Questions tagged [udp]

UDP stands for User Datagram Protocol. With UDP applications can send messages (datagrams) to other hosts on a network without requiring prior communications to set up special transmission channels or data paths.

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Why is dig failing but tcpdump showing a response?

I have a situation where my dig command is failing with a timeout error when querying DNS over UDP, but when I check the packets with tcpdump it shows a valid response. I have a working server to ...
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Returning tcp/udp packets to sender

I'm using a Linux machine with WiFi hotspot to test the WiFi stack of an embedded device. For context, the embedded device is designed to send and receive encrypted packets to/from a remote server. To ...
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How to check if my network is blocking UDP traffic?

I have noticed that some applications on my phone are unable to connect when my phone is connected to my home WiFi, while they do work over 4G, even though my WiFi connection is fast and stable. I ...
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How do I intercept all udp packets and redirect them to a proxy?

System: win10 64bit . I want to positively intercept all UDP packets and then tunnel them through a proxy 127.0.0.1:29918, so they will all have to go through this proxy in order to reach the outside ...
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A datagram of 2020 bytes is being sent and the MTU is 1020 bytes. The headers have 20 bytes. How many fragments are created, and what is the offset?

A datagram with a total of 2020 bytes is being sent. The MTU is 1020 bytes. Assume the headers have 20 bytes. a) How many fragments are created and what are their sizes? b) What is the offset and the ...
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Issues with connecting to UDP Services?

I have an infuriating issue that I've been troubleshooting for some time now, has been happening for the last few weeks (just moved into my girlfriend's house and it has only happened there, no issues ...
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Why should one expect a ~30% drop in speed when using OpenVPN UDP with NordVPN? [closed]

https://support.nordvpn.com/Connectivity/1047408902/Speed-and-bandwidth.htm (mirror) mentions: If you are connected to the closest available server through OpenVPN UDP, you can expect around a 30% ...
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896 views

How to run wireguard over tcp with udptunnel?

I'd like to run wireguard over tcp. I wanted to use udptunnel for sending udp packets over tcp. However, when I run wireguard and then try to run udptunnel, the udptunnel fails with the following ...
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Data Flags....TC in Wireshark

Currently I am working on 802.11 Packet Extraction using scapy in python. I found strange character showing with the "IEEE 802.11 Data, Flags......TC" from Wireshark UDP packet. Can anyone ...
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How to port forward UDP though SSH

I have a setup where I'm forwarding port 5000 to a remote server with ssh -NR 5000:localhost:5000 root@server This only forwards TCP packets through the SSH tunnel, Due to new software which is picky ...
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How do I fix the magnet URI scheme?

I honestly can't remember how it happened but uTorrent is no longer associated with magnet links in Chrome. Every time I click on one, Chrome simply opens up a new window with an empty tab. I would ...
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Sending a UDP message stream - listener hanging after first receive

I'm attempting to use nc to send a stream of messages from one server to another using UDP. On the sending side, Centos 7.5, I'm doing the following: for s in $( seq 1 20 ) do echo "$(date +'%...
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Can ping a device but can not receive UDP Broadcast

I have a simple Setup which consists of a Windows PC-Ethernet Switch (10/100M)-Embedded Device. I can ping the Embedded Device, no problem at this stage. The Embedded device is UDP Broadcasting (SRC ...
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267 views

Can't receive UDP data unless Wireshark is running

We have a computer system (Win10) that receives a variety of UDP data from a remote host at various rates (2-50Hz). The remote system is provided by our customer. While we're waiting for the customer ...
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how to protect udp packets from packets loss?

when i tried to ping with mtr using udp pinging i gets packets loss from outside wan the result of (mtr 8.8.8.8 -s 576 -n -u): 5. 149.6.154.169 ...
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Impact of Enabling UDP Checksum (IPv4) on the System

AFAIK, UDP checksum is an optional feature on IPv4. I want to enable it on a gateway (IPv4), but I want to know if it has any negative impact on the system, e.g., increasing CPU utilization or ...
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Minimizing mpeg-ts package size produced by FFmpeg

Please, consider the following example, where FFmpeg is receiving a 48KHz-stereo-PCM audio input (by TCP) and sending it as a mpeg-ts audio stream to another computer (by UDP): ffmpeg -f s16le -ar ...
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What does it mean for a SOCKS5 proxy to have UDP enabled?

v2ray has options for enabling UDP for a socks5 server. What does this mean? How is it usable? How can I test the server to see if it is working correctly?
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Configure openvpn for ExpressVPN TCP ports

I want to use the openvpn client on my Ubuntu 20.10 to connect to ExpressVPN's VPN. Unfortunately I have to use the TCP ports, as the UDP ports are blocked. ExpressVPN's website only allows to ...
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how to get udp unicast to two hosts?

The two hosts need to have to same ip. My solution at the moment is a port mirror, but the problem is as mentioned the duplicate of the ip address, I think. I couldn't find a way to disable the IP-...
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Why is my wifi router delaying broadcast UDP packets?

I have a Python program running on my raspberry pi that opens a socket to receive broadcast packets (actually ArtNet lighting protocol). The pi uses its built-in wifi to connect to a D-link wireless ...
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394 views

What is this UDP traffic to 230.0.0.1? And how can I block it?

My VM is of IP 192.168.3.20 in the network of 192.168.3.0/24. While running iptraf command on my machine, I am getting the response as shown in the attached image. I can't understand what kind of ...
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AWS EC2 instance gets too much UDP loss/duplicates

When I send multiple UDP packets to EC2 instance, most packets are lost or duplicated. I expect that there would be some duplicates, but it's so massive compared to local network. For example, when 10 ...
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How to accurately throttle network interface with tc in linux

I am sending UDP packets from a Linux server over a dedicated network link (unswitched point-to-point 10GbE connection) to a piece of custom hardware. The hardware is an FPGA with a very limited ...
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UDP packets sent to wrong IP?

I have an IPTV box connected to my only router that assigned it a local IP 192.168.1.165. I tapped the LAN cable right next to tv box and recorded traffic in Wireshark. There I saw a remote IP from my ...
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ffmpeg add logo on livestreaming

i am using ffmpeg and i want to add a logo on livestreaming video i tryed the command ffmpeg -i myip:port/stream/channel/8cfdf5a5ae10f5b0ef2a70383065aa93?ticket=...
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First time setup of OpenVPN, cannot connect. Network is Unreachable. PiVPN

So i got an orange pi pc running armbian with pivpn/ openvpn with ethernet connected to my router. i have spent the last few days trying and researching on how to setup everything but i cannot get the ...
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How to set different TTLHOP for TCP ports

We want to set sensitive TCP/UDP Ports at low TTL/HOP Leaving other ttl/hop at 128 default data center = 3 Priv net = 8 Internet = 128 default Ssh 22 = 8 (internal hop max) Rdp 3389 = 8 Http 80 = 128 (...
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Constant receiving UDP packets from other local PC and firewall failed to block that specific IP address [duplicate]

Is it normal for a PC to keep sending out UDP packets to other local devices using random source ports? In my case, I'm using Wireshark to monitor my own Windows PC network and I found there is one IP ...
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How to route all Ethernet traffic to a Serial port on a Linux system?

How can I route all Ethernet traffic on a Linux system to a Serial port and the opposite? I want to convert from the first architecture to the second one, as shown in the picture: picture I monitored ...
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Routing from via remote bridge

Below is a diagram of my server and laptop, both inside the same LAN. On the left, I have a server with a bridge ip (.128). The server also allocate another ip (.118) from the router but only ...
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Sending audio data over UDP into terminal not working in macOS

I'm trying to send data over udp from gqrx/gnuradio (I think it's raw audio) into terminal and eventually into unity. In terminal I get no output at all, but in processing I can see some raw data ...
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284 views

Protocol on Wireshark says LLC

enter image description here A theoretical question may be. I have created UDP traffic across my network involving client and Server. When i ping the server and monitor the data using wireshark, it ...
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Chrome reports UDP port blocked but netcat can connect

I am using Chrome browser 84.0.4147.89 (64-bit) and when I run the Chrome Connectivity Diagnostics I get the following error log for UDP port 19302-19309. SUMMARY Test Name: Hangouts Connectivity ...
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420 views

WireGuard blocked - apparently a wider UDP issue

WireGuard is refusing to connect, I've tried running it on 2 different VPS providers (with my PC as the client) and it just doesn't work. There are some commonalities which I noticed: On both ...
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buffer deadlock prevented error from RTSP streaming over UDP

I have an issue to view RTSP streaming over UDP in the open VPN connection. Our project is to integrate 360 degree IP camera in unity system. And we want to get the UDP streaming rather than TCP to ...
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How to ensure mobile-PC discovery in LAN?

I am developing a game that uses a PC as a monitor and a mobile phone as a gesture detector. Both devices communicate using UDP on the same local network (mostly Wi-Fi). First, the PC creates a ...
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216 views

How does DHCP OFFER broadcast work?

I am trying to understand the concept of DHCP relay agents and was reading this article. In section 3.2, talking about DHCP OFFER, it mentions that the DHCP relay agent replaces the destination ip to ...
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What address type do DNS queries use?

I was reading this thread and it was mentioned that DNS servers use anycast address. I have also heard that there is something called Unicast DNS as well. So, my question is what type of addresses ...
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480 views

Is UDP full duplex or half duplex?

Can someone tell me if UDP is simplex/half duplex/full duplex? I read conflicting answers here and here. Would be great if someone can clarify this for me.
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How does DHCP handle multiple scopes in the same subnet

We are studying DHCP in our networking class and I have a Virtual Box in which I have set up 2 VMs - one of them is a Windows server and other is a Windows 10 workstation. I have added the DHCP ...
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638 views

Why are DHCP messages broadcast?

I am learning DHCP in my networking class and as a part of my research, I was watching the following video: https://www.youtube.com/watch?v=0UvLRVlPx6A So in the Wireshark capture in the above video ...
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103 views

Why do most application protocols have two ports assigned?

So I am trying to learn about the application layer in the OSI model and when I go to the IANA website, I notice that most of the well known protocols have same port assigned for TCP and UDP. For ...
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354 views

Displaying UDP Multicast Rawvideo Stream

I have a problem while trying to capture the raw video over UDP. In my setup, I stream the webcam with FFmpeg (command line) via UDP, on the client side I use Java OpenCV, the capture line; ...
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Cannot play video stream from FFMPEG to VLC

I'm trying to stream my local webcam using FFMPEG. For test purposes, I'm doing this locally and try to open the stream using VLC (3.0.8, Windows 10). This is how I stream from FFMPEG: ffmpeg -f ...
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629 views

SSH Tunnel + Socat UDP + Unicast + Multicast

I am trying to communicate from a machine LOCAL (sitting at home) with a scientific instrument (SCIENTIFIC, IP=192.168.1.109) which sits in a remote network along with a raspberry (SERVER). SCIENTIFIC ...
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/etc/nfs.conf equivalent for Debian/Ubuntu

What is the reason for /etc/nfs.conf not in Debian/Ubuntu? There are /etc/default/nfs-kernel-server and /etc/default/nfs-common, but they aren't the same. They're used by /usr/lib/systemd/scripts/nfs-...
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FFMPEG: How do I output appended log files for Audio (silencedetect) and Video (blackdetect) Monitoring of a UDP Stream (not an MP4 file)

I am outputting log files for both audio and video monitoring for a UDP stream showing silencedetect and blackdetect. I have working code for both however I can't seem to get grep to filter only ...
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42 views

using udpcast over the internet

can I use udpcast-receiver to send file from my office in one country to a different branch located in another country? if so what options should I use? I tried nc - netcat with tcp it works but with ...
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How to remotely tell a Mac to sleep without using SSH?

I am needing assistance in getting a Mac to go to sleep without the usage of SSH. Almost any other method is acceptable. Backstory: Product Salesman and Project Manger sold a thing without asking ...

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