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.

learn more… | top users | synonyms

-1
votes
1answer
13 views

Testing a Firewall against outgoing UDP ports

I'm trying to test which outgoing ports are allowed through a firewall. At the moment I can do this for TCP by port scanning portquiz.net (which is a server with all TCP ports open) from inside ...
0
votes
0answers
22 views

utorrent connectivity: Router drops packets

I have some problems downloading via uTorrent 3.4.2 on Win 7 x64. Symptoms: DHT is either Waiting to log in or Nodes (0), under Trackers its status is Waiting for announce... For any torrent, all ...
1
vote
1answer
3k views

UDP blocked by Windows XP Firewall when sending to local machine

I work for a software development company but the issue doesn't seem to be programming-related. Here is my setup: Windows XP Professional with Service Pack 3, all updated Program that sends UDP ...
1
vote
0answers
23 views

OpenVPN sans port forwarding on unfriendly networks

I have a problem. I'm about to move onto campus right in the middle of the semester. For a student, I have a complicated network setup where all of my systems are reliant on NAS and all of them VPN ...
1
vote
2answers
496 views

Force DNS resolution to use TCP

My Comcast internet connection has been giving problems in DNS resolution, and I am guessing the reason is a probably broken or limited UDP. I am currently working around it by tunneling over TCP ...
5
votes
2answers
8k views

For what does ssh use UDP?

Wile doing research I noticed that SSH both uses TCP and UDP. I completely understand the use of TCP, but UDP seems a bit strange. Why would I use an "unreliable" transport protocol with minimal ...
1
vote
0answers
30 views

Home router config to allow for UDP broadcast

I have a homegrown piece of software that "listens" to UDP traffic at 255.255.255.255:5010. It works just great on my home network, but does not work on other people's networks. I think that my ...
0
votes
0answers
34 views

How to create a wireless-to-ethernet router?

I have a Debian machine, which I want to turn into a router. It will connect via wireless to a access-point, where it will get an IP. To its ethernet port, other machines will be connected. It will ...
0
votes
2answers
67 views

UDP socket flushed. What are the limitations? When it blocks?

I plan to send high amount of data through UDP (video streaming), and I thought in a system that requires to detect when an interface has reached maximum upload bandwith. I know that when I flush the ...
0
votes
1answer
219 views

Play UDP stream in VLC?

I receive an UDP video stream of which I know both the IP adresses and the incoming and outgoing ports of both computers. How can I plat his in vlc? udp:@:1234 Doesnt work for me. How to fix this?
1
vote
1answer
74 views

How to experience UDP hole punching using Ncat under Linux?

I'd like to see UDP hole punching in action. I tested it under Linux, using Ncat. Here's what I tried: Open port 1234/UDP on host A and port 12345/UDP on host B's firewall (I'm still behind NAT, but ...
1
vote
1answer
145 views

What is the difference between UDP and HTTP torrent trackers?

In the context of bittorrent what's the difference between http and udp trackers? HTTP is an application layer protocol and UDP is a transport layer protocol so the concepts seem non-overlapping. I ...
0
votes
1answer
84 views

Tunnelling UDP Traffic Through OpenVPN

Referring to this answer I'm trying to route UDP streaming through an available OpenVPN tunnel. On the VPN client machine, I've access to a UDP stream over an IP (udp://1.2.3.4:5555) which I want to ...
35
votes
4answers
35k views

UDP traffic through SSH tunnel

The title pretty much sums it up. I would like to send UDP traffic through a SSH tunnel. Specifically, I need to be able to send UDP packets through the tunnel and have the server be able to send ...
1
vote
1answer
91 views

Emulate console by sending data on one UDP port, and receive text from another

I'm trying to establish a “console-like” connection with a National Instruments cRIO-FRC. It broadcasts its console output onto 255.255.255.255, UDP port 6666. I can listen to it with: socat ...
0
votes
1answer
17 views

Which criteria is used by the linux kernel to pick udp source ports?

They are all of course greater than 1024, but can we narrow this range a bit more? Via wireshark the lowest I've seen is 30XXX. Does the kernel specify it's criteria somewhere?
0
votes
3answers
170 views

Can a VMWare player virtual machine receive udp packages?

I have a virtual machine running in VMWare player v6. The network type is NAT. An application in my virtual machine sends UDP packages to a server in the network of the host machine and needs to ...
0
votes
1answer
78 views

WPA blocks UDP broadcast

I use a convenient program called KDE Connect to interface a Linux/KDE computer with an Android device. It uses UDP broadcast. And it worked fine when my wifi was not encrypted. I recently had to ...
5
votes
1answer
4k views

WiFi UDP unicast vs. multicast speed

From what I have gathered UDP multicast / broadcast over WiFi will not yield the speed as one would have thought. What about UDP unicast over WiFi? Can anyone confirm that the latter will have a ...
1
vote
1answer
54 views

UDP port scanning

UDP is connectionless, so I can't expect a response packet, necessarily. If the port is closed, I might get an ICMP error message, but if the firewall could silently drop the ICMP packet How could I ...
0
votes
2answers
36 views

VNC (or RDP) server using outbound connection only

How do I set up a VNC server that connects to an intermediary server to start an outbound communication, that can be used by a VNC client. This way the port forwarding doesn't need to be set up, and ...
4
votes
2answers
5k views

Does it matter what UDP port a WOL signal is sent to?

i have seen many WOL instances use port 7 and many use port 9, does it matter? Isn't it just looking for a WOL packet at layer 2 or ethernet?
1
vote
0answers
163 views

Re-stream (forward) UDP-Live-Video-Stream (using winsock) reduce video quality?

So, I used ffmpeg to stream the live webcam using UDP protocol to port 1111 : ffmpeg -f dshow -i video="Lenovo EasyCamera" -f mpegts udp://localhost:1111 When I played it directly by ffplay from ...
0
votes
2answers
109 views

Is the Transport Layer (e.g. UDP, TCP) handled by the Operating System usually? [closed]

I'm really new to networking and am struggling to understand this. I know the Transport Layer in the Internet Protocol Suite (at least the UDP and TCP protocols) contains the source and destination ...
0
votes
1answer
25 views

NAT and UDP replies by default

If I send UDP packets from Machine A with local port M behind a NAT to Machine B's port N, where Machine B is outside the NAT (elsewhere on the Internet), can I reasonably expect that NAT would pass ...
0
votes
1answer
397 views

How to sync two looping videos with mplayer and upd?

I am trying to sync two instances of mplayer with -upd-master and -udp-slave, and notice that the slave staggers for about a second when the master begins the loop anew. I am running debian 7.1 with ...
0
votes
2answers
142 views

What does a network packet consists of?

I know basic networking but I am not very good at it. Now I am calculating how many packets will be lost if I use UDP over IPv4. I can assume that the protocol overhead for data sent via UDP over IPv4 ...
1
vote
1answer
63 views

14 bytes preceeding the UDP packet, what is their purpose? Linux

I am analysing packets being sent from an MT4000 telemetry device. I have set up a listener in the terminal(Linux) and set to display the packets being received in hex. So far the packet incoming ...
0
votes
0answers
298 views

Streaming screen over LAN with VLC using RTP

I am trying to stream the screen (video and audio) from a Windows PC to a Linux one (Raspberry Pi), using VLC. I have tried emitting the screen through RTP (I want to do unicast), and then in the ...
0
votes
0answers
724 views

udp client sending ICMP “port unreachable” when receiveing messages from the server

(Note: I moved this question from StackOverflow, because it's to be considered off-topic there, better fits here, and still unsolved) I have a udp client using luasocket, basically doing this (with a ...
0
votes
2answers
2k views

My Mac keeps broadcasting UDP packets to 255.255.255.255:2008

The source port changes rapidly, from 49xxx to 6xxxx. I tried to use lsof -i udp, and see there's process named mDNSRespo which holds a lot of udp sockets. However, none of these sockets' ports are of ...
1
vote
1answer
732 views

How to listen to all ports (udp and tcp) or make them all appear open in Debian

I got an external Debian server. The problem is that my university campus doesn't allow connections to go outside when the port is different than TCP port 22, 80, 443, or UDP port 123. I tested them ...
-2
votes
1answer
125 views

Public wifi on public bus blocks all udp packets [closed]

Our public bus service gives us free WiFi but all UDP packets are blocked because I couldn't play online games that uses the udp protocol or make voip calls on my android phone. I ran a test on the ...
-1
votes
2answers
136 views

Is there a simple audio player that can be remote controlled with UDP or TCP commands? [closed]

Is there a simple audio player that can be remote controlled with UDP or TCP commands? The control needed is very simple: Stop Play Pause Volume up Volume down Next Track Previous Track
1
vote
1answer
236 views

TCP vs UDP. Sending data on a closed port

I try to understand differences between TCP and UDP packet on the error-checking. I know that UDP packets are connectionless and doesn't care that the packet will arrive the destination safely. And ...
1
vote
0answers
68 views

Is it possible to edit TCP and UDP packets?

Is it possible to edit the UDP and TCP packets a program sends? For example, we have a program that sends some information to its server. But we don't want to send some information that might be ...
0
votes
0answers
236 views

UDP port binding to loopback interface

I've been trying to play a video game in multiplayer, but after trying a lot of time, I begun to realize there was some problem with my loopback interface (Windows 7) I have UPnP activated in my ...
0
votes
3answers
67 views

Changing the ports a program uses

This question might not even make sense. I have a very limited understanding of how networking protocols work. My phrasing of these questions might be very poor. My school has a firewall enabled. ...
0
votes
2answers
473 views

UDP Flood to Host in the firewall logs

When the router's firewall logs shows as follows UDP Flood to Host PRIVATE_LAN_CLIENT_IP, PORT ->> EXTERNAL_PUBLIC_IP, PORT (from WAN Outbound). Will those packets be routed to the private lan ...
0
votes
0answers
190 views

How to use netperf on specific NIC port?

I have two servers, SERVER and CLIENT and each server has its own onboard 1 GbE ports, and its own NIC with a 10 GbE port. SERVER and CLIENT are interconnected on both a 1 GbE switch (administrative ...
0
votes
2answers
3k views

OpenVPN client behind corporate firewall

I cannot connect from the corporate network at work to my OpenVPN server. However, with client and server settings untouched, connecting from other networks works. I can only assume that this is due ...
1
vote
0answers
476 views

What is blocking incoming packets to port 67?

I have a DSP connected to a Windows 7 laptop by Ethernet. The laptop has all firewalls disabled (I’ve even tried stopping the Windows firewall service and DHCP). The DSP is sending well-formed BOOTP ...
0
votes
1answer
99 views

DNS Resolver for Windows over TCP

I know that DNS uses UDP with Port 53 for DNS queries. However, at my place sometimes UDP requests are blocked and DNS fails. I know that there is protocol for DNS over TCP and many public DNS servers ...
4
votes
3answers
1k views

How to force a process transmit over UDP instead of TCP?

I 'm running an ffserver process on a Linux machine, in order to achieve video streaming via ffmpeg. However, there is a delay on video streaming. On ffserver configuration file I define Port 8090. ...
0
votes
0answers
52 views

UDP causing problems with other connections

I have implemented a file transfer program on Windows 64-bit platform using winsock API. I am using a 1Gbps connection. When I transfer files using TCP protocol, I am getting only 320 Mbps. when I ...
4
votes
2answers
6k views

Netcat stops listening for UDP traffic

I am using netcat on some Linux machines (see this other question), but seeing some unexpected behavior. Unlike the guide in the accepted answer, I am not using UDP tunneling to do DNS queries. I ...
0
votes
2answers
160 views

Can using UDP and OpenVPN lead to file corruption?

I know with TCP that it always checks your files to ensure nothing got fragmented or lost or destroyed. So if I use UDP for OpenVPN to download files or access an internal network, does that mean I ...
0
votes
2answers
264 views

UDP communication through proxy

I have following scenario: PC B must be capable of full TCP/UPD connectivity, so I'm testing scenario with typical FPS game. ProxyCap is proxifier software, that can connect to outside world ...
-1
votes
1answer
34 views

How does an ADSL modem tell which local client to associate with each response from a server?

Does an ADSL modem generate a random string for each request I make and when response comes it directs it to my computer (but not to my phone)?
6
votes
2answers
10k views

How to generate UDP packet

I want to generate UDP packet to test a program, something equivalent to using telnet to test TCP port (Can telnet generate UDP packet?) How can I do this?