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  • IP Tables won't save the rule.

    - by ArchUser
    Hello, I'm using ArchLinux and I have an IP tables rule that I know works (from my other server), and it's in /etc/iptables/iptables.rules, it's the only rule set in that directory. I run, /etc/rc.d/iptables save, then /etc/rc.d/iptables/restart, but when I do "iptables --list", I get ACCEPTs on INPUT,FORWARD & OUTPUT. # Generated by iptables-save v1.4.8 on Sat Jan 8 18:42:50 2011 *filter :INPUT DROP [0:0] :FORWARD DROP [0:0] :OUTPUT ACCEPT [216:14865] :BRUTEGUARD - [0:0] :interfaces - [0:0] :open - [0:0] -A INPUT -p icmp -m icmp --icmp-type 18 -j DROP -A INPUT -p icmp -m icmp --icmp-type 17 -j DROP -A INPUT -p icmp -m icmp --icmp-type 10 -j DROP -A INPUT -p icmp -m icmp --icmp-type 9 -j DROP -A INPUT -p icmp -m icmp --icmp-type 5 -j DROP -A INPUT -p icmp -j ACCEPT -A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT -A INPUT -j interfaces -A INPUT -j open -A INPUT -p tcp -j REJECT --reject-with tcp-reset -A INPUT -p udp -j REJECT --reject-with icmp-port-unreachable -A INPUT -p tcp -m tcp ! --tcp-flags FIN,SYN,RST,ACK SYN -m state --state NEW -j DROP -A INPUT -f -j DROP -A INPUT -p tcp -m tcp --tcp-flags FIN,SYN,RST,PSH,ACK,URG FIN,SYN,RST,PSH,ACK,URG -j DROP -A INPUT -p tcp -m tcp --tcp-flags FIN,SYN,RST,PSH,ACK,URG NONE -j DROP -A INPUT -i eth+ -p icmp -m icmp --icmp-type 8 -j DROP -A BRUTEGUARD -m recent --set --name BF --rsource -A BRUTEGUARD -m recent --update --seconds 600 --hitcount 20 --name BF --rsource -j LOG --log-prefix "[BRUTEFORCE ATTEMPT] " --log-level 6 -A BRUTEGUARD -m recent --update --seconds 600 --hitcount 20 --name BF --rsource -j DROP -A interfaces -i lo -j ACCEPT -A open -p tcp -m tcp --dport 80 -j ACCEPT -A open -p tcp -m tcp --dport 10011 -j ACCEPT -A open -p udp -m udp --dport 9987 -j ACCEPT -A open -p tcp -m tcp --dport 30033 -j ACCEPT -A open -p tcp -m tcp --dport 8000 -j ACCEPT -A open -p tcp -m tcp --dport 8001 -j ACCEPT -A open -s 76.119.125.61 -p tcp -m tcp --dport 21 -j ACCEPT -A open -s 76.119.125.61 -p tcp -m tcp --dport 3306 -j ACCEPT -A open -p tcp -m tcp --dport 22 -j BRUTEGUARD -A open -s 76.119.125.61 -p tcp -m tcp --dport 22 -m state --state NEW,RELATED,ESTABLISHED -j ACCEPT COMMIT # Completed on Sat Jan 8 18:42:50 2011

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  • Lose internet connection, yet online games continue

    - by Mike
    For the past week or so, my internet connection has been anything but stable. Restarting my modem/router always fixes the problems, but since it has occurred so often, I'm noticing confusing patterns which I was hoping someone could help answer. My internet connection kicks out about 4-5 times a day. The sure-fire way to fix it is to restart my all-in-one modem/router. Sometimes I can diagnose the problem on my laptop which resets my wireless network adapter and fixes the problem, but not always. If that doesn't fix the problem, it usually reports that the connection between the modem and internet is the problem which requires a restart of the router. The odd thing which baffles me is that my connection is supposedly lost such that no browsers can connect to sites, yet things like online games still continue to play without issue. How is this possible? I thought maybe the game was running locally on my PC but that couldn't be the answer because I was still getting messages from other players. So my real question is: How can my internet browsers (firefox, chrome, even IE) lose connection to the internet, but other applications like online games not? Am I actually losing connection or am I mistaken? Edit: I'd also like to add that netflix on my PS3 which is directly connected to the same access point will also lose connection. So internet browsers and netflix lose their internet connection while online games continue without an issue.

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  • Data Connection Library in SharePoint Server 2010

    - by Wayne
    What is a Data Connection Library in SharePoint Server 2010? A Data Connection Library in Microsoft SharePoint Server 2010 is a library that can contain two kinds of data connections: an Office Data Connection (ODC) file or a Universal Data Connection (UDC) file. Microsoft InfoPath 2010 uses data connections that comply with the Universal Data Connection (UDC) file schema and typically have either a *.udcx or *.xml file name extension. Data sources described by these data connections are stored on the server and can be used in standard form templates and browser-enabled form templates. How to create a SharePoint Server Data Connection Library? 1. Browse to a SharePoint Server 2010 site on which you have at least Design permissions. If you are on the root site, create a new site before you continue with the next step. 2. On the Site Actions menu, click More Options. 3. On the Create page, click Library under Filter By, and then click Data Connection Library. 4. On the right side of the Create page, type a name for the library, and then click the Create button. 5. Copy the URL of the new data connection library. How to create a new data connection file in InfoPath? 1. Open InfoPath Designer 2010, click Blank Form, and then click Design Form. 2. On the Data tab, click Data Connections, and then click Add. 3. In the Data Connection Wizard, click Create a new connection to, click Receive data, and then click Next. 4. Click the kind of data source that you are connecting to, such as Database, Web service, or SharePoint library or list, and then click Next. 5. Complete the remaining steps in the Data Connection Wizard to configure your data connection, and then click Finish to return to the Data Connections dialog box. 6. In the Data Connections dialog box, click Convert to Connection File. 7. In the Convert Data Connection dialog box, enter the URL of the data connection library that you previously copied (delete "Forms/AllItems.aspx" and anything following it from the URL), enter a name for the data connection file at the end of the URL, and then click OK. It will take a few moments to convert and save the data connection file to the library. 8. Confirm that the data connection was converted successfully by examining the Details section of the Data Connections dialog box while the name of the converted data connection is selected. 9. Browse to the SharePoint data connection library, click the drop-down next to the name of the data connection, click Approve/Reject, click Approved, and then click OK. Take advantage of SharePoint Data Connection Library and other useful features of SharePoint family of products that include, SharePoint Foundation 2010, MOSS 2007 and free SharePoint templates or web parts.

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  • tcp flags in iptables: What's the difference between RST SYN and RST and SYN RST ? When to use ALL?

    - by Kris
    I'm working on a firewall for a virtual dedicated server and one of the things I'm looking into is port scanners. TCP flags are used for protection. I have 2 questions. The rule: -p tcp --tcp-flags SYN,ACK,FIN,RST SYN -j DROP First argument says check packets with flag SYN Second argument says make sure the flags ACK,FIN,RST SYN are set And when that's the case (there's a match), drop the tcp packet First question: I understand the meaning of RST and RST/ACK but in the second argument RST SYN is being used. What's the difference between RST SYN and RST and SYN RST ? Is there a "SYN RST" flag in a 3 way handshake ? Second question is about the difference between -p tcp --tcp-flags SYN,ACK,FIN,RST SYN -j DROP and -p tcp --tcp-flags ALL SYN,ACK,FIN,RST SYN -j DROP When should ALL be used ? When I use ALL, does that mean if the tcp packet with the syn flag doesn't have the ACK "and" the FIN "and" the RST SYN flags set, there will be no match ?

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  • Single TCP-CLOSE_WAIT connection brings down application till restart

    - by broun
    Recently found a behaviour where my application had a connection in TCP Close_wait state till the app was restarted (after about 5 hours). But during this period the SUnreclaim space was also increasing constantly and went down on restart. The application is runnning on a rhel5 os and Im not very familiar with the memory management system. Would appreciate if someone clould tell me what extactly is the Ureclaim space and why it is increasing in sync with the close_wait.

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  • SUnreclaim size increasing in syc with a TCP-CLOSE_WAIT till application restart

    - by maver1k
    Recently found a behaviour where my application had a connection in TCP Close_wait state till the app was restarted (after about 5 hours). But during this period the SUnreclaim space was also increasing constantly and went down on restart. The application is runnning on a rhel5 os and Im not very familiar with the memory management system. Would appreciate if someone clould tell me what extactly is the Ureclaim space and why it is increasing in sync with the close_wait. Thanks.

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  • triple duplicate acknowledgement in TCP congestion control

    - by Salvador Dali
    If this doesn't belong here, please tell me where is an appropriate place for such question. I am trying to understand ideas behind tcp congestion control mechanisms, and I am failing to understand why we need triple duplicate acknowledgement to trigger window change. In my opinion, double duplicate acknowledgement will be enough to get that the previous package is lost. So why we need the third ack?

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  • Alternate Out of Order TCP Packets problem

    - by Sunil
    I am having a network of windows and embedded nodes connected on a series of cisco switch. I have been seeing some serious network problems from few days. Used wireshark to capture the network trace and see every alternate tcp packets being marked as "out of order". Any pointers on how to troubleshoot this problem?

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  • Detect TCP connection close when playing Flash video

    - by JoJo
    On the Flash client side, how do I detect when the server purposely closes the TCP connection to its video stream? I'll need to take action when this occurs - maybe attempt to restart the video or display an error message. Currently, the connection closing and the connection being slow look the same to me. The NetStream object ushers a NetStream.Play.Stop event in both cases. When the connection is slow, it usually recovers by itself within seconds. I wish to only take action when the connection is closed, not when it is slow. Here's how my general setup looks like. It's the basic NetConnection-NetStream-Video setup. this.vidConnection = new NetConnection(); this.vidConnection.addEventListener(AsyncErrorEvent.ASYNC_ERROR, this.connectionAsyncError); this.vidConnection.addEventListener(IOErrorEvent.IO_ERROR, this.connectionIoError); this.vidConnection.addEventListener(NetStatusEvent.NET_STATUS, this.connectionNetStatus); this.vidConnection.connect(null); this.vidStream = new NetStream(this.vidConnection); this.vidStream.addEventListener(AsyncErrorEvent.ASYNC_ERROR, this.streamAsyncError); this.vidStream.addEventListener(IOErrorEvent.IO_ERROR, this.streamIoError); this.vidStream.addEventListener(NetStatusEvent.NET_STATUS, this.streamNetStatus); this.vid.attachNetStream(this.vidStream); None of the error events fire when the server closes the TCP or when the connection freezes up. Only the NetStream.Play.Stop event fires. Here's a trace of what happens from initially playing the video to the TCP connection closing. connection net status = NetConnection.Connect.Success playStream(http://192.168.0.44/flv/4d29104a9aefa) NetStream.Play.Start NetStream.Buffer.Flush NetStream.Buffer.Full NetStream.Buffer.Empty checkDimensions 0 0 onMetaData NetStream.Buffer.Full NetStream.Buffer.Flush checkDimensions 960 544 NetStream.Buffer.Empty NetStream.Buffer.Flush NetStream.Play.Stop

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  • Can't seem to get C TCP Server-Client Communications Right

    - by Zeesponge
    Ok i need some serious help here. I have to make a TCP Server Client. When the Client connects to server using a three stage handshake. AFterwards... while the Client is running in the terminal, the user enters linux shell commands like xinput list, ls -1, ect... something that uses standard output. The server accepts the commands and uses system() (in a fork() in an infinite loop) to run the commands and the standard output is redirected to the client, where the client prints out each line. Afterward the server sends a completion signal of "\377\n". In which the client goes back to the command prompt asking for a new command and closes its connection and exit()'s when inputting "quit". I know that you have to dup2() both the STDOUT_FILENO and STDERR_FILENO to the clients file descriptor {dup2(client_FD, STDOUT_FILENO). Everything works accept when it comes for the client to retrieve system()'s stdout and printing it out... all i get is a blank line with a blinking cursor (client waiting on stdin). I tried all kinds of different routes with no avail... If anyone can help out i would greatly appreciate it TCP SERVER CODE include #include <sys/socket.h> #include <stdio.h> #include <string.h> #include <netinet/in.h> #include <signal.h> #include <unistd.h> #include <stdlib.h> #include <errno.h> //Prototype void handle_client(int connect_fd); int main() { int server_sockfd, client_sockfd; socklen_t server_len, client_len; struct sockaddr_in server_address; struct sockaddr_in client_address; server_sockfd = socket(AF_INET, SOCK_STREAM, 0); server_address.sin_family = AF_INET; server_address.sin_addr.s_addr = htonl(INADDR_ANY); server_address.sin_port = htons(9734); server_len = sizeof(server_address); bind(server_sockfd, (struct sockaddr *)&server_address, server_len); /* Create a connection queue, ignore child exit details and wait for clients. */ listen(server_sockfd, 10); signal(SIGCHLD, SIG_IGN); while(1) { printf("server waiting\n"); client_len = sizeof(client_address); client_sockfd = accept(server_sockfd, (struct sockaddr *)&client_address, &client_len); if(fork() == 0) handle_client(client_sockfd); else close(client_sockfd); } } void handle_client(int connect_fd) { const char* remsh = "<remsh>\n"; const char* ready = "<ready>\n"; const char* ok = "<ok>\n"; const char* command = "<command>\n"; const char* complete = "<\377\n"; const char* shared_secret = "<shapoopi>\n"; static char server_msg[201]; static char client_msg[201]; static char commands[201]; int sys_return; //memset client_msg, server_msg, commands memset(&client_msg, 0, sizeof(client_msg)); memset(&server_msg, 0, sizeof(client_msg)); memset(&commands, 0, sizeof(commands)); //read remsh from client read(connect_fd, &client_msg, 200); //check remsh validity from client if(strcmp(client_msg, remsh) != 0) { errno++; perror("Error Establishing Handshake"); close(connect_fd); exit(1); } //memset client_msg memset(&client_msg, 0, sizeof(client_msg)); //write remsh to client write(connect_fd, remsh, strlen(remsh)); //read shared_secret from client read(connect_fd, &client_msg, 200); //check shared_secret validity from client if(strcmp(client_msg, shared_secret) != 0) { errno++; perror("Invalid Security Passphrase"); write(connect_fd, "no", 2); close(connect_fd); exit(1); } //memset client_msg memset(&client_msg, 0, sizeof(client_msg)); //write ok to client write(connect_fd, ok, strlen(ok)); // dup2 STDOUT_FILENO <= client fd, STDERR_FILENO <= client fd dup2(connect_fd, STDOUT_FILENO); dup2(connect_fd, STDERR_FILENO); //begin while... while read (client_msg) from server and >0 while(read(connect_fd, &client_msg, 200) > 0) { //check command validity from client if(strcmp(client_msg, command) != 0) { errno++; perror("Error, unable to retrieve data"); close(connect_fd); exit(1); } //memset client_msg memset(&client_msg, 0, sizeof(client_msg)); //write ready to client write(connect_fd, ready, strlen(ready)); //read commands from client read(connect_fd, &commands, 200); //run commands using system( ) sys_return = system(commands); //check success of system( ) if(sys_return < 0) { perror("Invalid Commands"); errno++; } //memset commands memset(commands, 0, sizeof(commands)); //write complete to client write(connect_fd, complete, sizeof(complete)); } } TCP CLIENT CODE #include <sys/types.h> #include <sys/socket.h> #include <stdio.h> #include <string.h> #include <netinet/in.h> #include <arpa/inet.h> #include <unistd.h> #include <stdlib.h> #include <errno.h> #include "readline.c" int main(int argc, char *argv[]) { int sockfd; int len; struct sockaddr_in address; int result; const char* remsh = "<remsh>\n"; const char* ready = "<ready>\n"; const char* ok = "<ok>\n"; const char* command = "<command>\n"; const char* complete = "<\377\n"; const char* shared_secret = "<shapoopi>\n"; static char server_msg[201]; static char client_msg[201]; memset(&client_msg, 0, sizeof(client_msg)); memset(&server_msg, 0, sizeof(server_msg)); /* Create a socket for the client. */ sockfd = socket(AF_INET, SOCK_STREAM, 0); /* Name the socket, as agreed with the server. */ memset(&address, 0, sizeof(address)); address.sin_family = AF_INET; address.sin_addr.s_addr = inet_addr(argv[1]); address.sin_port = htons(9734); len = sizeof(address); /* Now connect our socket to the server's socket. */ result = connect(sockfd, (struct sockaddr *)&address, len); if(result == -1) { perror("ACCESS DENIED"); exit(1); } //write remsh to server write(sockfd, remsh, strlen(remsh)); //read remsh from server read(sockfd, &server_msg, 200); //check remsh validity from server if(strcmp(server_msg, remsh) != 0) { errno++; perror("Error Establishing Initial Handshake"); close(sockfd); exit(1); } //memset server_msg memset(&server_msg, 0, sizeof(server_msg)); //write shared secret text to server write(sockfd, shared_secret, strlen(shared_secret)); //read ok from server read(sockfd, &server_msg, 200); //check ok velidity from server if(strcmp(server_msg, ok) != 0 ) { errno++; perror("Incorrect security phrase"); close(sockfd); exit(1); } //? dup2 STDIN_FILENO = server socket fd? //dup2(sockfd, STDIN_FILENO); //begin while(1)/////////////////////////////////////// while(1){ //memset both msg arrays memset(&client_msg, 0, sizeof(client_msg)); memset(&server_msg, 0, sizeof(server_msg)); //print Enter Command, scan input, fflush to stdout printf("<<Enter Command>> "); scanf("%s", client_msg); fflush(stdout); //check quit input, if true close and exit successfully if(strcmp(client_msg, "quit") == 0) { printf("Exiting\n"); close(sockfd); exit(EXIT_SUCCESS); } //write command to server write(sockfd, command, strlen(command)); //read ready from server read(sockfd, &server_msg, 200); //check ready validity from server if(strcmp(server_msg, ready) != 0) { errno++; perror("Failed Server Communications"); close(sockfd); exit(1); } //memset server_msg memset(&server_msg, 0, sizeof(server_msg)); //begin looping and retrieving from stdin, //break loop at EOF or complete while((read(sockfd, server_msg, 200) != 0) && (strcmp(server_msg, complete) != 0)) { //while((fgets(server_msg, 4096, stdin) != EOF) || (strcmp(server_msg, complete) == 0)) { printf("%s", server_msg); memset(&server_msg, 0, sizeof(server_msg)); } } }

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  • Designing a persistent asynchronous TCP protocol

    - by dogglebones
    I have got a collection of web sites that need to send time-sensitive messages to host machines all over my metro area, each on its own generally dynamic IP. Until now, I have been doing this the way of the script kiddie: Each host machine runs an (s)FTP server, or an HTTP(s) server, and correspondingly has a certain port opened up by its gateway. Each host machine runs a program that watches a certain folder and automatically opens or prints or exec()s when a new file of a given extension shows up. Dynamic IP addresses are accommodated using a dynamic DNS service. Each web site does cURL or fsockopen or whatever and communicates directly with its recipient as-needed. This approach has been suprisingly reliable, however obvious issues have come up and the situation needs to be addressed. As stated, these messages are time-sensitive and failures need to be detected within minutes of submission by end-users. What I'm doing is building a messaging protocol. It will run on a machine and connection in my control. As far as the service is concerned, there is no distinction between web site and host machine -- there is only one device sending a message to another device. So that's where I'm at right now. I've got a skeleton server and a skeleton client. They can negotiate high-quality authentication and encryption. The (TCP) connection is persistent and asynchronous, and can handle delimited (i.e., read until \r\n or whatever) as well as length-prefixed (i.e., read exactly n bytes) messages. Unless somebody gives me a better idea, I think I'll handle messages as byte arrays. So I'm looking for suggestions on how to model the protocol itself -- at the application level. I'll mostly be transferring XML and DLM type files, as well as control messages for things like "handshake" and "is so-and-so online?" and so forth. Is there anything really stupid in my train of thought? Or anything I should read about before I get started? Stuff like that -- please and thanks.

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  • TCP RST right after FIN/ACK

    - by Nitzan Shaked
    I am having the weirdest issue: I have a web server which sometimes, only on very specific requests, will send a RST to the client after having sent the FIN datagram. First, a description of the setup: The server runs on an Ubuntu 12.04.1 LTS, which itself is a VM guest inside a Win7 x64 host, in bridged mode. ufw is disabled on the host The client runs on a iOS simulator, which runs on OS X Mountain Lion, which is a VM guest (hackintosh) inside a Win7 x64 host, in bridged mode. Both client and server are on the same LAN, one is connected to the home router via an Ethernet cable, and then other thru WiFi. I happened to glimpse over the server's http logs and found that the client sometimes issuing multiple subsequent identical requests. Further investigation led me to discover that this happens when the server sends a RST, and that the client is simply re-trying. I am attaching several tcpdump's: Good1 is the server-side tcpdump of a good session ("good" meaning no RST was generated). Good3 is another sever-side tcpdump of a good session. (The difference between Good1 and Good3 is the order in which ACK's were sent from the server to the client, ACK'ing the client's request. The client's request arives in 2 segements (specifically: one for the http headers, and another for a body containing an empty json object, "{}"). In Good1, the server ACK's both request segments, using 2 ACK segments, after the second request has arrived. In Good3, the server ACK's each request segment with an ACK segment as soon as the request segment arrives. Not that it should make a difference.) Bad1 is a dump, both client- and server-side, of a bad session. Bad2 is another bad session, this time server-side only. Note that in all "bad" sessions, the server ACK's each request segments immediately after having received it. I've looked at a few other bad sessions, and the situation is the same in all of them. But this is also the behavior in "Good3", so I don't see how that observation helps me, of for that matter why it should matter. I can't find any difference between good and bad sessions, or at least one that I think should matter. My question is: why are those RST's being generated? Or at least: how do I go about debugging this, or providing more info here that'll help? Edit 2 new facts that I have learned: Section 4.2.2.13 of the RFC (1122) (and Wikipedia, in the article "TCP", under "Connection Termination") says that a TCP application on one host may close the connection before it has read all of the data in its socket buffer, and in such a case the TCP on the host will sent a RST to the other side, to let it know that not all the data it has sent has been read. I'm not sure I completely understand this, since closing my side of the connection still allows me to read, no? It also means that I can't write any more. I am not sure this is relevant, though, since I see a RST after FIN. There are multiple complaints of this happening with wsgiref (Python's dev-mode HTTP server), which is exactly what I'm using. I'll keep updating as I find out more. Thanks! ~~~~~~~~~~~~~~~~~~~~ Good1 -- Server Side ~~~~~~~~~~~~~~~~~~~~ 13:28:02.308319 IP 192.168.1.51.51479 > 192.168.1.132.5000: Flags [S], seq 94268074, win 65535, options [mss 1460,nop,wscale 4,nop,nop,TS val 943308864 ecr 0,sackOK,eol], length 0 13:28:02.308336 IP 192.168.1.132.5000 > 192.168.1.51.51479: Flags [S.], seq 1726304574, ack 94268075, win 14480, options [mss 1460,sackOK,TS val 326480982 ecr 943308864,nop,wscale 3], length 0 13:28:02.309750 IP 192.168.1.51.51479 > 192.168.1.132.5000: Flags [.], ack 1, win 8235, options [nop,nop,TS val 943308865 ecr 326480982], length 0 13:28:02.310744 IP 192.168.1.51.51479 > 192.168.1.132.5000: Flags [P.], seq 1:351, ack 1, win 8235, options [nop,nop,TS val 943308865 ecr 326480982], length 350 13:28:02.310766 IP 192.168.1.51.51479 > 192.168.1.132.5000: Flags [P.], seq 351:353, ack 1, win 8235, options [nop,nop,TS val 943308865 ecr 326480982], length 2 13:28:02.310841 IP 192.168.1.132.5000 > 192.168.1.51.51479: Flags [.], ack 351, win 1944, options [nop,nop,TS val 326480983 ecr 943308865], length 0 13:28:02.310918 IP 192.168.1.132.5000 > 192.168.1.51.51479: Flags [.], ack 353, win 1944, options [nop,nop,TS val 326480983 ecr 943308865], length 0 13:28:02.315931 IP 192.168.1.132.5000 > 192.168.1.51.51479: Flags [P.], seq 1:18, ack 353, win 1944, options [nop,nop,TS val 326480984 ecr 943308865], length 17 13:28:02.316107 IP 192.168.1.132.5000 > 192.168.1.51.51479: Flags [FP.], seq 18:684, ack 353, win 1944, options [nop,nop,TS val 326480984 ecr 943308865], length 666 13:28:02.317651 IP 192.168.1.51.51479 > 192.168.1.132.5000: Flags [.], ack 18, win 8234, options [nop,nop,TS val 943308872 ecr 326480984], length 0 13:28:02.318288 IP 192.168.1.51.51479 > 192.168.1.132.5000: Flags [.], ack 685, win 8192, options [nop,nop,TS val 943308872 ecr 326480984], length 0 13:28:02.318640 IP 192.168.1.51.51479 > 192.168.1.132.5000: Flags [F.], seq 353, ack 685, win 8192, options [nop,nop,TS val 943308872 ecr 326480984], length 0 13:28:02.318651 IP 192.168.1.132.5000 > 192.168.1.51.51479: Flags [.], ack 354, win 1944, options [nop,nop,TS val 326480985 ecr 943308872], length 0 ~~~~~~~~~~~~~~~~~~~~ Good3 -- Server Side ~~~~~~~~~~~~~~~~~~~~ 13:28:03.311143 IP 192.168.1.51.51486 > 192.168.1.132.5000: Flags [S], seq 1982901126, win 65535, options [mss 1460,nop,wscale 4,nop,nop,TS val 943309853 ecr 0,sackOK,eol], length 0 13:28:03.311155 IP 192.168.1.132.5000 > 192.168.1.51.51486: Flags [S.], seq 2245063571, ack 1982901127, win 14480, options [mss 1460,sackOK,TS val 326481233 ecr 943309853,nop,wscale 3], length 0 13:28:03.312671 IP 192.168.1.51.51486 > 192.168.1.132.5000: Flags [.], ack 1, win 8235, options [nop,nop,TS val 943309854 ecr 326481233], length 0 13:28:03.313330 IP 192.168.1.51.51486 > 192.168.1.132.5000: Flags [P.], seq 1:351, ack 1, win 8235, options [nop,nop,TS val 943309855 ecr 326481233], length 350 13:28:03.313337 IP 192.168.1.132.5000 > 192.168.1.51.51486: Flags [.], ack 351, win 1944, options [nop,nop,TS val 326481234 ecr 943309855], length 0 13:28:03.313342 IP 192.168.1.51.51486 > 192.168.1.132.5000: Flags [P.], seq 351:353, ack 1, win 8235, options [nop,nop,TS val 943309855 ecr 326481233], length 2 13:28:03.313346 IP 192.168.1.132.5000 > 192.168.1.51.51486: Flags [.], ack 353, win 1944, options [nop,nop,TS val 326481234 ecr 943309855], length 0 13:28:03.327942 IP 192.168.1.132.5000 > 192.168.1.51.51486: Flags [P.], seq 1:18, ack 353, win 1944, options [nop,nop,TS val 326481237 ecr 943309855], length 17 13:28:03.328253 IP 192.168.1.132.5000 > 192.168.1.51.51486: Flags [FP.], seq 18:684, ack 353, win 1944, options [nop,nop,TS val 326481237 ecr 943309855], length 666 13:28:03.329076 IP 192.168.1.51.51486 > 192.168.1.132.5000: Flags [.], ack 18, win 8234, options [nop,nop,TS val 943309868 ecr 326481237], length 0 13:28:03.329688 IP 192.168.1.51.51486 > 192.168.1.132.5000: Flags [.], ack 685, win 8192, options [nop,nop,TS val 943309868 ecr 326481237], length 0 13:28:03.330361 IP 192.168.1.51.51486 > 192.168.1.132.5000: Flags [F.], seq 353, ack 685, win 8192, options [nop,nop,TS val 943309869 ecr 326481237], length 0 13:28:03.330370 IP 192.168.1.132.5000 > 192.168.1.51.51486: Flags [.], ack 354, win 1944, options [nop,nop,TS val 326481238 ecr 943309869], length 0 ~~~~~~~~~~~~~~~~~~~~ Bad1 -- Server Side ~~~~~~~~~~~~~~~~~~~~ 13:28:01.311876 IP 192.168.1.51.51472 > 192.168.1.132.5000: Flags [S], seq 920400580, win 65535, options [mss 1460,nop,wscale 4,nop,nop,TS val 943307883 ecr 0,sackOK,eol], length 0 13:28:01.311896 IP 192.168.1.132.5000 > 192.168.1.51.51472: Flags [S.], seq 3103085782, ack 920400581, win 14480, options [mss 1460,sackOK,TS val 326480733 ecr 943307883,nop,wscale 3], length 0 13:28:01.313509 IP 192.168.1.51.51472 > 192.168.1.132.5000: Flags [.], ack 1, win 8235, options [nop,nop,TS val 943307884 ecr 326480733], length 0 13:28:01.315614 IP 192.168.1.51.51472 > 192.168.1.132.5000: Flags [P.], seq 1:351, ack 1, win 8235, options [nop,nop,TS val 943307886 ecr 326480733], length 350 13:28:01.315727 IP 192.168.1.132.5000 > 192.168.1.51.51472: Flags [.], ack 351, win 1944, options [nop,nop,TS val 326480734 ecr 943307886], length 0 13:28:01.316229 IP 192.168.1.51.51472 > 192.168.1.132.5000: Flags [P.], seq 351:353, ack 1, win 8235, options [nop,nop,TS val 943307886 ecr 326480733], length 2 13:28:01.316242 IP 192.168.1.132.5000 > 192.168.1.51.51472: Flags [.], ack 353, win 1944, options [nop,nop,TS val 326480734 ecr 943307886], length 0 13:28:01.321019 IP 192.168.1.132.5000 > 192.168.1.51.51472: Flags [P.], seq 1:18, ack 353, win 1944, options [nop,nop,TS val 326480735 ecr 943307886], length 17 13:28:01.321294 IP 192.168.1.132.5000 > 192.168.1.51.51472: Flags [FP.], seq 18:684, ack 353, win 1944, options [nop,nop,TS val 326480736 ecr 943307886], length 666 13:28:01.321386 IP 192.168.1.132.5000 > 192.168.1.51.51472: Flags [R.], seq 685, ack 353, win 1944, options [nop,nop,TS val 326480736 ecr 943307886], length 0 13:28:01.322727 IP 192.168.1.51.51472 > 192.168.1.132.5000: Flags [.], ack 18, win 8234, options [nop,nop,TS val 943307891 ecr 326480735], length 0 13:28:01.322733 IP 192.168.1.132.5000 > 192.168.1.51.51472: Flags [R], seq 3103085800, win 0, length 0 13:28:01.323221 IP 192.168.1.51.51472 > 192.168.1.132.5000: Flags [.], ack 685, win 8192, options [nop,nop,TS val 943307892 ecr 326480736], length 0 13:28:01.323231 IP 192.168.1.132.5000 > 192.168.1.51.51472: Flags [R], seq 3103086467, win 0, length 0 ~~~~~~~~~~~~~~~~~~~~ Bad1 -- Client Side ~~~~~~~~~~~~~~~~~~~~ 13:28:11.374654 IP 192.168.1.51.51472 > 192.168.1.132.5000: Flags [S], seq 920400580, win 65535, options [mss 1460,nop,wscale 4,nop,nop,TS val 943307883 ecr 0,sackOK,eol], length 0 13:28:11.375764 IP 192.168.1.132.5000 > 192.168.1.51.51472: Flags [S.], seq 3103085782, ack 920400581, win 14480, options [mss 1460,sackOK,TS val 326480733 ecr 943307883,nop,wscale 3], length 0 13:28:11.376352 IP 192.168.1.51.51472 > 192.168.1.132.5000: Flags [.], ack 1, win 8235, options [nop,nop,TS val 943307884 ecr 326480733], length 0 13:28:11.378252 IP 192.168.1.51.51472 > 192.168.1.132.5000: Flags [P.], seq 1:351, ack 1, win 8235, options [nop,nop,TS val 943307886 ecr 326480733], length 350 13:28:11.379027 IP 192.168.1.51.51472 > 192.168.1.132.5000: Flags [P.], seq 351:353, ack 1, win 8235, options [nop,nop,TS val 943307886 ecr 326480733], length 2 13:28:11.379732 IP 192.168.1.132.5000 > 192.168.1.51.51472: Flags [.], ack 351, win 1944, options [nop,nop,TS val 326480734 ecr 943307886], length 0 13:28:11.380592 IP 192.168.1.132.5000 > 192.168.1.51.51472: Flags [.], ack 353, win 1944, options [nop,nop,TS val 326480734 ecr 943307886], length 0 13:28:11.384968 IP 192.168.1.132.5000 > 192.168.1.51.51472: Flags [P.], seq 1:18, ack 353, win 1944, options [nop,nop,TS val 326480735 ecr 943307886], length 17 13:28:11.385044 IP 192.168.1.51.51472 > 192.168.1.132.5000: Flags [.], ack 18, win 8234, options [nop,nop,TS val 943307891 ecr 326480735], length 0 13:28:11.385586 IP 192.168.1.132.5000 > 192.168.1.51.51472: Flags [FP.], seq 18:684, ack 353, win 1944, options [nop,nop,TS val 326480736 ecr 943307886], length 666 13:28:11.385743 IP 192.168.1.51.51472 > 192.168.1.132.5000: Flags [.], ack 685, win 8192, options [nop,nop,TS val 943307892 ecr 326480736], length 0 13:28:11.385966 IP 192.168.1.132.5000 > 192.168.1.51.51472: Flags [R.], seq 685, ack 353, win 1944, options [nop,nop,TS val 326480736 ecr 943307886], length 0 13:28:11.387343 IP 192.168.1.132.5000 > 192.168.1.51.51472: Flags [R], seq 3103085800, win 0, length 0 13:28:11.387344 IP 192.168.1.132.5000 > 192.168.1.51.51472: Flags [R], seq 3103086467, win 0, length 0 ~~~~~~~~~~~~~~~~~~~~ Bad2 -- Server Side ~~~~~~~~~~~~~~~~~~~~ 13:28:01.319185 IP 192.168.1.51.51473 > 192.168.1.132.5000: Flags [S], seq 1631526992, win 65535, options [mss 1460,nop,wscale 4,nop,nop,TS val 943307889 ecr 0,sackOK,eol], length 0 13:28:01.319197 IP 192.168.1.132.5000 > 192.168.1.51.51473: Flags [S.], seq 2524685719, ack 1631526993, win 14480, options [mss 1460,sackOK,TS val 326480735 ecr 943307889,nop,wscale 3], length 0 13:28:01.320692 IP 192.168.1.51.51473 > 192.168.1.132.5000: Flags [.], ack 1, win 8235, options [nop,nop,TS val 943307890 ecr 326480735], length 0 13:28:01.322219 IP 192.168.1.51.51473 > 192.168.1.132.5000: Flags [P.], seq 1:351, ack 1, win 8235, options [nop,nop,TS val 943307890 ecr 326480735], length 350 13:28:01.322336 IP 192.168.1.132.5000 > 192.168.1.51.51473: Flags [.], ack 351, win 1944, options [nop,nop,TS val 326480736 ecr 943307890], length 0 13:28:01.322689 IP 192.168.1.51.51473 > 192.168.1.132.5000: Flags [P.], seq 351:353, ack 1, win 8235, options [nop,nop,TS val 943307890 ecr 326480735], length 2 13:28:01.322700 IP 192.168.1.132.5000 > 192.168.1.51.51473: Flags [.], ack 353, win 1944, options [nop,nop,TS val 326480736 ecr 943307890], length 0 13:28:01.326307 IP 192.168.1.132.5000 > 192.168.1.51.51473: Flags [P.], seq 1:18, ack 353, win 1944, options [nop,nop,TS val 326480737 ecr 943307890], length 17 13:28:01.326614 IP 192.168.1.132.5000 > 192.168.1.51.51473: Flags [FP.], seq 18:684, ack 353, win 1944, options [nop,nop,TS val 326480737 ecr 943307890], length 666 13:28:01.326710 IP 192.168.1.132.5000 > 192.168.1.51.51473: Flags [R.], seq 685, ack 353, win 1944, options [nop,nop,TS val 326480737 ecr 943307890], length 0 13:28:01.328499 IP 192.168.1.51.51473 > 192.168.1.132.5000: Flags [.], ack 18, win 8234, options [nop,nop,TS val 943307896 ecr 326480737], length 0 13:28:01.328509 IP 192.168.1.132.5000 > 192.168.1.51.51473: Flags [R], seq 2524685737, win 0, length 0 13:28:01.328514 IP 192.168.1.51.51473 > 192.168.1.132.5000: Flags [.], ack 685, win 8192, options [nop,nop,TS val 943307896 ecr 326480737], length 0 13:28:01.328517 IP 192.168.1.132.5000 > 192.168.1.51.51473: Flags [R], seq 2524686404, win 0, length 0

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  • TCP Zero Window with no corresponding Window Update

    - by Gandalf
    I am trying to debug a network issue and am using Wireshark and tcpdump to grab packets from my server. I have one client application that is grabbing all my available connections and then holding them, trying to send A LOT of data and essentially causing an unintentional DOS attack. While debugging I notice that I see my server sending "Window Closed" and "Zero Window" TCP packets - but never sending any "Window Update" packets. I am guessing this is why the client never lets go of the connections (it still has more data to send and is waiting). Has anyone ever seen this type of behavior before? Let's not get into the reasons why I haven't set up an iptables rule to limit concurrent connections (yeah I know). I also recently changed the MTU from 1500 to 9000 - could this have such a negative effect? (Linux) Thanks.

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  • Duplicate incoming TCP traffic on Debian Squeeze

    - by Erwan Queffélec
    I have to test a homebrew server that accepts a lot of incoming TCP traffic on a single port. The protocol is homebrew as well. For testing purposes, I'd like to send this traffic both : - to the production server (say, listening on port 12345) - to the test server (say, listening on port 23456) My clients apps are "dumb" : they never read data back, and the server never replies anyway, my server only accepts connections, and do statistical computations and store/forward/service both raw and computed data. Actually, client apps and hardware are so simple there is no way I can tell clients to send their stream on both servers... And using "fake" clients is not good enough. What could be the simplest solution ? I can of course write an intermediary app that just copy incoming data and send it back to the testing server, pretending to be the client. I have a single server running Squeeze and have total control over it. Thanks in advance for your replies.

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  • AIX network parameters to close TCP sockets of unplugged devices

    - by ADD Geek
    Hi there We have an AIX box, running what we call in banking "ATM Switch" not the ATM networking switch, but the bank ATM driver. where we have some ATM machines connected to two server processes. The problem is, when we disconnect any of these machines, the netstat -na| grep <port number> command shows that the socket established for this disconnected device is still established, we have to manually send a command from the software to make the socket aware that it is not live anymore. Is there a parameter on tcp level to make this connection aware within a minute or two that this device is not connected anymore? we had the following parameters set with root privileges: no -o tcp_keepidle=1000 no -o tcp_keepcnt=2 no -o tcp_keepintvl=150 no -o tcp_finwait2=100 it was originally having the default values. but even after we changed these parameters and restarted the server processes, the problem was still there.

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  • TCP failure on Solaris

    - by anurag kohli
    Hi All, I recently ran into a problem where a Solaris server could not establish a TCP socket on port 2126. From a packet capture I see this (note: A is a Solaris server, B is a router): A sends SYN to B B sends SYN, ACK to A Notice A (Solaris) does not acknowledge the SYN from B. Due to the business impact of the problem, I had to reboot the server to fix the problem. That said, I want to know the next time the problem occurs, what can I do to get a root cause (ie before server reboot)? Thanks in advance.

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  • TCP Proxy on windows supporting SOCK5

    - by acidzombie24
    I been using privoxy just fine for the moment. However now i need to redirect non http traffic through a proxy that supports SOCK5. I looked at RINETD and spent some time googling (which led me to a SF question suggesting RINETD) but i couldnt figure out how to make it work. Specifically how to give it a listening port for my .NET apps to connect to and the SOCK5 proxy addr/port to connect to (.NET does not support using SOCK5 which is why i need a proxy). What is a simple to use proxy on windows? It must support TCP traffic (instead of only http) and supports SOCK5. -edit- portable solution preferred. I should be able to run it on my usb stick under a limited user.

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  • Several Server Errors (No database connect, can't create TCP/IP socket etc

    - by Tobias Baumeister
    My server stops taking requests on my website today. It works for some time, but then the server just stops working and throws several errors: 500 Internal Server Error Warning: mysql_connect(): Can't create TCP/IP socket (105) in [...] on line 7 Couldn't connect to database. Please try again. mysql_connect(): Host [...] is blocked because of many connection errors; unblock with 'mysqladmin flush-hosts' mod_fcgid: can't apply process slot for /var/www/cgi-bin/cgi_wrapper/cgi_wrapper (this is from Error Log) Any ideas what might cause it? operating system is Ubuntu

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  • How to config DNS onto TCP from UDP

    - by Dante Jiang
    Google DNS (8.8.8.8 and 8.8.4.4) are blocked (or polluted) by all ISPs available to me (and DNS by ISPs just return wrong answers for some sensitive sites!!), and it is said that if we change DNS from UDP onto TCP, the problem can be temporarily solved. My question is: how to config that on Windows 7? The solution provided by the original post: Windows 7 Ultimate DnsApi.dll v6.1.7601.17570 .text:6DC08FC8 8B 46 10 mov eax, [esi+10h] .text:6DC08FCB 89 45 F4 mov [ebp+var_C], eax var_C - 2 85A0: 90 90 90 90 90 -> 33 C0 40 EB 25 85C8: 8B 46 10 -> EB D6 40 I have not figure out how the original solution works so far. It needs to modify the .dll file, and the post provides a .dll after modification. However, I wish there was a solution without this kind of hacking.

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  • Which TCP ports to use?

    - by rowatt
    Is there a TCP port range which I can be sure will not be used by anything else for traffic between two machines? If I am reading RFC6335 correctly, I can be sure that no other applications will use specific ports in the Dynamic/Private/Ephemeral range of 49152-65535. However, if I understand correctly, it also states (section 8.1.2) that an application shouldn't assume that any given port in that range is available at any given time, which would mean I can't be 100% sure that it will be unused all the time. Specifically, I want to assign specific SSH traffic to a different port for the security benefit and so I can classify it differently for QoS purposes, and not have to worry about changing the port in the future.

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  • TCP handshake ok, then the client isn't receiving any packets from the server

    - by infgeoax
    Topology: Client ----- Intermediate Device ----- Server Client: win7 Intermediate Device: unknown Server: CentOS 5.8 The problem occurs when the client and server are trying to establish a SSL connection. It happens to one specific port, 2000. I haven't been able to replicate the problem with other port numbers. I captured packets on both client and server. After the TCP handshake, from the client's perspective, it's not receiving ACKs for its previously sent packets so it kept re-sending them. On the server side, however, it did receive those packets and sent ACK packets. The weird thing is, after the server sent those ACKs, it received a [RST, ACK] packet, from the intermediate device, for every packet it sent. What could be the cause?

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  • SSH sometimes screws up connection when terminal overflows?

    - by SeveQ
    I've got a problem with SSH on a Debian Lenny based server (it's a vHost within a Xen environment, booted on a Xen kernel). I hope someone can help me with this. The SSH connection seems somehow getting screwed up frequently when the terminal overflows (new lines beyond the bottom of the terminal, usually forcing it to scroll). The connection gets lost but not regularly disconnected. It nearly always happens when I do the following: an existing SSH connection gets disconnected (regularly) I order putty to reestablish the connection login-prompt appears at the very bottom of the putty terminal window I enter my login-name, press the enter key I'm asked for the password, I enter it, press the enter key and BOOM! Nothing more happens. I have to reconnect again. So it is reproducable. I'm not totally sure if the connection crashes before or after I enter the password. Furthermore it also happens when there is much text to be displayed (for example when I compile something or do an ls -l on a directory with many entries). Using 'screen', however, helps to reduces the frequency of occurence but doesn't solve the problem completely. It's occurence is independent from which terminal software I use. I mostly use putty but it also happens with other clients. I certainly hope somebody can help me solving this problem. Thanks in advance! //edit: I've just made a Wireshark trace of the ssh connection and there is nothing, I repeat, nothing different between the working and the failing connection (at least aside from frame numbers, ports and times that obviously can't be equal). This leads me to the assumption that the error has to happen on the server's side.

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  • Relation between TCP/IP Keep Alive and HTTP Keep Alive timeout values

    - by Suresh Kumar
    I am trying to understand the relation between TCP/IP and HTTP timeout values. Are these two timeout values different or same? Most Web servers allow users to set the HTTP Keep Alive timeout value through some configuration. How is this value used by the Web servers? is this value just set on the underlying TCP/IP socket i.e is the HTTP Keep Alive timeout and TCP/IP Keep Alive Timeout same? or are they treated differently? My understanding is (maybe incorrect): The Web server uses the default timeout on the underlying TCP socket (i.e. indefinite) and creates Worker thread that counts down the specified HTTP timeout interval. When the Worker thread hits zero, it closes the connection.

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