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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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Can a connection between "cone NAT with port restriction" and "symmetric NAT" be established without a third-party?

Directly it's impossible, right? Using an intermediate server isn’t an option because I have a requirement that says that a solution has to exchange lots of data and also be fast. Although, creating a simple utility, if required, that’d run on both…
mixtouku311
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UDP-Packets seem to get lost in IPsec tunnel from Strongswan to AWS cloud - connection works with Openswan

Use case: IOT-device connected through AWS cloud The IOT-device is behind a router that sends all traffic through aws cloud. The IOT-server can not be configured and thus is not part of the AWS cloud For configuration, the IOT-device needs to be…
DoRe
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OpenVPN does not connect outside network

We have a small office setup, currently due to pandemic employees need to work remotely therefore we are tying to configure OpenVPN so they can access internal applications. Using following tutorial I'm able to connect openvpn from inside the office…
DAKSH
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UDP NAT is not working

I have, among others, the following iptables NAT rules on the machine with IP addresses 192.168.1.71 and a.b.c.d, where a.b.c.d represents a public IP address: iptables -t nat -A PREROUTING -p udp --dport 20001 -j DNAT --to-destination…
asinix
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How to check the udp port is accessible in an Ubuntu machine which is protected by a firewall

We were trying to install "Big blue button" in an Ubuntu server with a firewall. For installation, we need these UDP ports ("16384-32768") should be opened in the firewall. But we don't know whether the udp ports are opened or not in the firewall.…
aks
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Decoding TCP packets as RTP in Wireshark

I'm troubleshooting a WebRTC video calling problem in my app and i'm using Wireshark. One end of my video call is a web app running in my browser window and the other end is a Unity based app on an Android device. This is built with WebRTC. In…
Salbrox
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how to proritize UDP port in tc

I have this TC code sudo tc qdisc add dev eth0 root handle 1: prio sudo tc filter add dev eth0 protocol ip parent 1: prio 1 u32 match ip dport xxxx 0xffff flowid 1:1 where XXXX is the port number. I know that this is for TCP. how can I achieve this…
striker69
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iptables: setting specific rules to IP aliases

We run several game servers all using one port with the use of IP Aliasing, the game servers bind to a specific aliased IP that belongs to the main dedicated server. I've setup netplan already and it worked, however I wasn't able to setup…
CortexPE
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OVH server DDOS attack protection

I purchased the server on ovh.com. (not gaming, regular) For 3 days now I’ve been trying to set up protection against DDOS flood. Nothing comes out. Support responds once a day and does not give an intelligent answer. Therefore, I appeal to you. How…
Xhonor
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Windows Vista DHCP bug, arp authorize, isc dhcp, workaround

I am trying to find a workaround for the Windows Vista Force Broadcast bug with ISC DHCP and a Cisco Router. The problem is not windows vista trying to obtain an IP address from us that works fine (with or without the flag enabled). THe problem is…
jinanwow
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TCP NAT forwarding works, UDP doesnt

I am using an Ubuntu Computer as a Router. It has a network connected locally on eth0 and is also connected to the internet with another interface and inside of an OpenVPN. I set up NAT port forwarding, so I can reach a few of the devices in the…
Vatril
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iptables matching pattern followed by 4 random values followed by another pattern

I'm trying to create a iptables rule that matches the following pattern in this UDP packet: 0x0000: 0000 030a 0000 0000 0000 0000 0000 0800 ................ 0x0010: 4500 0027 5d30 0000 6c11 232a 5164 585d E..']0..l.#*QdX] 0x0020: c0a8 6402 fe25…
Tryhard3r
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Udp session Netflow

How netflow defines the end of the udp session. That is, as I understand, there must be some timeout in the absence of requests from the dynamic port with the passage of time after which a new session for this port is formed. If yes, how it is…
egor
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Any protocol used by TRACEROUTE ? ICMP or UDP

Any protocol used by TRACEROUTE : ICMP or UDP or IP ? Or use them all : Encapsulation ?
Karim Michel
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heartbeat timeout error in tsunami deamon

I am trying to transfer a large file from server A to server B using tsunami. I am getting following error: Heartbeat timeout of 15 seconds reached, terminating transfer. And here are details: Receiving server: tsunami> get…
shantanuo
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