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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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Port forwarding UDP10000

Sorry for my poor english... here is my network: Network I try to setting up a jitsi meet server behind my two Firewalls and the reverse proxy, but i meet a problem. I can access to video and sound through my lan, so the UDP10000 port is open on the…
ArnOCP
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OVH VPS as a reverse proxy - UDP DDOS attack causing invalid packets

I am using VPS from OVH as a reverse proxy to protect my dedicated server from DDOS attacks. OVH has very good DDOS protection. My dedicated server hasn't. Everything works good, I am attacking my VPS a lot via TCP attacks and OVH starts mitigating…
Radosław Klimaszewski
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SOCAT command for UDP relay using single port

I am using SOCAT linux command for relaying udp packets. Currently I am simulating using VMware. I used sudo socat -T 10 UDP4-LISTEN:132,reuseaddr,fork UDP4:192.168.11.130:130,bind=192.168.11.131:133 command that listens on port 132 and forward udp…
Nafiul Alam Fuji
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Returns of UDP packets are discarded

I use High avaibility pfSense 2.6.0 cluster and I strange behavior with UDP when use Discord voice channel. In fact, discord voice channel display "No route" and traffic analysis paquets traffics seem be discarded. The pfsense configuration is very…
user5525652
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iptable's ip forwarding results in weird behaviour

My target is simple : Build a high volume, fast, low latency soft switch using IP forwarding. I have a server test 'Server' and 2 test clients : 'Client1' & 'Client2'. 'Client1:c1' is sending udp packets to 'Server:s1' & 'Client2:c2' is sending udp…
Nafiul Alam Fuji
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iptables: can't drop incoming DNS responses containing a specific IP address

I want to drop incoming DNS responses that contain 10.10.34.35. How can I do that? I tried to it this way: iptables -I INPUT -m udp -p udp --sport 53 -m string --algo kmp --hex-string '|31 30 02 31 30 02 33 34 02 33 35|' -j DROP But it simply…
Masood Lapeh
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Too much download bandwidth on nginx process

I rent dedicated server from company and I noticed it is using too much download bandwidth constantly on nginx process even with low traffic on non peak hours. I checked with tcpdump and I saw those 05:59:41.415892 IP x.x.x.x.65524 >…
suuu
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Double Proxy: IPSec to Server1 then SSH to Server2

What I'm trying to achieve: (Clients)(Server 1)(Server 2) --> Free Internet How is that possible for both UDP and TCP traffics? What I've done: I ran this on Server1: ssh -N -D 1080 user@Server2:7999 I used gost…
Masood Lapeh
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How to test UDP echo using nping

I need to test performance of UDP echo server application. I use nping to generate traffic however nping always reports 100% packet loss no matter to which port the server returns the echo packets. Nping works OK when I run it in ICMP mode but this…
jackhab
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How AT commands can be used to know the TCP buffer status?

Atmega328p interfaced with ESP8266, vibration sensor. atmega reads vibration data from the sensor at a frequency of 10khz. Each value is sent over UDP using esp8266 UART-Wi-Fi passthrough mode to a raspberry pi sitting at a distance. The sample…
vishnu m c
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eBPF program appears to duplicate packets sometimes

I am trying to understand behaviour of eBPF/XDP under Linux. I have 2 machines connected by an isolated 100gE network. On one I run a udp sender application which is configured to send 10M packets of 1 byte each. On the other I run an eBPF/XDP…
Chris Ward
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How does linux / netfilter / iptables "know" if a packet is meant for itself for to be forwarded

I have setup an ubuntu box as a router manually , using iptables + NAT. But I was wondering, how does the "middle-router" know if the packet is meant for it or to be forwarded? I tested this scenario: SYN …
poiasd
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how to upload a udp stream to AWS

I have a stream that only has udp protocol and I need to upload it to my AWS cloud server. Is it possible to send udp to the server if I don't have the stream in the local network of the AWS server? If possible, how should I do it? Background: I…
Tobias Serpa
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traceroute shows stars but netcat reaches the port

I have several (virtual) machines with Centos 7 in the same subnet with several instances of my app running on each of them. I need to test how the apps can reach each other by UDP. I'm trying to access one machine from another one by tracerote. So…
Mike Siomkin
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How To Force User Agents To Use Later Available Version of HTTP?

A OpenLiteSpeed Web Server is running on AlmaLinux 8. HTTP/1.1, HTTP/2 and HTTP/3 QUIC are enabled. 80/tcp, 443/tcp and 443/udp ports are open publicly and permanently. The server is sending the below alt-svc header: h3=":443"; ma=2592000,…
user962126
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