s; 24 Mb/s 36 Mb/s; 48 Mb/s; 54 Mb/s Cell 06 - Address: 00:1C:A8:6E:84:32 ESSID:"AIR_TIES" Mode:Managed Frequency:2.462 GHz (Channel 11) Quality:5/5 Signal level:-56 dBm Noise level:-98 dBm IE: IEEE 802.11i/WPA2 Version 1 Group Cipher : CCMP Pairwise Ciphers (1) : CCMP Authentication Suites (1) : PSK Encryption key:on Bit Rates:1 Mb/s; 2 Mb/s; 5.5 Mb/s; 11 Mb/s; 22 Mb/s 6 Mb/s; 9 Mb/s; 12 Mb/s; 18 Mb/s; 24 Mb/s 36 Mb/s; 48 Mb/s; 54 Mb/s Cell 07 - Address: 54:E6:FC:B0:3C:E9 ESSID:"tilda_biri_yeni" Mode:Managed Frequency:2.437 GHz (Channel 6) Quality:1/5 Signal level:-85 dBm Noise level:-99 dBm Encryption key:on Bit Rates:1 Mb/s; 2 Mb/s; 5.5 Mb/s; 11 Mb/s; 6 Mb/s 12 Mb/s; 24 Mb/s; 36 Mb/s; 9 Mb/s; 18 Mb/s 48 Mb/s; 54 Mb/s Cell 08 - Address: 18:28:61:16:57:C3 ESSID:"obilet" Mode:Managed Frequency:2.437 GHz (Channel 6) Quality:1/5 Signal level:-88 dBm Noise level:-99 dBm IE: IEEE 802.11i/WPA2 Version 1 Group Cipher : TKIP Pairwise Ciphers (2) : CCMP TKIP Authentication Suites (1) : PSK IE: WPA Version 1 Group Cipher : TKIP Pairwise Ciphers (2) : CCMP TKIP Authentication Suites (1) : PSK Encryption key:on Bit Rates:1 Mb/s; 2 Mb/s; 5.5 Mb/s; 11 Mb/s; 18 Mb/s 24 Mb/s; 36 Mb/s; 54 Mb/s; 6 Mb/s; 9 Mb/s 12 Mb/s; 48 Mb/s Cell 09 - Address: 00:1A:2A:60:BF:61 ESSID:"PROGEDA" Mode:Managed Frequency:2.462 GHz (Channel 11) Quality:2/5 Signal level:-75 dBm Noise level:-98 dBm IE: WPA Version 1 Group Cipher : TKIP Pairwise Ciphers (1) : TKIP Authentication Suites (1) : PSK Encryption key:on Bit Rates:1 Mb/s; 2 Mb/s; 5.5 Mb/s; 11 Mb/s; 22 Mb/s 6 Mb/s; 9 Mb/s; 12 Mb/s; 18 Mb/s; 24 Mb/s 36 Mb/s; 48 Mb/s; 54 Mb/s eth0 Interface doesn't support scanning.

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• Tunneling in IPv6:

  - by JoesyXHN

  Hi, The concept of 6to4 tunneling is to do encapsulate and descapsulate an ipv6 packet through ipv4 network. The encapsulation process is: [IPv6 header][Transport Header][Application Protocol data] = encapsulation: [Ip4 Header][IPv6 header][Transport Header][Application Protocol data] I am talking from this infrastructure: Host A (IPv6) - Router R1 (dual stack) - Ipv4 net work - Router R2 (dual stack) - Host B (Ipv6) packet. The Ipv4 header in the encapsulation, which Ipv4 header is this among: Host A, Router R1, Router R2 and Host B? Thanks in advance.

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• What does it mean whether network device is Loopback?

  - by Gtker

  Does it mean that the Loopback device handles the request like ping localhost ? If so, there should be at least one device that's loopback,but seems none of my two network device is Loopback: rpcap://\Device\NPF_{45D5ADA0-095E-49F3-BEA1-E8754390F2D4} Description: Network adapter 'Intel(R) PRO/Wireless 2200BG Network Conne ction (Microsoft's Packet Scheduler) ' on local host Loopback: no rpcap://\Device\NPF_{783C5467-4026-473C-86A0-5E5A3708C624} Description: Network adapter 'Realtek RTL8169/8110 Family Gigabit Ethern et NIC (Microsoft's Packet Scheduler) ' on local host Loopback: no Can someone clarify all this?

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• Drag-to-disc CD or DVD writing software?

  - by Jeremy Rudd

  I just came to know about packet writing, which enables files to be written to disc one-by-one, instead of "burning" a whole disc all at once. After some initial searches all I've come up with is: Roxio Creator - includes DirectCD Nero Suite - includes InCD I'm looking for a functional CD/DVD packet writing software for Windows, without the extra bloat. Do you know of any?

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• when ping for two diffrent ip address one after other one of it always fails

  - by Mukesh

  when ping for two different ip address say 202.177.251.xxx and 59.183.5.yyy one after other one of it always fails. say if i ping one ip address it does not receive packet back and then i ping second one in a loop it receives the packet back though both are connected.

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• Problems with MGCP proxy creation

  - by Popof

  Hi, I'm trying to bypass my ISP router with my FreeBSD server (I've an optical connection so I've a RJ45 used to connect the box to WAN) Internet and TV are working fine (Using igmpproxy to forward TV stream) but I've a problem with phone. ISP's box is connected to the server which gives it a LAN address. The problem is that when the box builds MGCP packets (and especially SDP ones) it uses its LAN address. So I've think of writing an UDP proxy to handle MGCP and SDP packets in order to replace LAN address with server WAN address and then forward packet to WAN. Before starting coding I've captured stream packets using my server as a bridge between WAN connection and the ISP's box. And, in order to see if my solution is viable, I've tried to send those packets to the box using nemesis. I tried to send a packet (found in capture) containing an endpoint audit: AUEP 1447 aaln/[email protected] MGCP 1.0 F: A In the wireshark capture the box replied: 200 1447 OK A: a:PCMU;PCMA;G726-16;G726-24;G726-32;G726-40;G.723.1-5.3;G.723.1-6.3;G729;TELEPHONE-EVENT, fmtp:"TELEPHONE-EVENT 0-15,144,149,159", p:10-30, b:4-40, e:on, t:00, s:on, v:L;M;G;D, m:sendonly;recvonly;sendrecv;inactive;confrnce;replcate;netwtest;netwloop, dq-gi But when I use nemesis, I got an ICMP error: Port unreachable (Type 3, Code 3). To build this packet, WAN source address of the capture is replaced with my server LAN address, using the mgcp-callagent port (2727) and the packet is sent to the LAN address of the box at mgcp-gateway port (2427). The command I use is nemesis udp -S 192.168.2.1 -D 192.168.2.2 -x 2727 -y 2427 -P packet_to_send. I also tried an UDP scan to the box on callagent and gateway port: PORT STATE SERVICE 2727/udp open|filtered unknown 2427/udp closed unknown I found those results a little bit strange because it should be the 2427 port opened, as it was in capture. Internet Protocol, Src: <ISP MGCP Server>, Dst: <My WAN Address> User Datagram Protocol, Src Port: mgcp-callagent (2727), Dst Port: mgcp-gateway (2427) Does someone has any idea about how having my box responding to my requests ? Thanks in advance and sorry for my english.

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• Wake On LAN on request

  - by honzas

  Hi, I have a small home network with the router capable of running OpenWRT, is there some utility or firewall rule, which can be used to Wake On LAN on request. What I think - if I want to access my media centre (using for example SSH or HTTP) and it is suspended, is it possible to catch the ICMP packet (saying the machine is offline) and send the WOL packet to wakeup the machine and resend the SSH or HTTP request? Thanks

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• route http and ssh traffic normally, everything else via vpn tunnel

  - by Normadize

  I've read quite a bit and am close, I feel, and I'm pulling my hair out ... please help! I have an OpenVPN cliend whose server sets local routes and also changes the default gw (I know I can prevent that with --route-nopull). I'd like to have all outgoing http and ssh traffic via the local gw, and everything else via the vpn. Local IP is 192.168.1.6/24, gw 192.168.1.1. OpenVPN local IP is 10.102.1.6/32, gw 192.168.1.5 OpenVPN server is at {OPENVPN_SERVER_IP} Here's the route table after openvpn connection: # ip route show table main 0.0.0.0/1 via 10.102.1.5 dev tun0 default via 192.168.1.1 dev eth0 proto static 10.102.1.1 via 10.102.1.5 dev tun0 10.102.1.5 dev tun0 proto kernel scope link src 10.102.1.6 {OPENVPN_SERVER_IP} via 192.168.1.1 dev eth0 128.0.0.0/1 via 10.102.1.5 dev tun0 169.254.0.0/16 dev eth0 scope link metric 1000 192.168.1.0/24 dev eth0 proto kernel scope link src 192.168.1.6 metric 1 This makes all packets go via to the VPN tunnel except those destined for 192.168.1.0/24. Doing wget -qO- http://echoip.org shows the vpn server's address, as expected, the packets have 10.102.1.6 as source address (the vpn local ip), and are routed via tun0 ... as reported by tcpdump -i tun0 (tcpdump -i eth0 sees none of this traffic). What I tried was: create a 2nd routing table holding the 192.168.1.6/24 routing info (copied from the main table above) add an iptables -t mangle -I PREROUTING rule to mark packets destined for port 80 add an ip rule to match on the mangled packet and point it to the 2nd routing table add an ip rule for to 192.168.1.6 and from 192.168.1.6 to point to the 2nd routing table (though this is superfluous) changed the ipv4 filter validation to none in net.ipv4.conf.tun0.rp_filter=0 and net.ipv4.conf.eth0.rp_filter=0 I also tried an iptables mangle output rule, iptables nat prerouting rule. It still fails and I'm not sure what I'm missing: iptables mangle prerouting: packet still goes via vpn iptables mangle output: packet times out Is it not the case that to achieve what I want, then when doing wget http://echoip.org I should change the packet's source address to 192.168.1.6 before routing it off? But if I do that, the response from the http server would be routed back to 192.168.1.6 and wget would not see it as it is still bound to tun0 (the vpn interface)? Can a kind soul please help? What commands would you execute after the openvpn connects to achieve what I want? Looking forward to hair regrowth ...

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• What happens when ARP Request comes from a different subnet?

  - by gsinha

  What will happen when an ARP Request packet is sent from router1 to router2 in the following two cases? Will an ARP Reply be generated or the ARP Request packet be dropped? [router1]Intf1(20.0.0.1/24) ======== (40.0.0.1/24)Intf2[router2] [router1]Intf1(20.0.0.1/24) ======== (20.0.0.2/8) Intf2[router2] The topology above have a port "Intf1" on router "router1" connected a port "Intf2" on another router "router2" via a direct link(eg, a 1 Gbps cable).

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• Wake On LAN on request [closed]

  - by honzas

  Hi, I have a small home network with the router capable of running OpenWRT, is there some utility or firewall rule, which can be used to Wake On LAN on request. What I think - if I want to access my media centre (using for example SSH or HTTP) and it is suspended, is it possible to catch the ICMP packet (saying the machine is offline) and send the WOL packet to wakeup the machine and resend the SSH or HTTP request? Thanks

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• Postrouting rule in NAT table

  - by codingfreak

  Hi I have a strange question regarding NAT using iptables. When I do SNAT in a postrouting chain in NAT table at the end of the rule should I give -J ACCEPT? I see counters on the postrouting rule getting incremented but no packet leaving the machine. So does it mean the packet is DROPPED automatically?

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• other ways to change splash screen

  - by gcc

  I want change my splash screen .But when I download any splash screen packet in computer , I cannot install them .Every time ,computer gives me same warning "that packet is not a format wanted" -warning like this- I am asking "are there any other way to install splash screen?". note : I am also used 'Art manager' but it did not work properly.

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• EJB3 Business Delegates

  - by mykola

  Is there any reason for making delegate when using EJB3? Because the only real benefit i see from delegate is that it allows to hide lookup and access details of EJB architecture. Well it also provides some decoupling but it's mostly unused, imho. With EJB3 we have injection so now i can just create a variable with @EJB annotation and use it as is. Do i still need delegates? Is this injection resource consuming? I mean if i use it in JSF's request managed beans may be it's still better to use delegates just to lessen these injection calls? Thank you!

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• OpenPGP Signing

  - by singpolyma

  I'm reading RFC4880 in an attempt to produce an implementatdion of a subset of OpenPGP (RSA signatures) using http://phpseclib.sourceforge.net/. I have the publickey and compression-literal-signature packets parsed out. I can extract n and e and feed them to Crypt_RSA to construct a verifier. I tell it I'm using sha256. It then needs a "message" and a " signature" parametre. I get the signature data out of the signature packet no problem. The question I have is: what is "message"? According to sec tion 5.2.4 it's some combination of the literal data packet(s?) (their bodies or the whole packet?) and the "hashed" subpackets. Do I just concat all the data packets and the hashed packets together in the order they appear?

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• Does it make sense to have more than one UDP Datagram socket on standby? Are "simultaneous" packets

  - by Gubatron

  I'm coding a networking application on Android. I'm thinking of having a single UDP port and Datagram socket that receives all the datagrams that are sent to it and then have different processing queues for these messages. I'm doubting if I should have a second or third UDP socket on standby. Some messages will be very short (100bytes or so), but others will have to transfer files. My concern is, will the Android kernel drop the small messages if it's too busy handling the bigger ones? Update "The latter function calls sock_queue_rcv_skb() (in sock.h), which queues the UDP packet on the socket's receive buffer. If no more space is left on the buffer, the packet is discarded. Filtering also is performed by this function, which calls sk_filter() just like TCP did. Finally, data_ready() is called, and UDP packet reception is completed."

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• How come ftp protocol produces transmission errors sometimes if the data is using TCP, which is checksummed?

  - by Cray

  Every once in a while, downloading (especially large) files through ftp will produce errors. I am guessing that's also partly the reason why all major sites are publishing external checksums along with their downloads. How is this possible if ftp goes through TCP, which has checksum inbuilt and resends data if it is transmitted corruptly? One could argue that this is due to the short length of the CRC in the TCP protocol (which is 16bit I think, or something like that), and the collisions are simply happening too often. but 1) for this to be true, not only must there be a CRC collision, but also the random network error must modify both the CRC in the packet, and the packet itself so that the CRC will be valid for the new packet... Even with 16 bitCRC, is that so likely? 2) There are seemingly not many errors in, say, browsing the web which also goes through TCPIP.

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• What happens with TCP packets between two Socket.BeginReceive calls?

  - by Rodrigo

  I have a doubt about socket programming. I am developing a TCP packet sniffer. I am using Socket.BeginAccept, Socket.BeginReceive to capture every packet, but when a packet is received I have to process something. It is a fast operation, but would take some milliseconds, and then call BeginReceive again. My question is, what would happen if some packets are sent while I am processing, and haven't called BeginReceive? Are packets lost, or are they buffered internally? Is there a limit?

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