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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.

Because UDP doesn't rely on handshaking to guarantee that packets arrive and in order it can be seen as an unreliable protocol, but for real time systems where acting on the data immediately is the most important consideration not having to wait for delayed packets is a distinct advantage.

UDP is just one communications protocol on the web. Others include:

  • Transmission Control Protocol (TCP)
  • Internet Control Message Protocol (ICMP)
  • Hypertext Transfer Protocol (HTTP)
  • Post Office Protocol (POP3)
  • File Transfer Protocol (FTP)
  • Internet Message Access Protocol (IMAP)

UDP on Wikipedia

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How to set specific broadcast IP address on Windows

Problem: I have a machine Sender, that sends packages to a certain IP address in a local network. I have also machines A, B, C, etc, connected to the same local network. I want these machines to listen to the packets from Sender inside, lets say, a…
Bersan
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DNSMASQ-TFTP failed sending file for PXE boot

2 month ago my PXE installation worked perfectly, now it can't send the file grubx64.efi to begin the PXE installation. juil. 08 08:03:05 install-server.my.domain dnsmasq[5913]: started, version 2.79 DNS disabled juil. 08 08:03:05…
Sommcrane
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DNS lookup failing even though tcpdump shows that nameserver has responded

DNS lookup on some of my EC2 instances have been failing intermittently. A reboot resolves the problem but it goes back to the same fail-state after a few hours (or after a few days), and remains in that state until a reboot happens When the failure…
SJH
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UDP broadcast with nc not received (Ubuntu)

I'm trying to understand UDP broadcasting, and running into some trouble. 1 - Running a server like this nc.traditional -l -u 10.0.0.253 -p 65001 2 - Sending stuff from the client like this - on the same machine - works: nc.traditional -u…
Kostya Vasilyev
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Achieving high DNS QPS throughput

I'm trying to find the maximum QPS (Query Per Second) of the DNS Resolver VM. We have our infrastructure hosted on Azure, having a VM (bind based) acting as a resolver querying Azure native DNS (168.63.129.16) as well as on-prem DNS. I'm not caching…
harshavmb
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Forward UDP ipv6 port in a VPS to UDP ipv4 port in another VPS

I have VPS let's say VPS X that doesn't have IPv4 but only has IPv6. and I have VPS let's say VPS Y that doesn't have IPv6 but only has IPv4. Since IPv4 is still common used today, and some device unable to access IPv6. I want use VPS Y network card…
Muhammad Ikhwan Perwira
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UDP Packets Lost (Ubuntu 18.04 into Windows 10)

I am trying to send UDP packets from Linux machine (Ubuntu 18.04 ) to a windows 10 machine. But the packets are not received at the Windows machine. I have already send UDP packets from Windows 10 to Linux machine and was successful. I have…
sandc
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Rolling updates of backend with udp server sockets

I have a backend system used for IOT devices which use UDP protocol for communications. And there are certain TCP (HTTP2) based APIs for mobile apps from the same backend. I am trying to build a rolling update feature to enable 0 downtime patching…
Gopinath
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rsyslog - Lower throughput when using omfwd with TCP vs UDP

TLDR; I'm getting significantly lower throughput when forwarding syslog messages with rsyslog on a Redhat server with 32 cores and 128Gi RAM to a remote server using TCP instead of UDP syslog in the omfwd action. How can I use TCP for forwarding…
Wood Techie
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iptables NAT REDIRECT

I have a server that is receiving syslog traffic. Many of my devices can only send to the default udp/514 port. My syslog server can't run on ports <1024 and is running on 5000. I have a nat PREROUTING REDIRECT on the system and it's working…
Dan Massameno
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Stopping UDP Attack

I am now getting support emails from OVH that there is unusual activity on my server. This is a simple server that I have RDP connections for students to access QuickBooks, Excel, and Word, and there is nothing else on the server, and I have group…
QuickBooksRus
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UDP to Serial port

I look for some solution for connect serial/UART port by UDP connection to another PC. Now I use socat and have connection , but with lost packages, and slow transfer. Can I use netcat for this, maybe it will get better solution? Can I get some…
Vitaly Rom
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Udp punchhole between two instances behind two different cloud NAT on GCP

Hi I'm trying to achieve UDP punchhole concept between two compute instances (on different networks with no public IP) behind two different cloud NATs for their respective networks. It seems that in logging I can see the connection being established…
Vinayak S
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How to identify source, destination ip using STUN and DTLS protocols?

enter image description here Given image i'm not able to identify which is source and destination ip address ( client or server). From STUN protocol 1st packet it's user request so i thought 131.202.240.150 is client ip address. From DTLS 5th packet…
David Roonie
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Docker macvlan drops UDP (DNS) traffic, TCP works

I'm trying to use macvlan to create a container that is a first-class citizen on my lan. I'm using a static IP (although I understand that using some 'tricks' it's possible to use DHCP as well). I understand its possible to do it with the host…
user123963
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