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  • problem with closing sockets

    - by Samantha
    Hi, I'm trying to write a client/server program with threads. I close the socket once the connexion is finished. The servers gets plenty of new connexions, and the socket number (file descriptor) increases very quickly: after 5 minutes running I was already at around file descriptor number 800! Is this a normal thing? Do threads share file descriptors? When I do close(sockfd); is the number released immediatly or after a some time? PS: I used to do with fork(), and I didn't have this issue. Thanks

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  • Implement a vpn

    - by jackson
    I want to build an application client(client.exe) - server to do the following: when the clients run it they are thrown in a VPN and they can communicate each other within 1 applicataion. For example : clients run client.exe and they can see each other in LAN ONLY in Starcraft. From what i have read the right type of vpn for this situation is Secured Socket Tunneling Protocol: "Secure socket tunneling protocol, also referred to as SSTP, is by definition an application-layer protocol. It is designed to employ a synchronous communication in a back and forth motion between two programs. It allows many application endpoints over one network connection, between peer nodes, thereby enabling efficient usage of the communication resources that are available to that network. " Question: I don't have experience with networking programming so my question for the ones who have, is this the right approach? PS1: i don't want something done like OpenVpn, i do this as learning exercise. PS2: the application is targeting Windows and i plan to use .NET Thanks for reading the whole story, i am waiting for your replies.

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  • Need help in understanding the mapping of user-space send, sendto, sendmsg to kernel-space sendmsg

    - by bala1486
    Hello, I am trying to implement my own transport layer protocol in Linux for an experiment. I am going to use socket interface and add my protocol using sock_register. For the proto_ops i can see that the parameters for the sendmsg and recvmsg are (struct kiocb *iocb, struct socket *sock, struct msghdr *msg, size_t len, int flags). But there are three types of user api's send, sendto, sendmsg. Of these three only sendmsg contains a parameter for msghdr. I find that the other two api's are incompatible with the parameters supplied by the kernel to my kernel-space sendmsg function. So what happens when we use send and sendto user-space api's? Hope i am clear.. Thanks, Bala

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  • Is it ok to Swallow SocketExceptions in some situations? (C#)

    - by NoPyGod
    Let's say I've programmed an application which connects to a server using the Socket Class (TCP). If I encounter a SocketException while reading or writing, then obviously I have to do go ahead and run a disconnection routine to change the application's state to Disconnected. But what if I've started to Disconnect, and while I'm cleaning up, a SocketException occurs? The SocketException doesn't really mean anything to me, as I was going to shutdown the socket myself anyway.. so is it ok to swallow it? I really want to know what the best practice for this situation is.

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  • How to implement file transfer with Java sockets?

    - by ZeKoU
    Hello, I am working on a chat implementation with Java sockets. I have focused on few functionalities, like authentication, one person chat and a group chat. I was thinking about adding file transfer functionality, and I wonder what's the good practice about this. Should I have separate socket on the server with different port listening just for file transfers? Right now input and output streams that I get from server socket are binded to Scanner and PrintWriter objects respectively, so I find it hard to use that for file transfer. Any patterns you guys could recommend or give me good recommendations are very appreciated. Thanks, ZeKoU

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  • Swing code in sockets

    - by asb
    I am learning swings for making GUI. I was thinking which is the best possible way in case of socket with swings. 1. The whole swing code goes in the server file. All the handlers and logic in on server side. Client only create socket. 2. The server have logic part. The code for the swing to display interface goes on client side. Client Creates stream to send / rec. data from server. Whch is the good way out of 2 ?

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  • Socket in C: recv overwrite a char[]

    - by Possa
    Hi all, I'm trying to make a little client-server script like many others that I've done in the past. But in this one I have a problem. It is better if I post the code and the output it give me. Code: #include <mysql.h> //not important now #include <stdlib.h> #include <sys/types.h> #include <sys/socket.h> #include <netinet/in.h> #include <arpa/inet.h> #include <netdb.h> #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <signal.h> #include <string.h> //constant definition #define SERVER_PORT 2121 #define LINESIZE 21 //global var definition char victim_ip[LINESIZE], file_write[LINESIZE], hacker_ip[LINESIZE]; //function void leggi (int); //not use now for debugging purpose //void scriviDB (); //not important now main () { int sock, client_len, fd; struct sockaddr_in server, client; // transport end point if((sock = socket(AF_INET, SOCK_STREAM, 0)) == -1) { perror("system call socket fail"); exit(1); } server.sin_family = AF_INET; server.sin_addr.s_addr = inet_addr("10.10.10.1"); server.sin_port = htons(SERVER_PORT); // binding address at transport end point if (bind(sock, (struct sockaddr *)&server, sizeof server) == -1) { perror("system call bind fail"); exit(1); } //fprintf(stderr, "Server open: listening.\n"); listen(sock, 5); /* managae client connection */ while (1) { client_len = sizeof(client); if ((fd = accept(sock, (struct sockaddr *)&client, &client_len)) < 0) { perror("accepting connection"); exit(1); } strcpy(hacker_ip, inet_ntoa(client.sin_addr)); printf("1 %s\n", hacker_ip); //debugging purpose //leggi(fd); ////////////////////////// //receive client recv(fd, victim_ip, LINESIZE, 0); victim_ip[sizeof(victim_ip)] = '\0'; printf("2 %s\n", hacker_ip); //debugging purpose recv(fd, file_write, LINESIZE, 0); file_write[sizeof(file_write)] = '\0'; printf("3 %s\n", hacker_ip); //debugging purpose printf("%s@%s for %s\n", file_write, victim_ip, hacker_ip); //send to client send(fd, hacker_ip, 40, 0); //now is hacker_ip for debug ///////////////////////// close(fd); }//end while exit(0); } //end main Client send string: ./send -i 10.10.10.4 -f filename.ext so the script send -i (IP) and -f (FILE) at the server. Here's my output server side: 1 10.10.10.6 2 10.10.10.6 3 [email protected] for As you can see the printf(3) and the printf(ip,file,ip) fail. I don't know how and where but someone overwrite my hacker_ip string. Thanks for your help! :)

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  • What do I need to distribute (keys, certs) for Python w/ SSL-socket connection?

    - by fandingo
    I'm trying to write a generic server-client application that will be able to exchange data amongst servers. I've read over quite a few OpenSSL documents, and I have successfully setup my own CA and created a cert (and private key) for testing purposes. I'm stuck with Python 2.3, so I can't use the standard "ssl" library. Instead, I'm stuck with PyOpenSSL, which doesn't seem bad, but there aren't many documents out there about it. My question isn't really about getting it working. I'm more confused about the certificates and where they need to go. Here are my two programs that do work: Server: #!/bin/env python from OpenSSL import SSL import socket import pickle def verify_cb(conn, cert, errnum, depth, ok): print('Got cert: %s' % cert.get_subject()) return ok ctx = SSL.Context(SSL.TLSv1_METHOD) ctx.set_verify(SSL.VERIFY_PEER|SSL.VERIFY_FAIL_IF_NO_PEER_CERT, verify_cb) # ?????? ctx.use_privatekey_file('./Dmgr-key.pem') ctx.use_certificate_file('Dmgr-cert.pem') # ?????? ctx.load_verify_locations('./CAcert.pem') server = SSL.Connection(ctx, socket.socket(socket.AF_INET, socket.SOCK_STREAM)) server.bind(('', 50000)) server.listen(3) a, b = server.accept() c = a.recv(1024) print(c) Client: from OpenSSL import SSL import socket import pickle def verify_cb(conn, cert, errnum, depth, ok): print('Got cert: %s' % cert.get_subject()) return ok ctx = SSL.Context(SSL.TLSv1_METHOD) ctx.set_verify(SSL.VERIFY_PEER, verify_cb) # ?????????? ctx.use_privatekey_file('/home/justin/code/work/CA/private/Dmgr-key.pem') ctx.use_certificate_file('/home/justin/code/work/CA/Dmgr-cert.pem') # ????????? ctx.load_verify_locations('/home/justin/code/work/CA/CAcert.pem') sock = SSL.Connection(ctx, socket.socket(socket.AF_INET, socket.SOCK_STREAM)) sock.connect(('10.0.0.3', 50000)) a = Tester(2, 2) b = pickle.dumps(a) sock.send("Hello, world") sock.flush() sock.send(b) sock.shutdown() sock.close() I found this information from ftp://ftp.pbone.net/mirror/ftp.pld-linux.org/dists/2.0/PLD/i586/PLD/RPMS/python-pyOpenSSL-examples-0.6-2.i586.rpm which contains some example scripts. As you might gather, I don't fully understand the sections between the " # ????????." I don't get why the certificate and private key are needed on both the client and server. I'm not sure where each should go, but shouldn't I only need to distribute one part of the key (probably the public part)? It undermines the purpose of having asymmetric keys if you still need both on each server, right? I tried alternating removing either the pkey or cert on either box, and I get the following error no matter which I remove: OpenSSL.SSL.Error: [('SSL routines', 'SSL3_READ_BYTES', 'sslv3 alert handshake failure'), ('SSL routines', 'SSL3_WRITE_BYTES', 'ssl handshake failure')] Could someone explain if this is the expected behavior for SSL. Do I really need to distribute the private key and public cert to all my clients? I'm trying to avoid any huge security problems, and leaking private keys would tend to be a big one... Thanks for the help!

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  • Using Audio Queue Services to play PCM data over a socket connection

    - by Rohan
    I'm writing a remote desktop client for the iPhone and I'm trying to implement audio redirection. The client is connected to the server over a socket connection, and the server sends 32K chunks of PCM data at a time. I'm trying to use AQS to play the data and it plays the first two seconds (1 buffer worth). However, since the next chunk of data hasn't come in over the socket yet, the next AudioQueueBuffer is empty. When the data comes in, I fill the next available buffer with the data and enqueue it with AudioQueueEnqueueBuffer. However, it never plays these buffers. Does the queue stop playing if there are no buffers in the queue, even if you later add a buffer? Here's the relevant part of the code: void wave_out_write(STREAM s, uint16 tick, uint8 index) { if(items_in_queue == NUM_BUFFERS){ return; } if(!playState.busy){ OSStatus status; status = AudioQueueNewOutput(&playState.dataFormat, AudioOutputCallback, &playState, CFRunLoopGetCurrent(), NULL, 0, &playState.queue); if(status == 0){ for(int i=0; i<NUM_BUFFERS; i++){ AudioQueueAllocateBuffer(playState.queue, 40000, &playState.buffers[i]); } AudioQueueAddPropertyListener(playState.queue, kAudioQueueProperty_IsRunning, MyAudioQueuePropertyListenerProc, &playState); status = AudioQueueStart(playState.queue, NULL); if(status ==0){ playState.busy = True; } else{ return; } } else{ return; } } playState.buffers[queue_hi]->mAudioDataByteSize = s->size; memcpy(playState.buffers[queue_hi]->mAudioData, s->data, s->size); AudioQueueEnqueueBuffer(playState.queue, playState.buffers[queue_hi], 0, 0); queue_hi++; queue_hi = queue_hi % NUM_BUFFERS; items_in_queue++; } void AudioOutputCallback(void* inUserData, AudioQueueRef outAQ, AudioQueueBufferRef outBuffer) { PlayState *playState = (PlayState *)inUserData; items_in_queue--; } Thanks!

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  • socket problem with MySQL

    - by Hristo
    This is a recent problem... MySQL was working and a couple of days ago I must have done something. I deleted MySQL and tried reinstalling using the .dmg file. The mysql.sock file never gets created and I get the following error messages: Hristo$ mysql Enter password: ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/mysql/mysql.sock' (2) I also tried stopping Apache and installing but Apache gave me an error... I don't know if this is good or bad: Hristo$ sudo apachectl stop launchctl: Error unloading: org.apache.httpd I tried the MacPorts installation as well but the socket file still didn't get created. I don't really know what to do and I don't want to reinstall Snow Leopard and start from scratch :/ I also tried installing the 32-bit version and same deal. No luck. Finally... I tried doing the source installation but when I get to the configuration step, I get the following error: -bash: ./configure: No such file or directory The file is "mysql-5.1.47-osx10.6-x86_64.tar.gz" so I think it is the proper file for source installation and yes I have a 64 bit system. I don't know what to do anymore. Any ideas? Thanks, Hristo

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  • Can't connect to local MySQL server through socket

    - by Martin
    I was trying to tune the performance of a running mysql-server by running this command: mysqld_safe --key_buffer_size=64M --table_cache=256 --sort_buffer_size=4M --read_buffer_size=1M & After this i'm unable to connect mysql from the server where mysql is running. I get this error: ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (111) However, luckily i can still connect to mysql remotely. So all my webservers still have access to mysql and are running without any problems. Because of this though i don't want to try to restart the mysql server since that will probably fuck everything up. Now i know that mysqld_safe is starting the mysql-server, and since the mysql server was already running i guess it's some kind of problem with two mysql servers running and listening to the same port. Is there some way to solve this problem without restarting the initial mysql server? UPDATE: This is what ps xa | grep "mysql" says: 11672 ? S 0:00 /bin/sh /usr/bin/mysqld_safe 11780 ? Sl 175:04 /usr/sbin/mysqld --basedir=/usr --datadir=/var/lib/mysql --user=mysql --pid-file=/var/run/mysqld/mysqld.pid --socket=/var/run/mysqld/mysqld.sock --port=3306 11781 ? S 0:00 logger -t mysqld -p daemon.error 12432 pts/0 R+ 0:00 grep mysql

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  • IOCP multiple socket completionports in same container

    - by Ohmages
    For the past couple of days I have been thinking about how to solve one of my problems I am facing, and I have tried to research the topic but don't really know what I can do. I have 2 sockets in the same struct that both have the same completionport. Problem is, they both use different protocols. Is there a way that I can find out which socket got triggered? Their called game_socket, and client_socket Example code would be something like... while (true) { error = GetQueuedCompletionStatus(CompletionPort, &BytesTransfered, (PULONG_PTR)&Key, &lpOverlapped, 0); srvc = CONTAINING_RECORD ( lpOverlapped, client , ol ); if ( error == TRUE ) { cout << endl << "SOCKET: [" << srvc->client_socket << "] TRIGGERED - WORKER THREAD" << endl; cout << endl << "BytesTransfered: [" << BytesTransfered << "]" << endl; if ( srvc->game_client triggered ) { // .. this code } else { // .. this code } Any ideas our help would be appreciated :)

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  • Socket.Recieve Failing When Multithreaded

    - by Qua
    The following piece of code runs fine when parallelized to 4-5 threads, but starts to fail as the number of threads increase somewhere beyond 10 concurrentthreads int totalRecieved = 0; int recieved; StringBuilder contentSB = new StringBuilder(4000); while ((recieved = socket.Receive(buffer, SocketFlags.None)) > 0) { contentSB.Append(Encoding.ASCII.GetString(buffer, 0, recieved)); totalRecieved += recieved; } The Recieve method returns with zero bytes read, and if I continue calling the recieve method then I eventually get a 'An established connection was aborted by the software in your host machine'-exception. So I'm assuming that the host actually sent data and then closed the connection, but for some reason I never recieved it. I'm curious as to why this problem arises when there are a lot of threads. I'm thinking it must have something to do with the fact that each thread doesn't get as much execution time and therefore there are some idle time for the threads which causes this error. Just can't figure out why idle time would cause the socket not to recieve any data.

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  • Java Socks Proxy Socket Error

    - by Ionut Ungureanu
    I am trying to create a http request through a SOCKS (v4 / v5) proxy in Java. After reading about socks communication protocol on WikiPedia, I have put togheter this piece of code: Socket sock = new Socket(); InetSocketAddress remoteProxyAddress = new InetSocketAddress(proxy ip, proxy port); sock.connect(remoteProxyAddress, connTimeout); InputStream in = sock.getInputStream(); OutputStream out = sock.getOutputStream(); out.write(0x04); out.write(0x01); out.write((endpoint.getPort() >> 8) & 0xff); out.write((endpoint.getPort() >> 0) & 0xff); out.write(endpoint.getAddress().getAddress()); out.write(0x0); out.flush(); And here comes the part where I read from the proxy server. The problem is that the response is always "-1". I have tried the proxy on Firefox and it works perfect. So... the problem is in my app. Can anyone help me? Thanks!

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  • C#: socket closing if user user exists

    - by corvallo
    Hi to everyone I'm trying to create a server/client application for a school project. This is the scenario: a server on a given port, multiple user connected, each user has it's own username. Now I want to check if a user that try to connect to the user use a valid username, for example if a user with username A it's already connected a new user that want to connect cannot use the username A. If this happen the server answer to the new client with an error code. This is the code for this part private void Receive() { while (true) { byte[] buffer = new byte[64]; socket.Receive(buffer); string received = Encoding.Default.GetString(buffer); if (received.IndexOf("!error") != -1) { string[] mySplit = received.Split(':'); string errorCode = mySplit[1].Trim((char)0); if (errorCode == "user exists") { richTextBox1.AppendText("Your connection was refused by server, because there's already another user connected with the username you choose"); socket.Disconnect(true); connectBtn.Enabled = true; } } } } But when I try to do this the program crash and visual studio said that there's an invalid cross-thread operation on richTextBox1. Any ideas. Thank you in advance.

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  • How to detect a Socket disconnection?

    - by AngryHacker
    I've implemented a task using the async Sockets pattern in Silverlight 3. I started with Michael Schwarz's implementation and built on top of that. So basically, my Silverlight app establishes a persistent socket connection to a device and then data flows both ways as necessary between the device and the Silverlight app. One thing I am struggling with is how to detect disconnection. I could think of 2 approaches: Keep-Alive. I know this can be done at the Sockets level, but I am not sure how to do this in an async model. How would the Socket class let me know there has been a disconnection. Manual keep alive. Basically, I am having the Silverlight app send a dummy packet every 20 seconds or so. If it fails, I'd assume disconnection. However, incredibly, SocketAsyncEventArgs.SocketError always reports success, even if I simply unplug the device that the Silverlight app is connected to. I am not sure whether this is a bug or what or perhaps I need to upgrade to SL4. Any ideas, direction or implementation would be appreciated.

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  • Flash browser game - HTTP + PHP vs Socket + Something else

    - by Maurycy Zarzycki
    I am developing a non-real time browser RPG game (think Kingdom of Loathing) which would be played from within a Flash app. At first I just wanted to make the communication with server using simply URLLoader to tell PHP what I am doing, and using $_SESSION to store data needed in-between request. I wonder if it wouldn't be better to base it on a socket connection, an app residing on a server written in Java or Python. The problem is I have never ever written such an app so I have no idea how much I'd have to "shift" my thoughts from simple responding do request (like PHP) to continuously working application. I won't hide I am also concerned about the memory and CPU usage of such Server app, when for example there would be hundreds of users connected. I've done some research. I have tried to do some research, but thanks to my nil knowledge on the sockets subject I haven't found anything helpful. So, considering the fact I don't need real time data exchange, will it be wise to develop the server side part as socket server, not in plain ol' PHP?

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  • ERROR 2002 (HY000): Can’t connect to local MySQL server through socket ‘/tmp/mysql.sock’ (2)

    - by Imran
    Can someone please help as i've spent all day trying to fix this. I installed the latest XAMPP and now i can't connect to mysql from terminal.I checked my .profile file and the PATH seems ok. Does anyone know whats happened and what's the solution? PATH=$PATH:/Applications/XAMPP/xamppfiles/bin export PATH THIS IS A PROGRAMMING QUESTION AS I'M A PHP DEVELOPER TRYING TO DO MY JOB! Thankyou soo much in advance;-)

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  • opening socket to google hangs on SYN_SENT

    - by puchu
    I have 2 computers now: downloader (asus at4nm10t-i) with debian and desktop (asus sabertooth 990fx) with gentoo in the same network under NAT even with the same ethernet card: RTL8111E. driver r8169 is compiled as module on both computers. Sometimes in evenings desktop cannot connect to google and all its services like now: curl -v http://www.google.by on downloader it received server's answer immediately. on desktop it hanged and when I ran in other terminal: netstat -ntp | grep curl >>tcp 0 1 192.168.0.7:54126 173.194.35.191:80 SYN_SENT 4876/curl after 1-2 minutes it received server's answer. I was tried to change ip of network, mac address of desktop but nothing changed. When I was trying to connect to another services except google: curl -v http://www.yahoo.com both computers received answers immediately! Only when I rebooted desktop it begins to work with google services correctly I cant understand what is this bug related to. In which bugtracker should I post this: r8169 or linux kernel or google? PS. Desktop was checked with memtest: 5 passes - no errors

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  • Socket 1155 vs 2011 vs Haswell

    - by woody
    The title says it all. I am trying to decide between sockets and just cant pinpoint which to get based on pros and cons. The build this will go into will be my primary PC. It will be used for every day computing, coding, some multimedia and gaming. I have read that 1155 and 2011 will be dead within the new year and that Haswell will double the performance of Ivy Bridge. What is a general run down on the different sockets? Pros and Cons? More specifically what are the technical differences between the three?

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  • Socket error sendig data from loftware to zebra zm400

    - by Mike
    I have a problem with my Zebra zm 400. I print a label from loftware, and in random times comes the label not out from the printer. When this issue comes, then I can't ping my printer or I can't achive the webpage of the printer. Only I need to disconnect the UTP cable from te Zebra. and after this disconnect work the printer fine. And in variale intervals come this problem again! Thanks and regards, Mike

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  • "Address already in use" error from socket bind, when ports are not being used

    - by Ivan Novick
    I can not bind (using C or python sockets) to any port in the range: 59969-60000 Using lsof, netstat and fuser I do not see any processes using these ports. Other ports such as 59900-59968 and 60001-60009 I can bind to them. My OS: is CentOS release 5.5 (Final) 2.6.18-194.3.1.el5 There must be something missing? Anyone have any idea how to debug why this port range is not usable? Cheers, Ivan

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  • Apache2 process stuck at 100% cpu, CLOSE_WAIT socket lingering

    - by mmazing
    I've troubleshooted the heck out of this today, and I can't seem to find any information on how to determine what is happening exactly. Basically, on my development server, another developer is causing CLOSE_WAIT connections that eat up one or more apache2 processes for several hours if I don't restart apache2. strace on any of the processes yields no information, only that it was able to attach. mod_proxy is not enabled. KeepAlive is on, KeepAliveTimeout is 15 seconds, MaxKeepAliveRequests is 100. From what I've been reading, this may or may not be an apache issue at all, just that that's how CLOSE_WAIT works (the server is waiting for a FIN packet to close the connection). I just can't believe that a server would be crippled so easily by not receiving a packet from a remote host telling it to close the connection. Especially without any intervention for well over an hour. Any tips? I'm about to pull my hair out. Edit : Also, there are no unusual entries in any apache log files. Edit 2: lsof -i shows only a single CLOSE_WAIT per hanging process. (That's what has been bothering me about this, as most other discussions talk about many CLOSE_WAIT connections, while I only have one per process.) The nature of the code that is running (php) doesn't really lend itself to closing open connections and whatnot. I can run the same code that he is executing with the same session data, and not result in a hanging process.

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  • Determine $DISPLAY socket name on OS X 10.6?

    - by Nate
    I'm looking to do something that's a little odd. I'm SSH'ing from a server to a Snow Leopard client to start an X11 data display process. In other words, SSH's X11 forwarding isn't what I want. I can do: client$ echo $DISPLAY /tmp/launch-SOMETHING/org.x:0 client$ ls -l $DISPLAY srwx------ 1 myuser wheel 0 Dec 9 15:47 /tmp/launch-SOMETHING/org.x:0 And, when I do: server$ ssh myuser@client client$ export DISPLAY=/tmp/launch-SOMETHING/org.x:0 client$ xterm I happily get my xterm. What I need, then, is some way to find out the correct value for $DISPLAY in my ssh session. From what I've read, $DISPLAY is set by launchd, but I haven't found any way to see that value. If it matters, I know that when my process connects from $server to $client, $client will logged in to the terminal as the same user.

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