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.

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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 ...
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47 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. ...
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22 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 ...
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13 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 ...
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3answers
792 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. ...
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37 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 ...
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20 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 ...
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11 views

UDP packet priorization simple howto

Is there a simple straightforward way to prioritize all UDP packets incoming on a specific interface? I have a UDP listener that receives information from external GPS devices through UDP, and when ...
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60 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 ...
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140 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 ...
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2answers
68 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 ...
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534 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 ...
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26 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)?
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130 views

Windows 8.1 cannot block UDP connection?

I installed a BT software, which requires both TCP and UDP inbound connection. But my router is very weak. If the UPD/Tx goes up over 100, the router will die. And Windows does not have a function to ...
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2answers
351 views

what is type of ICMP packets? TCP or UDP

ping packets is a type of ICMP packets.Is there any relation between ICMP with TCP.In other can we guaranty their arrival in the network I want to know ICMP packets in the network is tcp or udp or ...
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12 views

Ping works, TraceRt is intermittent [duplicate]

When contacting any somewhat remote IP outside my ISP's network, their edge router (hop 5 in my case) shows partial failures (perhaps 3-4 out of 5 attempts generate *'s), but PING traffic goes through ...
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42 views

How to determine mcast_if of process listening on UDP multicast address?

How to determine mcast_if of process listening on UDP multicast address? I know I can netstat -lnp to show what processes are listening on which addresses, but a process may have a mcast_if ethX. ...
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1answer
75 views

How to monitor TCP and UDP port changes

I am running software on a server that may be turning off some ports and need to find out what it is. I have the ports I need to check. I just need to find out what is turning them off. How can I ...
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3answers
163 views

Broadcast address in IPV4

I have a small network with the subnet mask 255.255.255.240 and the IP range is 192.168.2.1 - 192.168.2.12. From 192.168.2.1, I want to broadcast a packet. I don't want this packet to go anywhere ...
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1answer
93 views

Using and testing UDP data over the internet [duplicate]

I have a GSM modem that sends data via UDP (it appears) I have configured it to send all data to my public IP address over the internet but no data is arriving at my end so I need to troubleshoot. I ...
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1answer
58 views

Are all internet file downloads using FTP protocol?

I heard, FTP is used to transfer files over a network. Also heard that it uses TCP port 20 and 21. So TCP is connection oriented. We have acknowledgments. If the transmission is lost, we should be ...
2
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1answer
333 views

Linux SOCKS5 tunneling not working with udp traffic

I am using the command ssh -N -D 0.0.0.0:1080 localhost which works perfectly fine for my web browser, but when I try and tunnel a UDP traffic application it doesn't work. I thought that socks5 ...
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69 views

How to monitor the Remote IP Address to which UDP packets are sent in a particular process?

I am able to do this with Network Traffic Viewer or Smart Sniff (both from Nirsoft), but on my friends machine (Windows XP), when running this application the internet is just cut off, like the entire ...
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146 views

Netcat one-time message

I'm trying to use Netcat to debug a UDP listen server that I'm writing, and I'm surprised by the behaviour: $ echo -n Hello World | nc -v -u -6 localhost 12201 - Connection to localhost 12201 port ...
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1answer
296 views

“udp relay” via openssh socks proxy

I'm trying to run a UDP based multiplayer game (dota 2) via the following chain dota2 (OS X)-> proxycap -> ssh tunnel -> home machine (OS X) -> internet The home machine is running the ...
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1answer
236 views

How does a proxy know where to forward the requests to?

When a proxy receives a connection how does the proxy know where to forward the request to? For example in Java we can set a system property for proxy. So we set the IP of the proxy and the request is ...
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361 views

Are UDP packets firewall proof?

I have been testing this "bittorent sync" software (a peer to peer application) as an experiment. I decided to block the application using the Windows firewall on the computer that is running the ...
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911 views

What range of UDP ports may rtsp use, to configure a firewall?

To allow incoming rtsp streams, I must open incoming TCP port 554. I must also open a range of UDP ports. 6970 through 6999, says http://comments.gmane.org/gmane.comp.security.shorewall/660 . At ...
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1answer
107 views

Wake-On-LAN and Access Control List with Mac over Internet

I am researching the best way to wake my computer through a firewall over the internet remotely (the computer to be woken is a Mac). Through external research, I have seen that I should be able to ...
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1answer
855 views

netcat udp address already in use

I am trying get a response from the server by using the command echo 'my message' | nc -l -u 127.0.0.1 2947 But I get nc:Address already in use. for a response. How do find the reason for this ...
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106 views

Send data from file to local UDP port

I've got an application, A, that listens on a user-defined UDP port for a specific message that normally comes from another application, B. Application B has a tool that allows recording these ...
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1answer
618 views

Limit UDP outbound traffic to loopback (localhost) instead of eth0

Atm i'm testing it on Ubuntu Server at VMware Workstation + Windows 7 local host with bridged connection. Later this has to go to live server. I have VLC streaming video file on Ubuntu with cvlc ...
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46 views

TCP vs UDP Error-Checking

I've bounced upon two articles that describe in-depth on how TCP and UDP connections work. However there is some kind of inconsistency. Where one article tells me that UDP does no Error-Checking at ...
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79 views

Port forwarding beginner

I have been trying to set up port forwarding for the past 48 hours and I can't quite get it. I have used online port scanners to see what ports are open and they are saying none, not even the port I ...
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1answer
242 views

DNS: can't dig 8.8.8.8 directly

me@ubuntu:# dig @8.8.8.8 google.com ; <<>> DiG 9.9.2-P2 <<>> @8.8.8.8 google.com ; (1 server found) ;; global options: +cmd ;; connection timed out; no servers could be ...
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566 views

FFmpeg/avconv and UDP - connect listener after sender?

I'm trying to troubleshoot a port binding issue in avconv/FFmpeg. I have two test commands; one which sends an audio stream over UDP: avconv -i test.wav ...
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2answers
1k views

How to detect if network is dropping UDP packets?

I'm got a video streaming application that runs fine in my office but fails miserably at the customer location. The symptom is that every couple of seconds, I stop receiving UDP packets for 2 seconds, ...
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1k views

vlc part of desktop streaming to <host>:<port>

With VLC, I wish to stream a portion of the desktop and send it to another host on my local area network. The capture seems to work, I see a correct portion of the desktop into the VLC server, but ...
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99 views

Is sending syslog events over udp secure?

I'm considering using a service from papertrailapp.com (other similar services are loggly and splunk), where you configure your syslog to echo events to it over udp. It involves adding this entry to ...
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69 views

My laptop can't find a device that is connected to a my router but my other laptop can find it

I have this device that uses port 80000 and UDP. It came with a program that communicates with it. However, my laptop (laptop A) can't find that device using the program. So I tested the program to my ...
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1k views

Why is my UDP so slow?

I'm using Iperf on two VMs and when using TCP I find the performance is as follows: notroot@ubuntu:~$ iperf -s ------------------------------------------------------------ Server listening on ...
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615 views

How to direct a UDP Packet through a vps tunnel?

How to direct a UDP Packet through a VPN Tunnel over a WAN? Have been trying to set up a instant messenger service though the office network and it dose not have UDP flooding or UDP broadcasting. ...
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1answer
424 views

UDP packet and firewall

I notice when I send udp packets from computer A to computer B, B can receive the upd packets correctly but if I send udp packets from computer B to computer A the udp packets are not received A and ...
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315 views

Dropbox LAN sync - hint for an IP address

In my work network UDP broadcast networks are isolated between the WiFi and wired channels, so LAN sync discovery does not work. Is there a way to explicitly tell Dropbox to try a specific IP address ...
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130 views

UDP NAT punching for linksys wrt54g

I could not explain the strange NAT behavior, hope someone could help: I have a linksys wrt54g router at home. Client sends UDP keep alive packet from 192.168.1.20:16688 (nat outside public IP/port ...
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1answer
387 views

ffmpeg udp audio livestream

Having trouble getting the following command to stream audio through udp, is there a parameter missing? ffmpeg -f alsa -ac 1 -i hw:1 -ar 44100 -f mpegts udp://10.255.255.255:10000?pkt_size=1316 The ...
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192 views

UDP checksum inconsistency between sender and receiver

I want to write a program to generate udp checksum. to validate my progra, I need some real data. I send a udp packet from one machine to another machine, the packet can be correctly received by the ...
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163 views

Artificial network delay tcp/udp (bigger ping) for defined application? (windows)

I have a game where people can easy detect who i am looking at my ping, i want to make my ping highter. How can i set network delay for all network connections for defined application?
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434 views

How to get rid of UDP checksum error messages in virtual console?

Whenever I am streaming a video in the web browser, while connected to my school LAN via ethernet, and switch to the virtual console (ctrl-alt-f1) on Ubuntu, I get an error that looks like the ...
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242 views

How to wrap an UDP connection to improve resistance agains packet loss?

Suppose there is UDP connection that does not expect much packet loss. Are there already tools that allow wrapping a UDP connection to gain more reliability at expence of bandwidth and overhead, for ...