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  • Any ideas why Ettercap filters aren't seeing packet data?

    - by Bryan
    I'm using an Ettercap filter to detect a query response coming back from a particular service on a remote machine. When I see a response from the service, I'm searching through the data in the packet to see if an offset is a specific value, and if so I'm changing the value at another offset. Trouble is, when I try this on a new virtual machine I built my Ettercap filter's no longer getting any data in the DATA.data variable available to it. if(ip.proto == TCP && tcp.src == 17867) { msg("Response seen!\n"); if(DATA.data + 2 == "\0x01") { msg("Flag detected!\n"); DATA.data + 5 = 0x09; } } The filter's getting applied to the traffic because "Response seen!" messages get printed out by Ettercap. However, "Flag detected!" messages do not. I think DATA.data is indeed empty because if I change my second "if" statement to check for DATA.data == "" then the "Flag detected!" message gets printed. Any ideas why this may be happening?! Also, if this is the wrong site to be asking questions like this, please let me know. I wasn't sure if it fit better here or somewhere like superuser or serverfault. By the way, this is a cross-post from StackOverflow... I should have posted on this forum instead I think. :)

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  • Can I make a "TCP packet modifier" using tun/tap and raw sockets?

    - by benhoyt
    I have a Linux application that talks TCP, and to help with analysis and statistics, I'd like to modify the data in some of the TCP packets that it sends out. I'd prefer to do this without hacking the Linux TCP stack. The idea I have so far is to make a bridge which acts as a "TCP packet modifier". My idea is to connect to the application via a tun/tap device on one side of the bridge, and to the network card via raw sockets on the other side of the bridge. My concern is that when you open a raw socket it still sends packets up to Linux's TCP stack, and so I couldn't modify them and send them on even if I wanted to. Is this correct? A pseudo-C-code sketch of the bridge looks like: tap_fd = open_tap_device("/dev/net/tun"); raw_fd = open_raw_socket(); for (;;) { select(fds = [tap_fd, raw_fd]); if (FD_ISSET(tap_fd, &fds)) { read_packet(tap_fd); modify_packet_if_needed(); write_packet(raw_fd); } if (FD_ISSET(raw_fd, &fds)) { read_packet(raw_fd); modify_packet_if_needed(); write_packet(tap_fd); } } Does this look possible, or are there other better ways of achieving the same thing? (TCP packet bridging and modification.)

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  • How do I get uri of HTTP packet with winpcap?

    - by Gtker
    Based on this article I can get all incoming packets. /* Callback function invoked by libpcap for every incoming packet */ void packet_handler(u_char *param, const struct pcap_pkthdr *header, const u_char *pkt_data) { struct tm *ltime; char timestr[16]; ip_header *ih; udp_header *uh; u_int ip_len; u_short sport,dport; time_t local_tv_sec; /* convert the timestamp to readable format */ local_tv_sec = header->ts.tv_sec; ltime=localtime(&local_tv_sec); strftime( timestr, sizeof timestr, "%H:%M:%S", ltime); /* print timestamp and length of the packet */ printf("%s.%.6d len:%d ", timestr, header->ts.tv_usec, header->len); /* retireve the position of the ip header */ ih = (ip_header *) (pkt_data + 14); //length of ethernet header /* retireve the position of the udp header */ ip_len = (ih->ver_ihl & 0xf) * 4; uh = (udp_header *) ((u_char*)ih + ip_len); /* convert from network byte order to host byte order */ sport = ntohs( uh->sport ); dport = ntohs( uh->dport ); /* print ip addresses and udp ports */ printf("%d.%d.%d.%d.%d -> %d.%d.%d.%d.%d\n", ih->saddr.byte1, ih->saddr.byte2, ih->saddr.byte3, ih->saddr.byte4, sport, ih->daddr.byte1, ih->daddr.byte2, ih->daddr.byte3, ih->daddr.byte4, dport); } But how do I extract URI information in packet_handler?

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  • Bridging and iptables SNAT conflict

    - by sad_admin
    Hello I am working on a setup here and have it working with one minor exception. Devices on one side of my bridge aren't getting SNAT'd to the Internet. The Diagram / Overview: Primary_Network (Site_A) | | Internet ------- Linux_Bridge_GW (GW) | | Secondary/CoLo Site (Site_B) Here is the setup: 1.) Site_A has all the production servers and workstations. 2.) Site_B has a set of servers that we would like to fail-over to and also serve our internet facing services from. 3.) GW has two interfaces that are trunked and carrying the appropriate VLAN traffic (allow layer-2 propagation of traffic between sites) //this all works perfectly fine. 4.) The problem that is being encountered is, hosts from Site_B have their default GW at Site_A (same subnet) GW does not have IPs on the VLANs that are being passed. 5.) All hosts at Site_A can reach the Internet without problem. 6.) GW has an addresses on a subnet that is ONLY for Internet destined traffic. (This was done so that Websense would not have to parse unnecessary traffic. We use this VLAN as the monitor port's source on the switch where Websense is sitting). What I think is happening: 1.) Packet/Frame comes in on physdev at Site_B destined for Internet. 2.) Kernel sees packet, and forwards it out the other side of the bridge to that host's default GW. 3.) Site_A (containing core-network's Default-GW) sees that packet is destined for a host it doesn't know about, so it sends it to it's default GW (the linux bridge, since it's Internet bound). 4.) The kernel says "Hey, I've seen you before" and therefore doesn't do SNAT'ing on the packet and sends it out to the Internet where it's black-holed. Why I think it's happening: 1.) A tcpdump on the internet facing NIC shows the packet leaving the interface with the private address as it's source. What I would like: 1.) Have the packet SNAT'd. 2.) Something like the below would be awesome a.) packet comes in from Site_B b.) kernel sees that the packet is NOT destined for itself or any private address c.) kernel says "OK, well since you're destined for the Internet I'm going to send you out this interface rather than forward you to your normal default GW that's WAAAY over there." d.) packet comes in from internet and is sent out the appropriate bridge physdev depending on which site the host it's destined for is at. Thanks for any assistance or guidance that you are willing to offer. Best Regards, Sad Admin

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  • Unnecessary Java context switches

    - by Paul Morrison
    I have a network of Java Threads (Flow-Based Programming) communicating via fixed-capacity channels - running under WindowsXP. What we expected, based on our experience with "green" threads (non-preemptive), would be that threads would switch context less often (thus reducing CPU time) if the channels were made bigger. However, we found that increasing channel size does not make any difference to the run time. What seems to be happening is that Java decides to switch threads even though channels aren't full or empty (i.e. even though a thread doesn't have to suspend), which costs CPU time for no apparent advantage. Also changing Thread priorities doesn't make any observable difference. My question is whether there is some way of persuading Java not to make unnecessary context switches, but hold off switching until it is really necessary to switch threads - is there some way of changing Java's dispatching logic? Or is it reacting to something I didn't pay attention to?! Or are there other asynchronism mechanisms, e.g. Thread factories, Runnable(s), maybe even daemons (!). The answer appears to be non-obvious, as so far none of my correspondents has come up with an answer (including most recently two CS profs). Or maybe I'm missing something that's so obvious that people can't imagine my not knowing it... I've added the send and receive code here - not very elegant, but it seems to work...;-) In case you are wondering, I thought the goLock logic in 'send' might be causing the problem, but removing it temporarily didn't make any difference. I have added the code for send and receive... public synchronized Packet receive() { if (isDrained()) { return null; } while (isEmpty()) { try { wait(); } catch (InterruptedException e) { close(); return null; } if (isDrained()) { return null; } } if (isDrained()) { return null; } if (isFull()) { notifyAll(); // notify other components waiting to send } Packet packet = array[receivePtr]; array[receivePtr] = null; receivePtr = (receivePtr + 1) % array.length; //notifyAll(); // only needed if it was full usedSlots--; packet.setOwner(receiver); if (null == packet.getContent()) { traceFuncs("Received null packet"); } else { traceFuncs("Received: " + packet.toString()); } return packet; } synchronized boolean send(final Packet packet, final OutputPort op) { sender = op.sender; if (isClosed()) { return false; } while (isFull()) { try { wait(); } catch (InterruptedException e) { indicateOneSenderClosed(); return false; } sender = op.sender; } if (isClosed()) { return false; } try { receiver.goLock.lockInterruptibly(); } catch (InterruptedException ex) { return false; } try { packet.clearOwner(); array[sendPtr] = packet; sendPtr = (sendPtr + 1) % array.length; usedSlots++; // move this to here if (receiver.getStatus() == StatusValues.DORMANT || receiver.getStatus() == StatusValues.NOT_STARTED) { receiver.activate(); // start or wake up if necessary } else { notifyAll(); // notify receiver // other components waiting to send to this connection may also get // notified, // but this is handled by while statement } sender = null; Component.network.active = true; } finally { receiver.goLock.unlock(); } return true; }

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  • How to capture each frame of a USB webcam using VB.net?

    - by Kevin Boyd
    While I have got some leads from an older SO post and from this site, I haven't been able to figure out how to capture each frame of a web-cam. What I would like to do is something like this capture a frame then do some image processing on it and display the output and then move on to the next frame. Can I can access to web-cam frame events or is there any efficient way to achieve this?

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  • How to use web camera in android emulator to capture a live image?

    - by Kumar
    Hi,As far as i know, Android emulator doesn't have a camera .To capture a live image we have to use web camera.I have seen code in this web site "http://www.tomgibara.com/android/camera-source" to use web camera in android emulator to capture a image but, i don't how to use this code.I am new to this field , can any one help me how to do it. regards, s.kumaran.

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  • how can I capture **http response** from twitter.com? ( ruby + twitter gem)

    - by Radek
    I opened a question how can I capture response from twitter.com? ( ruby + twitter gem) to know if my update was successful. It is working fine... But I would like to know how I can capture HTTP Response Codes and Errors oauth = Twitter::OAuth.new('consumer token', 'consumer secret') oauth.authorize_from_access('access token', 'access secret') client = Twitter::Base.new(oauth) response = client.update('Heeeyyyyoooo from Twitter Gem!')

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  • ASP.NET - Take a screen capture of a particular area of the screen?

    - by hamlin11
    Is it possible to take a screen capture of a particular area of a web-page from the web-page's own ASP.NET code? I need to display 6 images that are stacked on top of one another using CSS, and I'd like to offer the user the ability to right-click save-as if possible by stacking the screen capture on top top of the original image stack. Any thoughts? Thanks

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  • Thank You for a Great Welcome for Oracle GoldenGate 11g Release 2

    - by Irem Radzik
    Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:Calibri; mso-fareast-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} Yesterday morning we had two launch webcasts for Oracle GoldenGate 11g Release 2. I had the pleasure to present, as well as moderate the Q&A panels in both of these webcasts. Both events had hundreds of live attendees, sending us over 150 questions. Even though we left 30 minutes for Q&A, it was not nearly enough time to address for all the insightful questions our audience sent. Our product management team and I really appreciate the interaction we had yesterday and we are starting to respond back with outstanding questions today. Oracle GoldenGate’s new release launch also had great welcome from the media. You can find the links for various articles on the new release below: ITBusinessEdge Oracle Embraces Cross-Platform Data Integration Information Week: Oracle Real-Time Advance Taps Compressed Data Integration Developer News, Oracle GoldenGate Adds Deeper Oracle Integration, Extends Real-Time Performance CIO, Oracle GoldenGate Buddies Up with Sibling Software DBTA, Real-Time Data Integration: Oracle GoldenGate 11g Release 2 Now Available CBR Oracle unveils GoldenGate 11g Release 2 real-time data integration application In this blog, I want to address some of the frequently asked questions that came up during the webcasts. You can find the top questions and their answers along with related resources below. We will continue to address frequently asked questions via future blogs. Q: Will the new Integrated Capture for Oracle Database replace the Classic Capture? If not, which one do I use when? A: No, Classic Capture will be around for long time. Core platform specific features, bug fixes, and patches will be available for both Capture processes.Oracle Database specific features will be only available in the Integrated Capture. The Integrated Capture for Oracle Database is an option for users that need to capture data from compressed tables or need support for XML data types, XA on RAC. Users who don’t leverage these features should continue to use our Classic Capture. For more information on Oracle GoldenGate 11g Release 2 I recommend to check out the White paper: Oracle GoldenGate 11gR2 New Features as well as other technical white papers we have on OTN.                                                         For those of you coming to OpenWorld, please attend the related session: Extracting Data in Oracle GoldenGate Integrated Capture Mode, Monday Oct 1st 1:45pm Moscone South – 102 to learn more about this new feature. Q: What is new in Conflict Detection and Resolution? And how does it work? A: There are now pre-built functions to identify the conditions under which an error occurs and how to handle the record when the condition occurs. Error conditions handled include inserts into a target table where the row already exists, updates or deletes to target table rows that exist, but the original source data (before columns) do not match the existing data in the target row, and updates or deletes where the row does not exist in the target database table.Foreach of these conditions a method to handle the error is specified.  Please check out our recent blog on this topic and the White paper: Oracle GoldenGate 11gR2 New Features white paper.  Also, for those attending OpenWorld please attend the session: Best Practices for Conflict Detection and Resolution in Oracle GoldenGate for Active/Active-  Wednesday Oct 3rd  3:30pm Mascone 3000 Q: Does Oracle GoldenGate Veridata and the Management Pack require additional licenses, or is it incorporated with the GoldenGate license? A: Oracle GoldenGate Veridata and Oracle Management Pack for Oracle GoldenGate are additional products and require separate licenses. Please check out Oracle's price list here. Q: Does GoldenGate - Oracle Enterprise Manager Plug-in require additional license? A: Oracle Enterprise Manager Plug-in is included in the Oracle Management Pack for Oracle GoldenGate license, which is separate from Oracle GoldenGate license. There is no separate license for the Enterprise Manager Plug-in by itself. Oracle GoldenGate Monitor, Oracle GoldenGate Director, and Enterprise Manager Plug-in are included in the Management Pack for Oracle GoldenGate license. Please check out Management Pack for Oracle GoldenGate data sheet for more info on this product bundle. Q: Is Oracle GoldenGate replacing Oracle Streams product? A: Oracle GoldenGate is the strategic data replication product. Therefore, Oracle Streams will continue to be supported, but will not be actively enhanced. Rather, the best elements of Oracle Streams will be added to Oracle GoldenGate. Conflict management is one of them and with the latest release Oracle GoldenGate has a more advanced conflict management offering. Current customers depending on Oracle Streams will continue to be fully supported. Q: How is Oracle GoldenGate different than Oracle Data Integrator? A: Oracle Data Integrator is designed for fast bulk data movement and transformation between heterogeneous systems, while GoldenGate is designed for real-time movement of transactions between heterogeneous systems. These two products are completely complementary where GoldenGate provides low-impact real-time change data capture and delivery to a staging area on the target. And Oracle Data Integrator transforms this data and loads the DW tables. In fact, Oracle Data Integrator integrates with GoldenGate to use GoldenGate’s Capture process as one option for its CDC mechanism. We have several customers that deployed GoldenGate and ODI together to feed real-time data to their data warehousing solutions. Please also check out Oracle Data Integrator Changed Data Capture with Oracle GoldenGate Data Sheet (PDF). Thank you again very much for welcoming Oracle GoldenGate 11g Release 2 and stay in touch with us for more exciting news, updates, and events.

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  • Are there any wireless webcams/cameras that Windows will recognize as a capture device?

    - by Keithius
    I'd like to have a webcam in a different room from my computer, and the distance means USB is out of the question. I know there are many wireless cameras, but what I can't seem to find out is if any of them would be recognized by Windows as a capture device (just like a locally connected USB webcam). Most of the wireless cameras I can find (e.g., D-Link DCS920; Cisco-Linksys WVC54GCA, etc.) can all stream video directly from the camera itself, which is fine if you're using the camera as a "security" camera (for private use only), but not for other uses (say, sending the video to an online video streaming service, e.g., Ustream). It seems like this should be possible; after all, wireless (WiFi) printers with scanners are recognized by Windows. Are there any wireless (WiFi) cameras out there that would be recognized by Windows as a capture device in the same way as a USB webcam would? Alternatively, a camera that's not wireless (e.g., connects via Ethernet) would do the trick too - but I imagine if anyone is going to make a remote camera like this, they'd go the extra step and make it wireless, too.

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  • Python: Socket set source port number

    - by beratch
    Hi all, I'd like to send a specific UDP broadcast packet.. unfortunatly i need to send the udp packet from a very specific port for all packet I send. Let say I broadcast via UDP "BLABLAH", the server will only answer if my incoming packet source port was 1444, if not the packet is discarded. My broadcast socket setup look like this : s = socket(AF_INET,SOCK_DGRAM) s.setsockopt(SOL_SOCKET, SO_BROADCAST, 1) How can i do that (set the source port) in python ? Thanks!

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  • C# listview add items

    - by Eyla
    Greetings, I have a method to capture packets. after capturing I want to add each packet as a row in listview in runting time so as soon as I capture packet I want to add it to the list view. the problem that when I use items.Add() I will get overload argument error. please advice!! here is my code: private void packetCapturingThreadMethod() { Packet packet = null; int countOfPacketCaptures = 0; while ((packet = device.GetNextPacket()) != null) { packet = device.GetNextPacket(); if (packet is TCPPacket) { TCPPacket tcp = (TCPPacket)packet; myPacket tempPacket = new myPacket(); tempPacket.packetType = "TCP"; tempPacket.sourceAddress = Convert.ToString(tcp.SourceAddress); tempPacket.destinationAddress = Convert.ToString(tcp.DestinationAddress); tempPacket.sourcePort = Convert.ToString(tcp.SourcePort); tempPacket.destinationPort = Convert.ToString(tcp.DestinationPort); tempPacket.packetMessage = Convert.ToString(tcp.Data); packetsList.Add(tempPacket); string[] row = { packetsList[countOfPacketCaptures].packetType, packetsList[countOfPacketCaptures].sourceAddress, packetsList[countOfPacketCaptures].destinationAddress, packetsList[countOfPacketCaptures].sourcePort, packetsList[countOfPacketCaptures].destinationPort, packetsList[countOfPacketCaptures].packetMessage }; try { listView1.Items.Add(packetsList[countOfPacketCaptures].packetType, packetsList[countOfPacketCaptures].sourceAddress, packetsList[countOfPacketCaptures].destinationAddress, packetsList[countOfPacketCaptures].sourcePort, packetsList[countOfPacketCaptures].destinationPort, packetsList[countOfPacketCaptures].packetMessage) ; countOfPacketCaptures++; lblCapturesLabels.Text = Convert.ToString(countOfPacketCaptures);} catch (Exception e) { } } else if (packet is UDPPacket) { UDPPacket udp = (UDPPacket)packet; myPacket tempPacket = new myPacket(); tempPacket.packetType = "UDP"; tempPacket.sourceAddress = Convert.ToString(udp.SourceAddress); tempPacket.destinationAddress = Convert.ToString(udp.DestinationAddress); tempPacket.sourcePort = Convert.ToString(udp.SourcePort); tempPacket.destinationPort = Convert.ToString(udp.DestinationPort); tempPacket.packetMessage = Convert.ToString(udp.Data); packetsList.Add(tempPacket); string[] row = { packetsList[countOfPacketCaptures].packetType, packetsList[countOfPacketCaptures].sourceAddress, packetsList[countOfPacketCaptures].destinationAddress, packetsList[countOfPacketCaptures].sourcePort, packetsList[countOfPacketCaptures].destinationPort, packetsList[countOfPacketCaptures].packetMessage }; try { dgwPacketInfo.Rows.Add(row); countOfPacketCaptures++; lblCapturesLabels.Text = Convert.ToString(countOfPacketCaptures); } catch (Exception e) { } } } }

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  • Python and libpcap. find source mac address of packet.

    - by Shamanu4
    Hello! I'm writing python program to build mac-address cache using pcap. But pcap module for python has no good documentation. I have found this page http://pylibpcap.sourceforge.net/ with code example and it works fine. Can anybody modify this example to make it able to show the source mac-address for each packet? Or point me to the documentation where I can read about it ...

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  • How do I modify a HTTP response packet with winpcap?

    - by httpinterpret
    There are two problems here: What if content is encoded:gzip... Do I also need to change the header part to make the HTTP packet valid(checksums if any?) UPDATE Can someone with actual experience elaborate the steps involved? I'm using winpcap and bpf tcp and src port 80 to filter the traffic,so my job lies in this callback function: void packet_handler(u_char *param, const struct pcap_pkthdr *header, const u_char *pkt_data)

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  • iphone problem receiving UDP packets

    - by SooDesuNe
    I'm using sendto() and recvfrom() to send some simple packets via UDP over WiFI. I've tried using two phones, and a simulator, the results I'm getting are: Packets sent from phones - recieved by simulator Packets sent from simulator - simulator recvfrom remains blocking. Packets sent from phones - other phone recvfrom remains blocking. I'm not sure how to start debugging this one, since the simulator/mac is able to receive the the packets, but the phones don't appear to be getting the message. A slight aside, do I need to keep my packets below the MTU for my network? Or is fragmentation handled by the OS or some other lower level software? UPDATE: I forgot to include the packet size and structure. I'm transmitting: typedef struct PacketForTransmission { int32_t packetTypeIdentifier; char data[64]; // size to fit my biggest struct } PacketForTransmission; of which the char data[64] is: typedef struct PacketHeader{ uint32_t identifier; uint32_t datatype; } PacketHeader; typedef struct BasePacket{ PacketHeader header; int32_t cardValue; char sendingDeviceID[41]; //dont forget to save room for the NULL terminator! } BasePacket; typedef struct PositionPacket{ BasePacket basePacket; int32_t x; int32_t y; } PositionPacket; sending packet is like: PositionPacket packet; bzero(&packet, sizeof(packet)); //fill packet with it's associated data PacketForTransmission transmissionPacket; transmissionPacket.packetTypeIdentifier = kPositionPacketType; memcpy(&transmissionPacket.data, (void*)&packet, sizeof(packet)); //put the PositionPacket into data[64] size_t sendResult = sendto(_socket, &transmissionPacket, sizeof(transmissionPacket), 0, [address bytes], [address length]); NSLog(@"packet sent of size: %i", sendResult); and recieving packets is like: while(1){ char dataBuffer[8192]; struct sockaddr addr; socklen_t socklen = sizeof(addr); ssize_t len = recvfrom(_socket, dataBuffer, sizeof(dataBuffer), 0, &addr, &socklen); //continues blocking here NSLog(@"packet recieved of length: %i", len); //do some more stuff }

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  • How does one capture H.323 voice traffic on a VOIP network?

    - by Chris Holmes
    What I am trying to do is capture the WAV data of a phone conversation on a VOIP network using SharpPCap/PCap.Net. We are using the H.323 recommendation and my understanding is that voice data is located in the RTP packets. However, there is no way to heuristically determine if a UDP packet is a RTP packet, so we have to do more work before we can capture the data. The H.323 recommendation apparently uses a lot of traffic on specific TCP ports to negotiate the call before the WAV data is sent via RTP. However, I am having very little luck determining what data is actually sent on those TCP ports, when it is sent, what the packets look like, how to handle it, etc. If anyone has any information on how to go about this I'd really appreciate it. My Google-Fu seems to be failing me on this one.

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  • Mac & Photoshop: Screen capture of an application then pasting it into a new document in photoshop i

    - by maytheschwartzbewithyou
    This used to work perfectly up until about a month or two ago. When doing a screen capture onto the clipboard (cmd + ctr + shift + 4) and pasting it into a new document in Photoshop (only in photoshop, pasting it elsewhere like mail works fine), the drop shadow around the application doesn't look right. What can i do to fix this? Thanks. Pasting into photoshop from clipboard. http://i49.tinypic.com/2el5h6d.jpg

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  • Upcasting without any added data fields.

    - by Benjamin Manns
    In my project I have a generic Packet class. I would like to be able to upcast to other classes (like LoginPacket or MovePacket). The base class contains a command and arguments (greatly simplified): public class Packet { public String Command; public String[] Arguments; } I would like to have be able to convert from Packet to LoginPacket (or any other) based on a check if Packet.Command == "LOGIN". The login packet would not contain any new data members, but only methods for accessing specific arguments. For example: public class LoginPacket : Packet { public String Username { get { return Arguments[0]; } set { Arguments[0] == value; } } public String Password { get { return Arguments[1]; } set { Arguments[1] == value; } } } It would be great if I could run a simple code that would cast from Packet to LoginPacket with something like LoginPacket _Login = (LoginPacket)_Packet;, but that throws a System.InvalidCastException. It seems like this would be an easy task, as no new data is included, but I can't figure out any other way than copying everything from the Packet class to a new LoginPacket class.

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  • ICMP Redirect Theory VS. Application

    - by joeqwerty
    I'm trying to watch ICMP redirects in a lab using Cisco Packet Tracer (version 5.3.2) and I'm not seeing them, which leads me to believe that either my lab configuration isn't correct or my understanding of ICMP redirects isn't correct or that Packet Tracer doesn't support/use ICMP redirects. Here's what I believe to be true regarding ICMP redirects: Routers send ICMP redirects when all of these conditions are met: The interface on which the packet comes into the router is the same interface on which the packet gets routed out. The subnet or network of the source IP address is on the same subnet or network of the next-hop IP address of the routed packet. The datagram is not source-routed. The router kernel is configured to send redirects. I have the lab set up in Cisco Packet Tracer as displayed in the image and would expect to see an ICMP redirect from Router1 when pinging from PC1 to PC3. I'm not seeing the ICMP redirect and it looks like Router1 is actually routing all of the packets via Router2. I have IP ICMP debugging enabled on Router1 (and Router2) and I'm not seeing any ICMP redirect activity in either console. I'm also not seeing a route to the PC3 network in the routing table on PC1, which I think confirms that the ICMP redirect is not occurring. I'm using only static routing on Routers 1 and 2. Is my understanding of ICMP redirects incorrect, or is there a problem with my lab configuration or does Packet Tracer not support/use ICMP redirects?

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