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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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Redirect incoming UDP traffic to a local ip adress (iptables?)

tcpdump works as expected on my machine. tcpdump -i enx00e04c04009e -Uw - | tcpdump -en -r - vlan 201 17:52:51.447340 04:01:30:00:00:16 > 03:00:03:00:04:00, ethertype 802.1Q (0x8100), length 66: vlan 201, p 0, ethertype IPv4 (0x0800),…
Aleksandarf
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Error in udp reverse proxy with nginx stream failed (90: Message too long)

I want to proxy UDP traffic with nginx. nginx doesn't complain about the configuration. The client connects halfway (it says it can reach the end server), but the connection gets stuck and eventually times out. nginx version: nginx/1.18.0…
shunya
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IP fragments are not reassembled due to packet loss in Linux

I have been working with a device that sends heavy TCP/IP traffic. I'm trying to capture those packets in my Linux machine (Ubuntu 22.04.2 LTS) with Python programming language. But, most of the time the sent packets are not received correctly from…
mustaphos
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iPerf3 UDP TX/RX bytes mismatch but no loss

I am not able to interpret the following iPerf3 results. Client: iperf3 -c SERVER -u -R -b 350M Connecting to host SERVER, port 5201 Reverse mode, remote host SERVER is sending [ 5] local CLIENT port 47128 connected to SERVER port 5201 [ ID]…
kingofworms
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Interpret Iperf3 results for bidirectional UDP Test

I am trying to make sense of the raw logs of an iperf3 UDP bidIrectional test. Here are the iperf3 client logs: [ ID][Role] Interval Transfer Bitrate Jitter Lost/Total Datagrams [ 5][TX-C] 0.00-1.00 sec 1.04 GBytes …
LM10
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Rocky Linux 8 Blocking SIP traffic

I am having trouble with Rocky Linux blocking SIP traffic from an external LAN. If I send a SIP message from external LAN, it reaches the server but the message doesnt get passed to the application. If I send a SIP message from local LAN, it reaches…
FredBloggs78
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using putty and socat to run rust server behind firewalls

i want to run a publicly accessible Rust server on a windows machine behind some routers and firewalls. the idea is tunneling the local server ports to a public machine where they are accessable: rust server on windows behind firewalls <- putty…
weiss100
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Is there a way to exclude a network interface from being bound via INADDR_ANY?

In network programming, it's common to pass INADDR_ANY (or IN6ADDR_ANY) as part of the second argument to bind(), telling the networking stack that you want the socket to receive connections/traffic from any network interface that the machine…
Jeremy Friesner
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Kubernetes - NodePort with persistent connections

I am running a multi-node cluster of UDP game servers that need to be accessible to the player on a single domain name and port, i.e. example.com:19132. The game runs in a way that requires a series of UDP packets to be sent consistently to the same…
Ilhan Ates
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tcp syn is blocked, cant make a connection

so this is my current setup of openvpn+stunnel user>>internal-server-A(as stunnel client)>>main-out-of-country-server(running openvpn and stunnel as server) it worked fine in a restricted country for a while. but now tcp and udp connection from…
IMIEEET
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SIP Websocket to UDP proxy server

There is an ATS provider with SIP phones. It provides phones via UDP, as I understand, giving sip server, login and password for each internal call-line. I want to write a site with browser calls ability. As I understood, searching the web, I can't…
Ngdgvcb
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How can I print the payload received with ncat?

I'm creating an UDP server with the following command: ncat -ulk -p 3333 -c "echo asd" -vv It does receive connections and answers to them correctly, but it doesn't print the UDP payload that comes in the client's message. The client I'm using is…
Dan
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Netcat UDP server is not sending a response

I'm trying to get OpenBSD netcat to listen to UDP connections on a particular port (3333) and interface (10.42.0.1) and send a fixed response. To achieve this I do: echo "asd" | nc -k -u -l -p 3333 -s 10.42.0.1 -v And then I send a message by…
Dan
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Piping data from ethernet to serial and back to ethernet doesn't reach destination

CONCEPT VISUALIZED I'm trying to establish a bidirectional communication where ethernet UDP packets enter a linux system (suppose a Raspberry pi) from eth0 interface and piped into the UART hardware of the system, then read by the second linux…
zanglorion
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Forward UDP broadcasts to another IP

I receive UDP broadcast packets on wlan0 on my Raspberry Pi which I'd like to forward to my desktop for analysis via eth0. I'm running a modified WiFi firmware on a raspberrypi which sends UDP packets on wlan0. I can capture them with tcpdump on the…
Aravind Voggu
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