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• Packet flooding while configuring a Debian L2TP/IPSec client?

  - by Joseph B.

  I'm currently at my wits end trying to configure an L2TP over IPSec VPN connection on my Debian using openswan and xl2tp box connecting to a server of unknown configuration. I've managed to successfully establish the connection and everything appears to be working well until I attempt to set the VPN connection as my default route, at which point I see a massive flood of packets simultaneously being transmitted (on the tune of ~1.5 GB in about 2min) until the server drops my connection. Prior to this network traffic on all my interfaces is minimal. According to iftop the majority of this traffic appears to be coming out of port 12, although I can't seem to figure out how to finger a specific process. If I instead just route traffic destined for 74.0.0.0/8 through it I'm able to access Google's servers through the VPN without issue. My xl2tp.conf file is: [lac vpn-nl] lns = example.vpn.com name = myusername pppoptfile = /etc/ppp/options.l2tpd.client My options.l2tpd.client file is: ipcp-accept-local ipcp-accept-remote refuse-eap require-mschap-v2 noccp noauth idle 1800 mtu 1410 mru 1410 usepeerdns lock name myusername password mypassword connect-delay 5000 And my routing table looks like: Destination Gateway Genmask Flags Metric Ref Use Iface 10.5.2.1 * 255.255.255.255 UH 0 0 0 ppp0 10.0.50.0 * 255.255.255.0 U 0 0 0 eth0 10.50.0.0 * 255.255.0.0 U 0 0 0 eth0 10.0.0.0 * 255.255.0.0 U 0 0 0 eth0 192.168.0.0 * 255.255.0.0 U 0 0 0 eth0 loopback * 255.0.0.0 U 0 0 0 lo default * 0.0.0.0 U 0 0 0 ppp0 I'm seeing absolutely nothing in auth.log and syslog during this time and can't seem to find any other log files it might be writing to. Any suggestions would be appreciated!

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• How to determine what program send the packet recorded in Wireshark?

  - by Tono Nam

  I was taking some tutorials on Wireshark in order to analyze the packets sent and received when talking to a web server for purposes of learning. When I start listening/recording packets in Wireshark, there where so many packages being recorded (700 packages per minute). Is it normal to have that much traffic if I have all the programs that will cause traffic such as all browsers, log me in, dropbox, goto meeting, etc., closed? In order to try to solve the problem I am analyzing random packets. Take for instance this filter: I just selected a random IP: 74.125.130.99. So how can I know from what program those packets where created? Also how can I get more info about that communication bwtween my computer (192.168.0.139) and that server (74.125.130.99)? I just selected a random IP from the Wireshark capture. There are also other IPs that I have no idea why they are communicating with my computer. How can I figure that out?

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• Is it possible to cause artificial network packet loss or latency?

  - by nbolton

  I'm trying to reproduce some issues on a deployed application where the MSSQL server and client are running in two separate machines. I think there may be network issues between the two machines, so I'd like to try and reproduce these conditions on two Hyper-V virtual machines (on the same virtual server). Of course, the network for these virtual machines is "local" so it's actually far from the conditions in a live environment. Is there a program I can run on either virtual machine which will degrade the network performance? Or maybe any other work arounds? For example, one way to reproduce the conditions may be to run the VMs on separate Hyper-V servers in geographically dispersed locations (so the SQL traffic goes over VPN or something) -- but this is a little long winded I think. There must be a simpler way.

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• Java ByteBuffer to VB .NET

  - by user1797258

  I have this java code : ByteBuffer p = ByteBuffer.allocate(packet.length - 10 + 14); p.order(ByteOrder.LITTLE_ENDIAN); p.putInt(packet.length); p.putInt(packet.request_id); p.putInt(packet.type); p.put(packet.paylod); p.put((byte) 0); p.put((byte) 0); And i want to translate it to VB .NET I started with this : Dim p(packet.length - 10 + 14) As Byte But after i dont know how to put these variables in the right way

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• Unable to logon to vpn

  - by nitin pande

  My openvpn client log file- The interesting bit: Tue Oct 26 12:32:49 2010 TLS Error: cannot locate HMAC in incoming packet from 67.228.223.12:3389 Tue Oct 26 12:32:49 2010 Fatal TLS error (check_tls_errors_co), restarting Tue Oct 26 12:32:49 2010 TCP/UDP: Closing socket The rest of the log just in case: Tue Oct 26 12:32:35 2010 OpenVPN 2.0.9 Win32-MinGW [SSL] [LZO] built on Oct 1 2006 Tue Oct 26 12:32:48 2010 IMPORTANT: OpenVPN's default port number is now 1194, based on an official port number assignment by IANA. OpenVPN 2.0-beta16 and earlier used 5000 as the default port. Tue Oct 26 12:32:48 2010 Control Channel Authentication: using 'ta.key' as a OpenVPN static key file Tue Oct 26 12:32:48 2010 Outgoing Control Channel Authentication: Using 160 bit message hash 'SHA1' for HMAC authentication Tue Oct 26 12:32:48 2010 Incoming Control Channel Authentication: Using 160 bit message hash 'SHA1' for HMAC authentication Tue Oct 26 12:32:48 2010 LZO compression initialized Tue Oct 26 12:32:48 2010 Control Channel MTU parms [ L:1544 D:168 EF:68 EB:0 ET:0 EL:0 ] Tue Oct 26 12:32:48 2010 Data Channel MTU parms [ L:1544 D:1450 EF:44 EB:135 ET:0 EL:0 AF:3/1 ] Tue Oct 26 12:32:48 2010 Local Options hash (VER=V4): 'ee93268d' Tue Oct 26 12:32:48 2010 Expected Remote Options hash (VER=V4): 'bd577cd1' Tue Oct 26 12:32:48 2010 Attempting to establish TCP connection with 67.228.223.12:3389 Tue Oct 26 12:32:48 2010 TCP connection established with 67.228.223.12:3389 Tue Oct 26 12:32:48 2010 TCPv4_CLIENT link local: [undef] Tue Oct 26 12:32:48 2010 TCPv4_CLIENT link remote: 67.228.223.12:3389 Tue Oct 26 12:32:49 2010 TLS: Initial packet from 67.228.223.12:3389, sid=bd5f79fe 8475497f Tue Oct 26 12:32:49 2010 TLS Error: cannot locate HMAC in incoming packet from 67.228.223.12:3389 Tue Oct 26 12:32:49 2010 Fatal TLS error (check_tls_errors_co), restarting Tue Oct 26 12:32:49 2010 TCP/UDP: Closing socket Tue Oct 26 12:32:49 2010 SIGUSR1[soft,tls-error] received, process restarting Tue Oct 26 12:32:49 2010 Restart pause, 5 second(s) Tue Oct 26 12:32:54 2010 IMPORTANT: OpenVPN's default port number is now 1194, based on an official port number assignment by IANA. OpenVPN 2.0-beta16 and earlier used 5000 as the default port. Tue Oct 26 12:32:54 2010 Re-using SSL/TLS context Tue Oct 26 12:32:54 2010 LZO compression initialized Tue Oct 26 12:32:54 2010 Control Channel MTU parms [ L:1544 D:168 EF:68 EB:0 ET:0 EL:0 ] Tue Oct 26 12:32:54 2010 Data Channel MTU parms [ L:1544 D:1450 EF:44 EB:135 ET:0 EL:0 AF:3/1 ] Tue Oct 26 12:32:54 2010 Local Options hash (VER=V4): 'ee93268d' Tue Oct 26 12:32:54 2010 Expected Remote Options hash (VER=V4): 'bd577cd1' Tue Oct 26 12:32:54 2010 Attempting to establish TCP connection with 67.228.223.12:3389 Tue Oct 26 12:32:54 2010 TCP connection established with 67.228.223.12:3389 Tue Oct 26 12:32:54 2010 TCPv4_CLIENT link local: [undef] Tue Oct 26 12:32:54 2010 TCPv4_CLIENT link remote: 67.228.223.12:3389 Tue Oct 26 12:32:54 2010 TLS: Initial packet from 67.228.223.12:3389, sid=1643b931 ce240d5f Tue Oct 26 12:32:54 2010 TLS Error: cannot locate HMAC in incoming packet from 67.228.223.12:3389 Tue Oct 26 12:32:54 2010 Fatal TLS error (check_tls_errors_co), restarting Tue Oct 26 12:32:54 2010 TCP/UDP: Closing socket Tue Oct 26 12:32:54 2010 SIGUSR1[soft,tls-error] received, process restarting Tue Oct 26 12:32:54 2010 Restart pause, 5 second(s) Tue Oct 26 12:32:59 2010 IMPORTANT: OpenVPN's default port number is now 1194, based on an official port number assignment by IANA. OpenVPN 2.0-beta16 and earlier used 5000 as the default port. Tue Oct 26 12:32:59 2010 Re-using SSL/TLS context Tue Oct 26 12:32:59 2010 LZO compression initialized Tue Oct 26 12:32:59 2010 Control Channel MTU parms [ L:1544 D:168 EF:68 EB:0 ET:0 EL:0 ] Tue Oct 26 12:32:59 2010 Data Channel MTU parms [ L:1544 D:1450 EF:44 EB:135 ET:0 EL:0 AF:3/1 ] Tue Oct 26 12:32:59 2010 Local Options hash (VER=V4): 'ee93268d' Tue Oct 26 12:32:59 2010 Expected Remote Options hash (VER=V4): 'bd577cd1' Tue Oct 26 12:32:59 2010 Attempting to establish TCP connection with 67.228.223.12:3389 Tue Oct 26 12:33:00 2010 TCP connection established with 67.228.223.12:3389 Tue Oct 26 12:33:00 2010 TCPv4_CLIENT link local: [undef] Tue Oct 26 12:33:00 2010 TCPv4_CLIENT link remote: 67.228.223.12:3389 Tue Oct 26 12:33:00 2010 TLS: Initial packet from 67.228.223.12:3389, sid=cd439fb2 d625ca0d Tue Oct 26 12:33:00 2010 TLS Error: cannot locate HMAC in incoming packet from 67.228.223.12:3389 Tue Oct 26 12:33:00 2010 Fatal TLS error (check_tls_errors_co), restarting Tue Oct 26 12:33:00 2010 TCP/UDP: Closing socket Tue Oct 26 12:33:00 2010 SIGUSR1[soft,tls-error] received, process restarting Tue Oct 26 12:33:00 2010 Restart pause, 5 second(s) Tue Oct 26 12:33:05 2010 IMPORTANT: OpenVPN's default port number is now 1194, based on an official port number assignment by IANA. OpenVPN 2.0-beta16 and earlier used 5000 as the default port. Tue Oct 26 12:33:05 2010 Re-using SSL/TLS context Tue Oct 26 12:33:05 2010 LZO compression initialized Tue Oct 26 12:33:05 2010 Control Channel MTU parms [ L:1544 D:168 EF:68 EB:0 ET:0 EL:0 ] Tue Oct 26 12:33:05 2010 Data Channel MTU parms [ L:1544 D:1450 EF:44 EB:135 ET:0 EL:0 AF:3/1 ] Tue Oct 26 12:33:05 2010 Local Options hash (VER=V4): 'ee93268d' Tue Oct 26 12:33:05 2010 Expected Remote Options hash (VER=V4): 'bd577cd1' Tue Oct 26 12:33:05 2010 Attempting to establish TCP connection with 67.228.223.12:3389 Tue Oct 26 12:33:06 2010 TCP connection established with 67.228.223.12:3389 Tue Oct 26 12:33:06 2010 TCPv4_CLIENT link local: [undef] Tue Oct 26 12:33:06 2010 TCPv4_CLIENT link remote: 67.228.223.12:3389 Tue Oct 26 12:33:06 2010 TLS: Initial packet from 67.228.223.12:3389, sid=28f0cb87 69c90cde Tue Oct 26 12:33:06 2010 TLS Error: cannot locate HMAC in incoming packet from 67.228.223.12:3389 Tue Oct 26 12:33:06 2010 Fatal TLS error (check_tls_errors_co), restarting Tue Oct 26 12:33:06 2010 TCP/UDP: Closing socket Tue Oct 26 12:33:06 2010 SIGUSR1[soft,tls-error] received, process restarting Tue Oct 26 12:33:06 2010 Restart pause, 5 second(s) Tue Oct 26 12:33:11 2010 IMPORTANT: OpenVPN's default port number is now 1194, based on an official port number assignment by IANA. OpenVPN 2.0-beta16 and earlier used 5000 as the default port. Tue Oct 26 12:33:11 2010 Re-using SSL/TLS context Tue Oct 26 12:33:11 2010 LZO compression initialized Tue Oct 26 12:33:11 2010 Control Channel MTU parms [ L:1544 D:168 EF:68 EB:0 ET:0 EL:0 ] Tue Oct 26 12:33:11 2010 Data Channel MTU parms [ L:1544 D:1450 EF:44 EB:135 ET:0 EL:0 AF:3/1 ] Tue Oct 26 12:33:11 2010 Local Options hash (VER=V4): 'ee93268d' Tue Oct 26 12:33:11 2010 Expected Remote Options hash (VER=V4): 'bd577cd1' Tue Oct 26 12:33:11 2010 Attempting to establish TCP connection with 67.228.223.12:3389 Tue Oct 26 12:33:11 2010 TCP connection established with 67.228.223.12:3389 Tue Oct 26 12:33:11 2010 TCPv4_CLIENT link local: [undef] Tue Oct 26 12:33:11 2010 TCPv4_CLIENT link remote: 67.228.223.12:3389 Tue Oct 26 12:33:12 2010 TLS: Initial packet from 67.228.223.12:3389, sid=128becf9 f62adf0c Tue Oct 26 12:33:12 2010 TLS Error: cannot locate HMAC in incoming packet from 67.228.223.12:3389 Tue Oct 26 12:33:12 2010 Fatal TLS error (check_tls_errors_co), restarting Tue Oct 26 12:33:12 2010 TCP/UDP: Closing socket Tue Oct 26 12:33:12 2010 SIGUSR1[soft,tls-error] received, process restarting Tue Oct 26 12:33:12 2010 Restart pause, 5 second(s) Tue Oct 26 12:33:17 2010 IMPORTANT: OpenVPN's default port number is now 1194, based on an official port number assignment by IANA. OpenVPN 2.0-beta16 and earlier used 5000 as the default port. Tue Oct 26 12:33:17 2010 Re-using SSL/TLS context Tue Oct 26 12:33:17 2010 LZO compression initialized Tue Oct 26 12:33:17 2010 Control Channel MTU parms [ L:1544 D:168 EF:68 EB:0 ET:0 EL:0 ] Tue Oct 26 12:33:17 2010 Data Channel MTU parms [ L:1544 D:1450 EF:44 EB:135 ET:0 EL:0 AF:3/1 ] Tue Oct 26 12:33:17 2010 Local Options hash (VER=V4): 'ee93268d' Tue Oct 26 12:33:17 2010 Expected Remote Options hash (VER=V4): 'bd577cd1' Tue Oct 26 12:33:17 2010 Attempting to establish TCP connection with 67.228.223.12:3389 Tue Oct 26 12:33:20 2010 TCP/UDP: Closing socket Tue Oct 26 12:33:20 2010 SIGTERM[hard,init_instance] received, process exiting Guys I am extremely sorry for not presenting my error Log properly, please forgive me and give me your valuable advice. I am using windows 7 and I am using openvpn mainly to bypass censorship at UAE. I am using only client config file. Ca.crt file is in config folder Thanks and regards Nitin My error Log with Config1 file Tue Oct 26 21:24:34 2010 OpenVPN 2.0.9 Win32-MinGW [SSL] [LZO] built on Oct 1 2006 Tue Oct 26 21:24:46 2010 IMPORTANT: OpenVPN's default port number is now 1194, based on an official port number assignment by IANA. OpenVPN 2.0-beta16 and earlier used 5000 as the default port. Tue Oct 26 21:24:46 2010 Control Channel Authentication: using 'ta.key' as a OpenVPN static key file Tue Oct 26 21:24:46 2010 Outgoing Control Channel Authentication: Using 160 bit message hash 'SHA1' for HMAC authentication Tue Oct 26 21:24:46 2010 Incoming Control Channel Authentication: Using 160 bit message hash 'SHA1' for HMAC authentication Tue Oct 26 21:24:46 2010 LZO compression initialized Tue Oct 26 21:24:46 2010 Control Channel MTU parms [ L:1544 D:168 EF:68 EB:0 ET:0 EL:0 ] Tue Oct 26 21:24:46 2010 Data Channel MTU parms [ L:1544 D:1450 EF:44 EB:135 ET:0 EL:0 AF:3/1 ] Tue Oct 26 21:24:46 2010 Local Options hash (VER=V4): 'ee93268d' Tue Oct 26 21:24:46 2010 Expected Remote Options hash (VER=V4): 'bd577cd1' Tue Oct 26 21:24:46 2010 Attempting to establish TCP connection with 67.228.223.12:3389 Tue Oct 26 21:24:47 2010 TCP connection established with 67.228.223.12:3389 Tue Oct 26 21:24:47 2010 TCPv4_CLIENT link local: [undef] Tue Oct 26 21:24:47 2010 TCPv4_CLIENT link remote: 67.228.223.12:3389 Tue Oct 26 21:24:47 2010 TLS: Initial packet from 67.228.223.12:3389, sid=4244e662 e5a0572a Tue Oct 26 21:24:47 2010 TLS Error: cannot locate HMAC in incoming packet from 67.228.223.12:3389 Tue Oct 26 21:24:47 2010 Fatal TLS error (check_tls_errors_co), restarting Tue Oct 26 21:24:47 2010 TCP/UDP: Closing socket Tue Oct 26 21:24:47 2010 SIGUSR1[soft,tls-error] received, process restarting client config file: client dev tun proto tcp remote openvpn1.flashvpn.com 3389 float resolv-retry infinite nobind persist-key persist-tun ca ca.crt ns-cert-type server tls-auth ta.key 1 comp-lzo verb 3 mute 20 auth-user-pass route-method exe route-delay 2

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• Will a polled event system cause lag for a server?

  - by Milo

  I'm using a library called ENet. It is a reliable UDP library. The way it works is a polled event system like this: ENetEvent event; /* Wait up to 1000 milliseconds for an event. */ while (enet_host_service (client, & event, 1000) > 0) { switch (event.type) { case ENET_EVENT_TYPE_CONNECT: printf ("A new client connected from %x:%u.\n", event.peer -> address.host, event.peer -> address.port); /* Store any relevant client information here. */ event.peer -> data = "Client information"; break; case ENET_EVENT_TYPE_RECEIVE: printf ("A packet of length %u containing %s was received from %s on channel %u.\n", event.packet -> dataLength, event.packet -> data, event.peer -> data, event.channelID); /* Clean up the packet now that we're done using it. */ enet_packet_destroy (event.packet); break; case ENET_EVENT_TYPE_DISCONNECT: printf ("%s disconected.\n", event.peer -> data); /* Reset the peer's client information. */ event.peer -> data = NULL; } } It waits up to 1000 milliseconds for an event. If I'm hosting say 75 event driven card games and a lobby on the same thread as this code, will it cause any problems. If my understanding is correct, the process will simply sleep until there is an event, when there is one, it will process the event then come back here where potentially 5 or so events have queued up since so enet_host_services would return right away and not cause lag. I have been advised not to use multiple threads, will that be alright like this? Thanks

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• Appropriate design / technologies to handle dynamic string formatting?

  - by Mark W

  recently I was tasked with implementing a way of adding support for versioning of hardware packet specifications to one of our libraries. First a bit of information about the project. We have a hardware library which has classes for each of the various commands we support sending to our hardware. These hardware modules are essentially just lights with a few buttons, and a 2 or 4 digit display. The packets typically follow the format {SOH}AADD{ETX}, where AA is our sentinel action code, and DD is the device ID. These packet specs are different from one command to the next obviously, and the different firmware versions we have support different specifications. For example, on version 1 an action code of 14 may have a spec of {SOH}AADDTEXT{ETX} which would be AA = 14 literal, DD = device ID, TEXT = literal text to display on the device. Then we come out with a revision with adds an extended byte(s) onto the end of the packet like this {SOH}AADDTEXTE{ETX}. Assume the TEXT field is fixed width for this example. We have now added a new field onto the end which could be used to say specify the color or flash rate of the text/buttons. Currently this java library only supports one version of the commands, the latest. In our hardware library we would have a class for this command, say a DisplayTextArgs.java. That class would have fields for the device ID, the text, and the extended byte. The command class would expose a method which generates the string ("{SOH}AADDTEXTE{ETX}") using the value from the class. In practice we would create the Args class as needed, populate the fields, call the method to get our packet string, then ship that down across the CAN. Some of our other commands specification can vary for the same command, on the same version, depending on some runtime state. For example, another command for version 1 may be {SOH}AA{ETX}, where this action code clears all of the modules behind a specific controller device of their text. We may overload this packet to have option fields with multiple meanings like {SOH}AAOC{ETX} where OC is literal text, which tells the controller to only clear text on a specific module type, and to leave the others alone, or the spec could also have an option format of {SOH}AADD{ETX} to clear the text off a a specific device. Currently, in the method which generates the packet string, we would evaluate fields on the args class to determine which spec we will be using when formatting the packet. For this example, it would be along the lines of: if m_DeviceID != null then use {SOH}AADD{ETX} else if m_ClearOCs == true then use {SOH}AAOC{EXT} else use {SOH}AA{ETX} I had considered using XML, or a database to store String.format format strings, which were linked to firmware version numbers in some table. We would load them up at startup, and pass in the version number of the hardwares firmware we are currently using (I can query the devices for their firmware version, but the version is not included in all packets as part of the spec). This breaks down pretty quickly because of the dynamic nature of how we select which version of the command to use. I then considered using a rule engine to possibly build out expressions which could be interpreted at runtume, to evaluate the args class's state, and from that select the appropriate format string to use, but my brief look at rule engines for java scared me away with its complexity. While it seems like it might be a viable solution, it seems overly complex. So this is why I am here. I wouldn't say design is my strongest skill, and im having trouble figuring out the best way to approach this problem. I probably wont be able to radically change the args classes, but if the trade off was good enough, I may be able to convince my boss that the change is appropriate. What I would like from the community is some feedback on some best practices / design methodologies / API or other resources which I could use to accomplish: Logic to determine which set of commands to use for a given firmware version Of those command, which version of each command to use (based on the args classes state) Keep the rules logic decoupled from the application so as to avoid needing releases for every firmware version Be simple enough so I don't need weeks of study and trial and error to implement effectively.

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• Why does my ping command (Windows) results alternate between "timeout" and "network is not reachable"?

  - by Sopalajo de Arrierez

  My Windows is in Spanish, so I will have to paste console outputs in that language (I think that translating without knowing the exact terms used in english versions could give worse results than leaving it as it appears on screen). This is the issue: when pinging a non-existent IP from a WinXP-SP3 machine (clean Windows install, just formatted), I get sometimes a "Timeout" result, and sometimes a "network is not reachable" message. This is the result of: ping 192.168.210.1 Haciendo ping a 192.168.210.1 con 32 bytes de datos: Tiempo de espera agotado para esta solicitud. Respuesta desde 80.58.67.86: Red de destino inaccesible. Respuesta desde 80.58.67.86: Red de destino inaccesible. Tiempo de espera agotado para esta solicitud. Estadísticas de ping para 192.168.210.1: Paquetes: enviados = 4, recibidos = 2, perdidos = 2 (50% perdidos), Tiempos aproximados de ida y vuelta en milisegundos: Mínimo = 0ms, Máximo = 0ms, Media = 0ms 192.168.210.1 does not exist on the network. DHCP client is enabled, and the computer gets assigned those network config by the router. My IP: 192.168.11.2 Netmask: 255.255.255.0 Gateway: 192.168.11.1 DNS: 80.58.0.33/194.224.52.36 This is the output from "route print command": =========================================================================== Rutas activas: Destino de red Máscara de red Puerta de acceso Interfaz Métrica 0.0.0.0 0.0.0.0 192.168.11.1 192.168.11.2 20 127.0.0.0 255.0.0.0 127.0.0.1 127.0.0.1 1 192.168.11.0 255.255.255.0 192.168.11.2 192.168.11.2 20 192.168.11.2 255.255.255.255 127.0.0.1 127.0.0.1 20 192.168.11.255 255.255.255.255 192.168.11.2 192.168.11.2 20 224.0.0.0 240.0.0.0 192.168.11.2 192.168.11.2 20 255.255.255.255 255.255.255.255 192.168.11.2 192.168.11.2 1 255.255.255.255 255.255.255.255 192.168.11.2 3 1 Puerta de enlace predeterminada: 192.168.11.1 =========================================================================== Rutas persistentes: ninguno The output of: ping 1.1.1.1 Haciendo ping a 1.1.1.1 con 32 bytes de datos: Tiempo de espera agotado para esta solicitud. Tiempo de espera agotado para esta solicitud. Tiempo de espera agotado para esta solicitud. Tiempo de espera agotado para esta solicitud. Estadísticas de ping para 1.1.1.1: Paquetes: enviados = 4, recibidos = 0, perdidos = 4 1.1.1.1 does not exist on the network. and the output of: ping 10.1.1.1 Haciendo ping a 10.1.1.1 con 32 bytes de datos: Respuesta desde 80.58.67.86: Red de destino inaccesible. Tiempo de espera agotado para esta solicitud. Tiempo de espera agotado para esta solicitud. Respuesta desde 80.58.67.86: Red de destino inaccesible. Estadísticas de ping para 10.1.1.1: Paquetes: enviados = 4, recibidos = 2, perdidos = 2 (50% perdidos), 10.1.1.1 does not exist on the network. I can do some aproximate translation of what you demand if necessary. I have another computers in the same network (WinXP-SP3 and Win7-SP1), and they have, too, this problem. Gateway (Router): Buffalo WHR-HP-GN (official Buffalo firmware, not DD-WRT). I have some Linux (Debian/Kali) machine in my network, so I tested things on it: ping 192.168.210.1 PING 192.168.210.1 (192.168.210.1) 56(84) bytes of data. From 80.58.67.86 icmp_seq=1 Packet filtered From 80.58.67.86 icmp_seq=2 Packet filtered From 80.58.67.86 icmp_seq=3 Packet filtered From 80.58.67.86 icmp_seq=4 Packet filtered to the non-existing 1.1.1.1 : ping 1.1.1.1 PING 1.1.1.1 (1.1.1.1) 56(84) bytes of data. ^C --- 1.1.1.1 ping statistics --- 153 packets transmitted, 0 received, 100% packet loss, time 153215ms (no response after waiting a few minutes). and the non-existing 10.1.1.1: ping 10.1.1.1 PING 10.1.1.1 (10.1.1.1) 56(84) bytes of data. From 80.58.67.86 icmp_seq=20 Packet filtered From 80.58.67.86 icmp_seq=22 Packet filtered From 80.58.67.86 icmp_seq=23 Packet filtered From 80.58.67.86 icmp_seq=24 Packet filtered From 80.58.67.86 icmp_seq=25 Packet filtered What is going on here? I am posing this question mainly for learning purposes, but there is another reason: when all pings are returning "timeout", it creates an %ERRORLEVEL% value of 1, but if there is someone of "Network is not reachable" type, %ERRORLEVEL% goes to 0 (no error), and this could be inappropriate for a shell script (we can not use ping to detect, for example, if the network is down due to loss of contact with the gateway).

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• How do I configure a C# web service client to send HTTP request header and body in parallel?

  - by Christopher

  Hi, I am using a traditional C# web service client generated in VS2008 .Net 3.5, inheriting from SoapHttpClientProtocol. This is connecting to a remote web service written in Java. All configuration is done in code during client initialization, and can be seen below: ServicePointManager.Expect100Continue = false; ServicePointManager.DefaultConnectionLimit = 10; var client = new APIService { EnableDecompression = true, Url = _url + "?guid=" + Guid.NewGuid(), Credentials = new NetworkCredential(user, password, null), PreAuthenticate = true, Timeout = 5000 // 5 sec }; It all works fine, but the time taken to execute the simplest method call is almost double the network ping time. Whereas a Java test client takes roughly the same as the network ping time: C# client ~ 550ms Java client ~ 340ms Network ping ~ 300ms After analyzing the TCP traffic for a session discovered the following: Basically, the C# client sent TCP packets in the following sequence. Client Send HTTP Headers in one packet. Client Waits For TCP ACK from server. Client Sends HTTP Body in one packet. Client Waits For TCP ACK from server. The Java client sent TCP packets in the following sequence. Client Sends HTTP Headers in one packet. Client Sends HTTP Body in one packet. Client Revieves ACK for first packet. Client Revieves ACK for second packet. Client Revieves ACK for second packet. Is there anyway to configure the C# web service client to send the header/body in parallel as the Java client appears to? Any help or pointers much appreciated.

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• What is the right approach to checksumming UDP packets

  - by mr.b

  I'm building UDP server application in C#. I've come across a packet checksum problem. As you probably know, each packet should carry some simple way of telling receiver if packet data is intact. Now, UDP already has 2-byte checksum as part of header, which is optional, at least in IPv4 world. Alternative method is to have custom checksum as part of data section in each packet, and to verify it on receiver. My question boils down to: is it better to rely on (optional) checksum in UDP packet header, or to make a custom checksum implementation as part of packet data section? Perhaps the right answer depends on circumstances (as usual), so one circumstance here is that, even though code is written and developed in .NET on Windows, it might have to run under platform-independent Mono.NET, so eventual solution should be compatible with other platforms. I believe that custom checksum algorithm would be easily portable, but I'm not so sure about the first one. Any thoughts? Also, shouts about packet checksumming in general are welcome.

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• Are there any configurable parameters to the gpsd?

  - by danatel

  I use the gpsd daemon with my application. Sometimes, the gpsd ceases to work with no apparent reason (clean sky). Even the gpsmon monitor shows no fix. Are there any parameters which must be set? Or is it a hardware problem? I am surprissed that many satellites are visible but the "Stat" bitmap does not contain the bit 7 - ephemeris data available. Should i somewhat pre-configure my position to allow for correct ephemeris data? Here is my gpsmon screen: 127.0.0.1:2947:/dev/ttyS3 SiRF binary> ^[[4~ -¦¦¦¦¦¦¦¦¦¦¦ X ¦¦¦¦¦¦ Y ¦¦¦¦¦¦ Z ¦¦¦¦¦¦¦¦¦¦ North ¦¦¦¦ East ¦¦¦¦¦ Alt ¦¦¦¦¦¦¦¦¦¬ -Pos: 3949260 1166016 4856299 m 49.89411° 16.44920° 1379 m - -Vel: 0.0 0.0 0.0 m/s 0.0 0.0 0.0 climb m/s- -Week+TOW:1578+224837.06 Day: 2 14:27:17.06 Heading: 0.0° 0.0 speed m/s- -Skew: -13.025817 TZ: -7200 HDOP: 0.0 M1:00 M2: 00 - -Fix: 0 = - L¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦ Packet type 2 (0x02) ¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦- -¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¬-¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¬ -Ch PRN Az El Stat C/N ? A --Version: - - 0 2 243 19 003f 40.4 -L¦¦¦¦¦¦¦ Packet Type 6 (0x06) ¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦- - 1 10 249 68 003f 43.0 --¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¬ - 2 13 90 30 003f 40.9 --SVs: 0 Drift: 96506 Bias: 135976716 - - 3 7 66 67 003f 39.8 --Estimated GPS Time: 224837059 - - 4 5 295 49 003d 39.7 -L¦¦¦¦¦¦¦ Packet type 7 (0x07) ¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦- - 5 8 210 69 003f 41.0 --¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¬ - 6 23 96 5 002d 28.0 --Max: 167.570Lat: 132.129Time: 0.075 MS: 02 - - 7 6 43 3 002d 23.1 -L¦¦¦¦¦¦¦ Packet type 9 (0x09) ¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦- - 8 28 163 16 003f 39.8 --¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¬ - 9 0 0 0 0000 0.0 --SVs: 11 = 8 10 7 5 13 2 28 23 3 6 4 - -10 3 55 4 002d 24.7 -L¦¦¦¦¦¦¦ Packet type 13 (0x0D) ¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦- -11 0 0 0 0000 0.0 --¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¬ L¦¦¦ Packet Type 4 (0x04) ¦¦¦--DGPS source: 1 (SBAS) Corrections: 12 - L¦¦¦¦¦¦¦ Packet type 27 (0x1B) ¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦-q

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• NTOP gives warnings on startup

  - by FR6

  I just installed ntop 1.4.4 and when I start it, it give me infinite warnings "packet truncated": ... RRD_DEBUG: umask 0066 RRD_DEBUG: DirPerms 0700 THREADMGMT: RRD: Started thread (t2992630672) for data collection THREADMGMT[t2992630672]: RRD: Data collection thread starting [p30923] INIT: Created pid file (/var/run/ntop.pid) THREADMGMT[t3086329552]: ntop RUNSTATE: INITNONROOT(3) Now running as requested user 'nobody' (99:99) Note: Reporting device initally set to 0 [eth0] (merged) THREADMGMT[t3086329552]: ntop RUNSTATE: RUN(4) THREADMGMT[t2982140816]: NPS(1): Started thread for network packet sniffing [eth0] THREADMGMT[t2982140816]: NPS(eth0): pcapDispatch thread starting [p30923] THREADMGMT[t2982140816]: NPS(eth0): pcapDispatch thread running [p30923] THREADMGMT[t3047009168]: SIH: Idle host scan thread running [p30923] THREADMGMT[t3057499024]: SFP: Fingerprint scan thread running [p30923] **WARNING** packet truncated (8814->8232) **WARNING** packet truncated (10274->8232) **WARNING** packet truncated (8814->8232) **WARNING** packet truncated (8814->8232) ... Do I need to configure something? I tried to access the web interface (http://localhost:3000) but it does not work. Note: I'm on CentOS. EDIT: Not sure if it helps but there is my "ifconfig": eth0 Link encap:Ethernet HWaddr 00:16:76:BC:7E:77 inet addr:192.168.0.221 Bcast:192.168.0.255 Mask:255.255.255.0 inet6 addr: fe80::216:76ff:febc:7e77/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:15496640 errors:0 dropped:0 overruns:0 frame:0 TX packets:19256813 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:836230629 (797.4 MiB) TX bytes:608496148 (580.3 MiB) Memory:dffe0000-e0000000

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• NTOP gives warnings on startup

  - by FR6

  I just installed ntop 1.4.4 and when I start it, it give me infinite warnings "packet truncated": ... RRD_DEBUG: umask 0066 RRD_DEBUG: DirPerms 0700 THREADMGMT: RRD: Started thread (t2992630672) for data collection THREADMGMT[t2992630672]: RRD: Data collection thread starting [p30923] INIT: Created pid file (/var/run/ntop.pid) THREADMGMT[t3086329552]: ntop RUNSTATE: INITNONROOT(3) Now running as requested user 'nobody' (99:99) Note: Reporting device initally set to 0 [eth0] (merged) THREADMGMT[t3086329552]: ntop RUNSTATE: RUN(4) THREADMGMT[t2982140816]: NPS(1): Started thread for network packet sniffing [eth0] THREADMGMT[t2982140816]: NPS(eth0): pcapDispatch thread starting [p30923] THREADMGMT[t2982140816]: NPS(eth0): pcapDispatch thread running [p30923] THREADMGMT[t3047009168]: SIH: Idle host scan thread running [p30923] THREADMGMT[t3057499024]: SFP: Fingerprint scan thread running [p30923] **WARNING** packet truncated (8814->8232) **WARNING** packet truncated (10274->8232) **WARNING** packet truncated (8814->8232) **WARNING** packet truncated (8814->8232) ... Do I need to configure something? I tried to access the web interface (http://localhost:3000) but it does not work. Note: I'm on CentOS. EDIT: Not sure if it helps but there is my "ifconfig": eth0 Link encap:Ethernet HWaddr 00:16:76:BC:7E:77 inet addr:192.168.0.221 Bcast:192.168.0.255 Mask:255.255.255.0 inet6 addr: fe80::216:76ff:febc:7e77/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:15496640 errors:0 dropped:0 overruns:0 frame:0 TX packets:19256813 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:836230629 (797.4 MiB) TX bytes:608496148 (580.3 MiB) Memory:dffe0000-e0000000

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• How does the internet protocol handle network card numbers?

  - by Giorgio

  I know that data packets sent over the internet carry the source and destination IP address, so that the protocol can route the data to the correct destination and keep track of the source address of the packet. But what about the network card address? As far as I know, each network card has a unique identification number. Is this also transmitted with a TCP/IP packet? And when a packet is received at its destination, how is the IP address mapped to a network card number? In other words. On the sender part: does the sender store the sender network card number in the IP packets that it is sending? On the receiver part: which component maps the IP address to the receiver's network card number when a packet is received? E.g., in a home network, does the modem / router map the destination IP address of an incoming packet to a network card number and deliver the packet directly to that network card? A link to documentation on these topics would be of great help.

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• Custumizing Syntax Highlighting in Vim

  - by sixtyfootersdude

  Hey I have defined a few custom file types for vim. I have done this like this: In vimrc: au BufWinEnter,BufRead,BufNewFile *.jak set filetype=jak And then in jak.vim syn match arrows /<-/ syn match arrows /->/ syn match arrows /=>/ syn match arrows /<=/ highlight arrows ctermfg=brown ... This works. (Formatting applies to any file opened with vim with file extension .jak) My question is how I can keep all the current formatting for a file type but add functionality. For example I would like to add this functionality for .vim files: syn keyword yellow yellow highlight yellow ctermfg=yellow ... (so that I can see how my terminal interpenetrates different colors before choosing them.) I have created ~/.vim/syntax/vim.vim (file only contains the above) and put this into my vimrc: au BufWinEnter,BufRead,BufNewFile *.vim set filetype=vim This has no effect. The word yellow is not colored yellow. I have also tried putting my vim.vim file into ~/.vim/after/syntax/vim.vim As suggested here This is the approach that I would like to take. Seems clean and easily maintainable.

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• Receiving data with Winsock

  - by Tamir

  Right now, I'm programming the networking for my online game, and I'm not really sure what to do about receiving data. The problem is that I can't really guess the packet's size, so I thought of reading just 4 bytes from the packet and converting them to an int to know what's the packet's size. Then I'll just create a buffer in that size and receive the rest of the packet, is that a good idea? For your information, I'm using non-blocking i/o.

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• Getting XML parse error in coldfusion. Can the packet returned be validated?

  - by jeff

  Getting an error on occasion on a specific CF page. Offending code listed below. Very odd because when I rebooted CF it went away. Can the XML be checked via XMLValidate to prevent this from happening? Is this some sort of CF bug since the error disappeared after reboot of CF? I have a feeling that the error will resurface at some point. An error occured while Parsing an XML document. The element type "meta" must be terminated by the matching end-tag "". <cfhttp method="get" url="http://bs.mysite.com/webservice/rec/get.sbs?customerId=345S4BE8x&itemId=#product_id#&number=20&ruleId=#product.location_tab_accessories#"> <cfset result = xmlParse(cfhttp.FileContent)> <cfset recs = xmlSearch(result, "/result/thsite/site/itemId")>

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• C# Begin/EndReceive - how do I read large data?

  - by ryeguy

  When reading data in chunks of say, 1024, how do I continue to read from a socket that receives a message bigger than 1024 bytes until there is no data left? Should I just use BeginReceive to read a packet's length prefix only, and then once that is retrieved, use Receive() (in the async thread) to read the rest of the packet? Or is there another way? edit: I thought Jon Skeet's link had the solution, but there is a bit of a speedbump with that code. The code I used is: public class StateObject { public Socket workSocket = null; public const int BUFFER_SIZE = 1024; public byte[] buffer = new byte[BUFFER_SIZE]; public StringBuilder sb = new StringBuilder(); } public static void Read_Callback(IAsyncResult ar) { StateObject so = (StateObject) ar.AsyncState; Socket s = so.workSocket; int read = s.EndReceive(ar); if (read > 0) { so.sb.Append(Encoding.ASCII.GetString(so.buffer, 0, read)); if (read == StateObject.BUFFER_SIZE) { s.BeginReceive(so.buffer, 0, StateObject.BUFFER_SIZE, 0, new AyncCallback(Async_Send_Receive.Read_Callback), so); return; } } if (so.sb.Length > 0) { //All of the data has been read, so displays it to the console string strContent; strContent = so.sb.ToString(); Console.WriteLine(String.Format("Read {0} byte from socket" + "data = {1} ", strContent.Length, strContent)); } s.Close(); } Now this corrected works fine most of the time, but it fails when the packet's size is a multiple of the buffer. The reason for this is if the buffer gets filled on a read it is assumed there is more data; but the same problem happens as before. A 2 byte buffer, for exmaple, gets filled twice on a 4 byte packet, and assumes there is more data. It then blocks because there is nothing left to read. The problem is that the receive function doesn't know when the end of the packet is. This got me thinking to two possible solutions: I could either have an end-of-packet delimiter or I could read the packet header to find the length and then receive exactly that amount (as I originally suggested). There's problems with each of these, though. I don't like the idea of using a delimiter, as a user could somehow work that into a packet in an input string from the app and screw it up. It also just seems kinda sloppy to me. The length header sounds ok, but I'm planning on using protocol buffers - I don't know the format of the data. Is there a length header? How many bytes is it? Would this be something I implement myself? Etc.. What should I do?

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• How to do packet mangling with winsock2 in windows?

  - by httpinterpret

  I'm following examples here, but none of them provides an example on how to modify packets(previously I used winpcap only to found that it can ONLY read packets!). Can someone give me some clue even which function can actually modify incoming/outgoing packets??

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• Vim syntax highlighting: make region only match on one line

  - by sixtyfootersdude

  Hello I have defined a custom file type with these lines: syn region SubSubtitle start=+=+ end=+=+ highlight SubSubtitle ctermbg=black ctermfg=DarkGrey syn region Subtitle start=+==+ end=+==+ highlight Subtitle ctermbg=black ctermfg=DarkMagenta syn region Title start=+===+ end=+===+ highlight Title ctermbg=black ctermfg=yellow syn region MasterTitle start=+====+ end=+====+ highlight MasterTitle cterm=bold term=bold ctermbg=black ctermfg=LightBlue I enclose all of my headings in this kind of document like this: ==== Biggest Heading ==== // this will be bold and light blue ===Sub heading === // this will be yellow bla bla bla // this will be normally formatted However right now when ever I use an equals sign in my code it thinks that it is a title. Is there anyway that I can force a match to be only on one line?

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• Java CORBA Client Disconnects Immediately

  - by Benny

  I have built a Java CORBA application that subscribes to an event server. The application narrows and logs on just fine, but as soon as an event is sent to the client, it breaks with the error below. Please advise. 2010/04/25!13.00.00!E00555!enserver!EventServiceIF_i.cpp!655!PID(7390)!enserver - e._info=system exception, ID 'IDL:omg.org/CORBA/TRANSIENT:1.0' TAO exception, minor code = 54410093 (invocation connect failed; ECONNRESET), completed = NO EDIT: Please note, this only happens when running on some machines. It works on some, but not others. Even on the same platform (I've tried Windows XP/7 and CentOS linux) Some work, some don't... Here is the WireShark output...looks like the working PC is much more interactive with the network compared to the non-working PC. Working PC No. Time Source Destination Protocol Info 62 28.837255 10.10.10.209 10.10.10.250 TCP 50169 > 23120 [SYN] Seq=0 Win=8192 Len=0 MSS=1260 WS=8 63 28.907068 fe80::5de0:8d21:937e:c649 ff02::1:3 LLMNR Standard query A isatap 64 28.907166 10.10.10.209 224.0.0.252 LLMNR Standard query A isatap 65 29.107259 10.10.10.209 10.255.255.255 NBNS Name query NB ISATAP<00> 66 29.227000 10.10.10.250 10.10.10.209 TCP 23120 > 50169 [SYN, ACK] Seq=0 Ack=1 Win=32768 Len=0 MSS=1260 WS=0 67 29.227032 10.10.10.209 10.10.10.250 TCP 50169 > 23120 [ACK] Seq=1 Ack=1 Win=66560 Len=0 68 29.238063 10.10.10.209 10.10.10.250 GIOP GIOP 1.1 Request s=326 id=5 (two-way): op=logon 69 29.291765 10.10.10.250 10.10.10.209 GIOP GIOP 1.1 Reply s=420 id=5: No Exception 70 29.301395 10.10.10.209 10.10.10.250 GIOP GIOP 1.1 Request s=369 id=6 (two-way): op=registerEventStat 71 29.348275 10.10.10.250 10.10.10.209 GIOP GIOP 1.1 Reply s=60 id=6: No Exception 72 29.405250 10.10.10.209 10.10.10.250 TCP 50170 > telnet [SYN] Seq=0 Win=8192 Len=0 MSS=1260 WS=8 73 29.446055 10.10.10.250 10.10.10.209 TCP telnet > 50170 [SYN, ACK] Seq=0 Ack=1 Win=32768 Len=0 MSS=1260 WS=0 74 29.446128 10.10.10.209 10.10.10.250 TCP 50170 > telnet [ACK] Seq=1 Ack=1 Win=66560 Len=0 75 29.452021 10.10.10.209 10.10.10.250 TELNET Telnet Data ... 76 29.483537 10.10.10.250 10.10.10.209 TELNET Telnet Data ... 77 29.483651 10.10.10.209 10.10.10.250 TELNET Telnet Data ... 78 29.523463 10.10.10.250 10.10.10.209 TCP telnet > 50170 [ACK] Seq=4 Ack=5 Win=32768 Len=0 79 29.554954 10.10.10.209 10.10.10.250 TCP 50169 > 23120 [ACK] Seq=720 Ack=505 Win=66048 Len=0 Non-working PC No. Time Source Destination Protocol Info 1 0.000000 10.10.10.209 10.10.10.250 TCP 64161 > 23120 [SYN] Seq=0 Win=8192 Len=0 MSS=1260 WS=8 2 2.999847 10.10.10.209 10.10.10.250 TCP 64161 > 23120 [SYN] Seq=0 Win=8192 Len=0 MSS=1260 WS=8 3 4.540773 Cisco_3c:78:00 Cisco-Li_55:87:72 ARP Who has 10.0.0.1? Tell 10.10.10.209 4 4.540843 Cisco-Li_55:87:72 Cisco_3c:78:00 ARP 10.0.0.1 is at 00:1a:70:55:87:72 5 8.992284 10.10.10.209 10.10.10.250 TCP 64161 > 23120 [SYN] Seq=0 Win=8192 Len=0 MSS=1260

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• Do the Nagle Algorith and Delayed ACK's affect TCP Connection Setup?

  - by Robert S. Barnes

  Do the client's SYN and the servers SYN+ACK get delayed by Nagle? Will the client's ACK of the server's SYN get delayed? Will connect return after rtt+spt or will it take rtt + spt + 2x Nagle Delay? Or more generally, how do the Nagle Algorith and Delayed ACK's affect TCP Connection Setup?

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• How to write custom data to the TCP packet header options field with Java?

  - by snarkov

  As it is defined (see: http://www.freesoft.org/CIE/Course/Section4/8.htm) the TCP header has an 'Options' field. There are a couple of options already defined (see: www.iana.org/assignments/tcp-parameters/) but I want to come up with my very own. (For experimenting/research.) How can I get Java to write (and then read) some custom data to the options field? Bonus question: if it cannot be done with Java. what kind of application can do this? (No, I don't really feel like messing with some kernel-level TCP/IP stack implementation, I want to keep it app level.) Thanks!

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• UDP Tracker not responding

  - by kelton52

  Alright, so I'm trying to connect to UDP trackers using c#, but I never get a response. I also don't get any errors. Here's my code. namespace UDPTester { class MainClass { public static bool messageReceived = false; public static Random Random = new Random(); public static void LOG(string format, params object[] args) { Console.WriteLine (format,args); } public static void Main (string[] args) { LOG ("Creating Packet..."); byte[] packet; using(var stream = new MemoryStream()) { var bc = new MiscUtil.Conversion.BigEndianBitConverter(); using(var br = new MiscUtil.IO.EndianBinaryWriter(bc,stream)) { LOG ("Magic Num: {0}",(Int64)0x41727101980); br.Write (0x41727101980); br.Write((Int32)0); br.Write ((Int32)Random.Next()); packet = stream.ToArray(); LOG ("Packet Size: {0}",packet.Length); } } LOG ("Connecting to tracker..."); var client = new System.Net.Sockets.UdpClient("tracker.openbittorrent.com",80); UdpState s = new UdpState(); s.e = client.Client.RemoteEndPoint; s.u = client; StartReceiving(s); LOG ("Sending Packet..."); client.Send(packet,packet.Length); while(!messageReceived) { Thread.Sleep(1000); } LOG ("Ended"); } public static void StartReceiving(UdpState state) { state.u.BeginReceive(ReceiveCallback,state); } public static void ReceiveCallback(IAsyncResult ar) { UdpClient u = (UdpClient)((UdpState)(ar.AsyncState)).u; IPEndPoint e = (IPEndPoint)((UdpState)(ar.AsyncState)).e; Byte[] receiveBytes = u.EndReceive(ar, ref e); string receiveString = Encoding.ASCII.GetString(receiveBytes); LOG("Received: {0}", receiveString); messageReceived = true; StartReceiving((UdpState)ar.AsyncState); } } public class UdpState { public UdpClient u; public EndPoint e; } } I was using a normal BinaryWriter, but that didn't work, and I read somewhere that it wants it's data in BigEndian. This doesn't work for any of the UDP trackers I've found, any ideas why I'm not getting a response? Did they maybe change the protocol and not tell anyone? HTTP trackers all work fine. Trackers I've tried udp://tracker.publicbt.com:80 udp://tracker.ccc.de:80 udp://tracker.istole.it:80 Also, I'm not interested in using MonoTorrent(and when I was using it, the UDP didn't work anyways). Protocol Sources http://xbtt.sourceforge.net/udp_tracker_protocol.html http://www.rasterbar.com/products/libtorrent/udp_tracker_protocol.html

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• Count of memory copies in *nix systems between packet at NIC and user application?

  - by Michael_73

  Hi there, This is just a general question relating to some high-performance computing I've been wondering about. A certain low-latency messaging vendor speaks in its supporting documentation about using raw sockets to transfer the data directly from the network device to the user application and in so doing it speaks about reducing the messaging latency even further than it does anyway (in other admittedly carefully thought-out design decisions). My question is therefore to those that grok the networking stacks on Unix or Unix-like systems. How much difference are they likely to be able to realise using this method? Feel free to answer in terms of memory copies, numbers of whales rescued or areas the size of Wales ;) Their messaging is UDP-based, as I understand it, so there's no problem with establishing TCP connections etc. Any other points of interest on this topic would be gratefully thought about! Best wishes, Mike

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