Stun protocol wireshark

RTP, the real-time transport protocol. 9. 0, it only supported saving audio using the G. Wireshark uses the same syntax for capture filters as tcpdump, WinDump, Analyzer, and any other program that uses the libpcap/WinPcap library. Step 4: Identifying the IP Address. The NetBIOS Name Service is part of the NetBIOS-over-TCP protocol suite, see the NetBIOS page for further information. I hope wireshark community definitely will help me for my project. Feedback. Article. C++ is the fastest execution but most difficult to learn and use. 0. Versions affected: 0. IGMP: IP multicasting. - amwalding/wireshark_profiles Wireshark: The world's most popular network protocol analyzer Jul 5, 2014 · The IP address of the STUN packet will be different than the IP address placed in the payload by the STUN server (the address the server sees - usually the NATed address). Fire up wireshark, start capturing. Jun 16, 2015 · STUN is used to resolve the public IP of a device running behind a NAT, to solve problems such as one-way audio during a phone call or phone registration issues when trying to register to a VoIP or an IP PBX residing on a different network. Yep, that's it. Hi there, I have 2 camera's both streaming video. (libpcap itself has an udp filter, but it only understands very few protocols. May 28, 2015 · One Answer: 0. Protocol field name: stun2 Versions: 1. Endpoints. method==0x0001’ to see all Binding Requests and Responses, or ‘stun. Make a call to the person whose IP address you wish to discover. This list is no longer active. 4 Back to Display Filter Reference Jan 2, 2024 · After transfer is finished, we will use Wireshark I/O Graph function to plot the data which will give us the idea of how much bandwidth we used. If you need a display filter for a specific Messages generated by Wireshark are usually placed in square brackets (“ []”). Wireshark University EU. A Teams media flow (that is Sep 30, 2014 · Analysis of STUN servers listed in the Stop Malvertising report that were employed by malware over the past year revealed that the most popular was stunserver. STUN is common to see in connection setup and as a keep-alive mechanism between nodes of a voip/p2p session. 105. Wireshark is supported by the Wireshark Foundation . While analyzing the traffic with WireShark, we discovered that more than 90% of the traffic consists of STUN protocol packets. But when I wireshark the packets, both streams (RTP packets) look the same. pcap: STUN client <-> server packet exchange Duplicate of issue #2376 (closed) To upload designs, you'll need to enable LFS and have an admin enable hashed storage. On some systems, the IEEE 802. We know that Hangouts uses the STUN, RTP, RTCP and SRTP protocols because it requires having these ports open, and if we decode the data packets, RTP data are obtained. net. Versions: 1. Interoperability restrictions. 0/4 reserved network block. Please provide me a sample captured pcap file and wireshark open source code for the STUN and STUN2 protocols. Candidates are ranked with host > srflx / prflx > relay and UDP > TCP. Please support my work - see the readme. Scroll down to RTP. the Apache HTTP server ), which in return will issue a HTTP response. Look through the list for information related to the STUN protocol, and you'll find the IP address of the user who received the call. Network layer (routing): Endpoints. Sep 20, 2022 · Odder still is the value of the XOR_MAPPED_ADDRESS returned by the STUN server, as it is in the middle of the 240. Steps are below. the below window will appear. Ethereal recognizes UDP packets as STUN packets if Nov 20, 2023 · Open connectivity to TCP ports 80 and 443, and to UDP ports 3478 (STUN), 3479 (Audio), 3480 (Video), and 3481 (sharing/VBSS) are required. org, which held the greatest lead at 69 samples (6%), with the immediate runner up at 56 samples (5%). \n \n. So it is expected to have STUN packets in your capture trace. Now perform the steps in Capturing RTP streams section but skip the Decode As steps (2-4). HSR: High-availability Seamless Redundancy: A protocol for network redundancy. Always make sure that you have configured only one secondary interface per stun-group, unless you are configuring sdlc-tg. Two separate CNAME records are returned for this query: pipe. ANNOUNCEMENT: Live Wireshark University & Allegro Packets online APAC Wireshark Training Session Application Data Protocol: Character string: 3. After we determined that this packet is STUN packet, our steps will be: Wireshark's STUN/TURN dissector is, as indicated, dissecting the RTP packets as TURN packets. Unfortunately, it is pretty common to have different flavours in the same capture file, or even in the same packet (with STUN messages encapsulated in a TURN tunnel), so a global preference applied to the entire file might not provide enough flexibility. From: bugzilla-daemon; Prev by Date: [Wireshark-bugs] [Bug 2688] Mojito Protocol Dissestor Plugin; Next by Date: [Wireshark-bugs] [Bug 2837] STUN protocol decodes from Client to Server not recognised as STUN Feb 14, 2019 · The first task is the validation of the STUN binding request message and the generation of the response. Oct 3, 2023 · To use this script effe cti vely, follow these steps: Install Telegram Desktop for Linux or Mac. So you'll be capturing everything, but filtering the displayed list. 0 to 1. An overview of the capture filter syntax can be found in the User's Guide. Wireshark Wiki. method==0x0001 and stun. asked May 6, 2015 at 9:47. The TCP dissector could hang or crash while reassembling HTTP packets. We would like to show you a description here but the site won’t allow us. 0 release. Please file a bug at the Wireshark Bugzilla, and attach a capture file containing the mis-dissected packets. DisplayFilters. A HTTP client (e. 1 - Ethereal 0. Figure 3:Screen shot to start wireshark. org to 65. 274 7 21. A network endpoint is the logical endpoint of separate protocol traffic of a specific protocol layer. This section specifies the processing of Simple Traversal of UDP through NAT (STUN) binding request messages by the two endpoints. Here’s an example of captured STUN authentication using Wireshark: An attacker could now perform NAT traversal and potentially create channels to access internal systems from the outside. 15 is not decoding both of the STUN exchanges. 711 codec; from 3. 0 it supports saving audio using any codec with 8000 Hz sampling. Note that what makes it work is changing ip. IEEE_802. aria. You can't tell the public address from behind the NAT Jan 2, 2023 · This might reveal the turn server and the protocol (UDP and TCP endpoints might have different ports) and the credentials used to connect. The master list of display filter protocol fields can be found in the display filter reference. protocol data is malformed; protocol dissector is buggy; wrong protocol dissector used; It's difficult to say (in a general way) which is the real cause in a given scenario, without looking at the packet data and having some knowledge of the protocol (dissector) involved. malformed. RTP provides end-to-end network transport functions suitable for applications transmitting real-time data, such as audio, video or simulation data, over multicast or unicast network services. Wireshark In Wireshark press Shift+Ctrl+p to bring up the preferences window. Feb 14, 2012 · As i am new for using STUN protocol and i need to implement this in our code base. 11 dissector could crash. And then check in Wireshark for packets sent to that port. Wireshark allows you to play any codec supported by an installed plugin. Step 4: Identifying the IP Address To facilitate the identification of the desired IP address, use the search function of Wireshark. This page describes IP version 4, which is widely used. 3 Sending the STUN Binding Response. [Malformed Packet] Malformed packet means that the protocol dissector can’t dissect the contents of the packet any further. After the setting, most SMB packets are correctly decoded instead of TCP payload. If you encounter this scenario, then using a firewall rule to block the Teams IP subnets or ports from using the VPN should suffice. I'll look at reducing the number of TURN Channel dissectors to 1, to make this less confusing. This question is marked "community wiki". Older questions and answers from October 2017 and earlier can be found at osqa-ask. You can easily test WebRTC+TURN in isolation using this sample from the WebRTC project. The endpoint statistics of Wireshark will take the following endpoints into account: If you are looking for a feature other network tools call a hostlist, here is the right place to look. Protocol Jan 1, 2001 · Wireshark is a network packet analyzer. CaptureFilters. The protocol I'm seeing that I don't wish to is NBNS. cloudapp. Wireshark University US. and status of this protocol. Figure 4:Main Window of WireShark. I2C: (sometimes IIC) bi-directional two wires bus used in most of embeded system to transfer data. 8. I use wireshark to capture SMB packets with custom port (44555) due to port forwarding. 38, Wireshark starts applying a T. 12. Public Attributes: wmem_tree_t * Mar 6, 2024 · Wireshark creator Gerald Combs & core developer Roland Knall give an overview of the new Wireshark 4. 2 to 0. Then it sends out another STUN packet from local port y to gw port x. From RFC 5389 Section 15. First note that you're working with Wireshark's display filters, separate (and very different) from libpcap's capture filters. Wireshark now has a discord server! Join us to discuss all things packets and beyond! Ask and answer questions about Wireshark, protocols, and Wireshark development. Learn tips and tricks from Wireshark guru Chris Greer (Packet Pioneer). 5). Ethereal is decoding only the first interaction. From: bugzilla-daemon [Wireshark-bugs] [Bug 2837] STUN protocol decodes from Client to Server not recognised as STUN Jun 8, 2023 · Once the user answers the call, Wireshark will start displaying the captured data. History. stun. Look for information related to the STUN protocol in the list, and you’ll find the IP address of the user who received the call. The HTTP dissector could crash. The STUN binding response message MUST implement only . 3) Now, you will see your bandwidth usage in number of “packets”. STUNプロトコルは、アプリケーションがNATの存在と種類とを発見し、リモートホストへのUDP (User Datagram Protocol) 接続にNATが割り当てたグローバルIPアドレスとポート番号とを得ることを許す。STUNプロトコルが動作するには、インターネット上にSTUNサーバが存在 [Wireshark-bugs] [Bug 2837] New: STUN protocol decodes from Client to Server not recognised as STUN. From the given below image, you can see a reply from the host machine. Wireshark uses display filters for general packet filtering while viewing and for its ColoringRules. this include IPMB protocol. voice. 5: proto_classicstun = proto_register_protocol("Simple Traversal of UDP Through NAT", "CLASSICSTUN", "classicstun"); /* Required function calls to register the header fields and subtrees used */ This protocol was created to do that which SSL can't : to create a secure protocol under UDP. 4: Low-power wireless networking protocol intended for sensor networks. au file format. (Bug 1200 ) Versions affected: 0. RTP media packets are not normally encapsulated in STUN. Here is my Wireshark Profiles repository. However, this doesn't seem to work anymore. Protocol dependencies. Classicstun Wireshark for Steam IP. Sep 4, 2015 · Learn how to use Wireshark to track network activity, view specific frame, tcp, ip and http information, view specific packets being sent and received on the Jul 9, 2015 · ANNOUNCEMENT: Live Wireshark University & Allegro Packets online APAC Wireshark Training Session July 17th, 2024 | 10:00am-11:55am SGT (UTC+8) | Online The group that you select in the interface must match the one defined in the protocol-group. Hi - I'm sure this question has been asked and answered many times, but I can't find what I'm looking for. wireshark. Besides the STUN protocol using the filtering technique, the IP addresses’ Geo-Location plays an essential part. Official Protocol Standards" (STD 1) for the standardization state. To ensure Teams media traffic is routed via the Oct 10, 2023 · Wireshark is used to calculate the round-trip time on a path to see whether this is the cause of flawed Transmission Control Protocol (TCP) communications network performance. You can either filter as you capture with a capture filter, or in the display with a display filter. pipe. a web browser such as Mozilla) performs a HTTP request to a HTTP server (e. com. Dec 6, 2019 · If you want to learn more about WebRTC feel free to start our free email course here: https://webrtc. skypedata. Install tshark (e. SCOS is the EMEA Wireshark University Certified Training Partner. The most basic way to apply a filter is by typing it into the filter box at the top of the window and clicking Apply (or pressing Enter). Then you can use the protocol, destination IP address, port and IP Identification field to correllate the two. 1 and RTR-Site-2 200. our product sends out a STUN packet from local port x to gw port x. Now click Start. Dec 14, 2023 · community! I'm an intern in the field of load testing, and we are conducting reliability testing on a video conferencing system similar to Skype or Zoom using JMeter. RTP does not address resource reservation and does not guarantee quality-of-service for real-time services. Wireshark allows you to save decoded audio in . Jan 3, 2018 · 1. CVE-2007-0459. org. May 9, 2005 · The Hyper Text Transport Protocol is a text-based request-response client-server protocol. May 25, 2018 · For that protocol, the RTP and RTCP dissectors are registered as heuristic dissectors, but the RTP heuristic dissector is disabled by default; you have to enable it manually, by going to Analyze -> Enabled Protocols and enabling the "rtp_stun" dissector. However, there are still some packets Internet Protocol version 4 (IP) The Internet Protocol provides the network layer (layer 3) transport functionality in the InternetProtocolFamily. Wireshark's STUN/TURN dissector is, as indicated, dissecting the RTP packets as TURN packets. Click the "gather candidates" button on that page. 99. Probably 5060. If you would like permission to edit this wiki, please see the editing instructions page (tl;dr: send us a note with your GitLab account name or request access to the Wiki Editor group using the Gitlab feature). Important. Wireshark will begin capturing traffic and displaying it as a color coded list in the main window. The IP protocol is used to transfer packets from one IP-address to another. In the menu to the left, expand protocols. You could think of a network packet analyzer as a measuring device for examining what’s happening inside a network cable, just like an electrician uses a voltmeter for examining what’s happening inside an electric cable (but at a higher level, of course). Table 1 summarizes the malware counts associated respective STUN server usage. Apr 26, 2023 · In this video, we'll dive into the basics of the STUN protocol - what it is, how it works, and why it's important for real-time communication over the intern Jul 1, 2017 · If you want to filter to only see the HTTP protocol results of a wireshark capture, you need to add the following filter: http. Here is the console output when the server received an \"expected\" STUN Binding Request. This feature exists in Wireshark since version 0. Is it possible to filter stun packets by info column using this software? Thanks in advance. Click on the network interface you want to use to capture the data. 1 contributor. そして、トラブルシューティングを Nov 24, 2015 · 3. 1. Third-party media relays. These messages might appear in the packet list. In the case in the above question, that means setting the filter to: ip. Originally designed for VOIP apps. You will need to capture in front of the NAT device. 2. 1) Stop packet capturing from the interface. If the client knows it external (NATed) IP address, it can use that information in protocols like SIP and H. ventures/webrtc-basics-course and our hands on training ANNOUNCEMENT: Live Wireshark University & Allegro Packets online APAC Wireshark Training Session Protocol field name: _ws. The classicstun filter is supposed to show the ip of the computer you're pinging for voice chat via Steam. Using a capture filter you can limit the capture to only your "tracking protocol" by using something distinctive such as a host address or tcp\udp port or a protocol. Display Filter Reference: Session Traversal Utilities for NAT. Also the UDP port disection would be useful 3479-audio, 3480-video, 3481-desktop sharing/VBSS -> video based Screen Sharing Links / references / protocol specifications Wireshark is able to detect STUN messages and to dissect them for you, so you can use the ‘stun’ filter, or more sophisticated ones like ‘stun. 5. Check the Try to decode RTP outside of conversations checkbox. These ZIP files contain profiles that can be added to your Wireshark configuration to speed up troubleshooting and packet analysis in Wireshark. UDP: Typically DTLS uses UDP as its transport protocol. Public Attributes | List of all members _stun_conv_info_t Struct Reference. akadns. t-mobile. Jun 8, 2023 · Once the user answers the call, Wireshark will begin displaying the captured data. prd. For example, type “dns” and you’ll see only DNS packets. In the following articles we explain in detail what the STUN protocol is, its purpose, explain STUN I am using Wireshark . Unfortunately I cannot upload the result as a text file, I need to have 60 points (???) Apr 19, 2021 · Wireshark is the most well-known, usable and open-source. Session Traversal Utilities for NAT (STUN) is a protocol that serves. Run the provided script. 38 dissector to any UDP packet to/from the media Ethereal-dev: [Ethereal-dev] STUN protocol dissector. A. I can ping my internal DNS server. Voila! Here is a simplified version of how it works: The ICE layer of the LiveSwitch Client SDK gathers all types of candidates that it can. Next by Date: [Wireshark-bugs] [Bug 2376] UDP packet (KLive) wrongly dissected as " Redback Lawful Intercept" Previous by thread: [Wireshark-bugs] [Bug 2837] STUN protocol decodes from Client to Server not recognised as STUN; Next by thread: [Wireshark-bugs] [Bug 2838] New: Automatic selection of matching protocol is broken; Index(es): Date; Thread Playing VoIP calls. CVE-2007-0458. If it’s on a non-standard port (anything else than 3478) decode the protocol in Wireshark via a right-click as STUN Mar 29, 2023 · 1. It will use the same port as the RTP media packets. as a tool for other protocols in dealing with Network Address. 6. 2) Go to Statistics menu and click on I/O Graphs. 5 Back to Display Filter Reference Jun 14, 2017 · That’s where Wireshark’s filters come in. WebRTC is a free, open project that enables web Jan 2, 2018 · Display Filter Reference: Session Traversal Utilities for NAT. When you start typing, Wireshark will help you autocomplete your filter. If STUN, TURN, and TURNS services are available, all candidate types are gathered for both UDP and TCP, if at all possible, at all times. type. Jan 31, 2011 · 0. Shasi. See the security advisory for details and a workaround. 16. 223). The Wireshark network protocol analyzer. This was a great room - a bit of a challenge, but we are up for it. g. On a wired network, it will likely be eth0. 2: If the IP address family is IPv4, X-Address is computed by taking the mapped IP address in host byte order, XOR'ing it with the magic cookie, and converting the result to network byte order. ICMP: Internet Control Message Protocol (version 4): This is a protocol to report common errors and events in the IP, TCP and UDP protocols. In many cases, the operating system can be Feb 14, 2019 · 3. com I noticed some "Destination unreachable (Port unreachable)" from my computer to my internal DNS server. Dec 21, 2023 · In certain scenarios, often unrelated to Teams client configuration, media traffic still traverses the VPN tunnel even with the correct routes in place. 323 (and probably internally within the Hangout protocols) to Wireshark's STUN/TURN dissector is, as indicated, dissecting the RTP packets as TURN packets. Jul 22, 2010 · Using Wireshark, I captured the traffic for a call between me (private IP address 192. Step-1 is performed in ISAKMP phase 1 ( Main Mode ) through the messages one and two as shown below between RTR-Site1 172. , sudo apt install tshark on Linux or download Wireshark for macOS, which includes tshark). The DNS query response gives us the first clue that Microsoft’s usage of CDN networks has begun to creep into its UC (IC) platform. The basics and the syntax of the display filters are described in the User's Guide. 208. Jan 29, 2021 · WebRTC は P2P というイメージをお持ちの方が多いと思います。. 今回は P2P で繋げなかった場合に利用される TURN というプロトコルの話をします。. Prior to version 3. 4. 3 to 0. Since such SMB packets cannot be directly recognized, I then use Decode As function to set packets with tcp port 44555 as NBSS packets. I compared the three options and learned a bit about them. We are facing challenges simulating this traffic in Jan 2, 2018 · Display Filter Reference: Session Traversal Utilities for NAT. answered Dec 23, 2021 at 7:23. https://tryhackm \n \n \n. It’s called NAT-Discovery. Remove the default stun server and add the url and credentials for your own TURN server. Step-2: Detects if there is a NAT device along the path. If the request is valid, the endpoint MUST send a Simple Traversal of UDP through NAT (STUN) binding response message, as specified in [IETFDRAFT-STUN-02] section 8, with a subset of its attributes. Let's take a look at what filters we can use to solve this room quickly. If LinPhone doesn't use 5060 it might be that Wireshark doesn't recognize the SIP packets and you have tell Wireshark how to decode them, See this stackoverflow answer, but use 'Decode as SIP'. There can be various reasons: Sep 27, 2017 · Upon application start, Teams initially performs a DNS A record query for: pipe. NBNS serves much the same purpose as DNS does: translate human-readable names to IP addresses (e. Sep 30, 2020 · I'd like to analyse STUN attributes from MS teams. Teams media flows connectivity is implemented using standard IETF Interactive Connectivity Establishment (ICE) procedures. 15. DLINK_for_WireShark_Forum. 168. May 6, 2015 · wireshark-dissector. OpenSSL v0. TCP is used in various applications, including online surfing, data transmission, file transfer protocol, and many others. Please file a bug at the Wireshark Bugzilla , and attach a capture file containing the mis-dissected packets. May 3, 2016 · So data may be missing due to packet truncation, or there may be some protocol extension unknown to the dissector, or the actual protocol may be a different one than the dissector expects - e. Dec 28, 2021 · NAT Traversal performs two tasks: Step-1: Detects if both VPN Devices RTR-Site1 and RTR-Site2 support NAT-T. If you can’t find the data in burp start looking at Wireshark to identify the traffic. It's why this protocol is an adaptation of TLS 1. Sep 11, 2020 · 13730 691 115. 18 Back to Display Filter Reference Apr 25, 2015 · One Answer: 0. Packet List Messages. yahoo. NBNS runs atop UDP, on port 137, so a capture filter that captures only UDP traffic, and doesn't capture UDP traffic that's NBNS traffic, would be udp && !udp port 137. One should be streaming SRTP and the other RTP. ICMPv6: Internet Control Message Protocol (version 6): This is a protocol to report common errors and events in the IPv6, TCP and UDP protocols. Abstract. ping -l 1472 192. A display filter can either either filter out unwanted data, or Jul 3, 2017 · wireshark. They both are listed as RTP (in the protocol column) Though I get RTSP packets from the one camera, it seems to me the RTP packets are not encrypted at all. 4 Back to Display Filter Reference Jul 5, 2016 · TURN is a STUN extension so you will only see STUN packets in Wireshark. Are there any other viable ways to get someone's ip via Steam utilizing Wireshark or a similar program? Voice chat used to communicate using P2P, but Steam Apr 12, 2017 · In the captured packets, the use of the STUN protocol can be seen, and some answers of this protocol points to Google server, which could act as intermediary media server. A complete reference can be found in the expression section of the pcap-filter (7) manual page. 02/14/2019. Note: This archive is from the project's previous web site, ethereal. ) In Wireshark, the "Frame" section has various metadata about the Commit 3a5d0569 added support for different STUN protocol versions; a global preference allows the user to select the desired flavour. as soon as an SDP re-negotiation changes the codec from G. Jun 18, 2015 · 1. To easily identify the desired IP address, use the Wireshark search function. addr==192. We first see my IM client do a DNS resolution for Yahoo’s STUN service at ‘beta. 201 and http. There's also an IPv6 protocol page available. com’, yielding two IP addresses 68. This would either require a stronger TURN heuristic or a way to disable the TURN heuristic. Jan 2, 2018 · Display Filter Reference: Session Traversal Utilities for NAT. There is no well known UDP port for DTLS traffic. Distribution of this memo is unlimited. You could capture on the device with one Wireshark instance, then plug another pc with Wireshark in front of the NAT process. I installed Wire Shark on my computer and tried to open https://My. 0 to 4. According to MTU if the size of the payload is set to 1472 then frame size will become 1514 as explain above, let’s verify it from Wireshark. Click OK. Apr 17, 2023 · Find out which port LinPhone uses for SIP. This is the wiki site for the Wireshark network protocol analyzer. Learn cybersecurity with their experienced staff. proto == 'http' to http. With virtual multipoints, you should also create a stun protocol-group with different numbers for each of the virtual multipoints. 228. Oct 7, 2017 · Now we are sending the maximum size of payload using the following command. Protocol field name: stun Versions: 1. If the IP address family is IPv6, X-Address is computed by taking the mapped IP address in host byte order, XOR'ing it with NetBIOS Name Service (NBNS) This service is often called WINS on Windows systems. 142. The HTTP protocol header is text-based, where headers are written in text lines. 目的は単純で、本気で WebRTC を使う場合は繋がることが重要になります。. 233. Translator (NAT) traversal. 8b uses port 4433. I'm posting here to ask if the current version of Wireshark has any known bugs or caveats around the capture or display of the CLASSIC-STUN disscetor's XOR_MAPPED_ADDRESS value. 76 and 74. A network packet analyzer presents captured packet data in as much detail as possible. Follow-Ups: [Wireshark-bugs] [Bug 2837] STUN protocol decodes from Client to Server not recognised as STUN. STUN (Session Traversal Utilities for NAT; originally Simple Traversal of User Datagram Protocol (UDP) through Network Address Translators) is a standardized set of methods, including a network protocol, for traversal of network address translator (NAT) gateways in applications of real-time voice, video, messaging, and other interactive Jan 18, 2015 · STUN is Session Traversal Utilities for NAT. skype. 729 to T. 3) and a remote user in my own network (private IP address 192. Something is using it on your Windows, and I would scan for malware/viruses as those have been known to use STUN as an exploit: Feb 24, 2020 · A well positioned attacker could easily sniff the STUN password using Wireshark. The second task consists of updating transport address pair state values and discovering peer-derived candidates. . www. class==0x0010’ to see all Binding Responses. ISDN: Integrated Services Digital Network (digital There are three ways to write a custom dissector for Wireshark: C++; Lua; Wireshark Generic Dissector; Several years ago, I needed to write a dissector for a custom protocol my company uses. bs ox qb vm gr qj tw vb yz gc