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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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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56 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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2answers
196 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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4k 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
373 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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1answer
5k 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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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)?
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2answers
13k 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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1answer
139 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
1k 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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319 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
138 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 ...
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1answer
2k 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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1answer
584 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
743 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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1answer
963 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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1answer
3k 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
164 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
2k 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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159 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
1k 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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1answer
70 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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2answers
116 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
444 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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1k 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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3answers
6k 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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2k 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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233 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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1answer
112 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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2answers
5k 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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1k 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
1k 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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507 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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199 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
629 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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3answers
339 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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247 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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1answer
1k 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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1answer
507 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 ...
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737 views

What is the difference between UDP hole punching and STUN? [closed]

As the title says, what is the difference between UDP hole punching and STUN? Or is it the same?
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478 views

determine connections limit enforced by my ISP

I know my new ISP is enforcing a lot of different limitations. They refuse to say what are the limits. To determine bandwidth I can use sites like http://www.voiptest.org/ (BTW it shows me ~15% of ...
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266 views

Tunnelling TCP connection through NAT

My server is in my school's NAT and my desktop computer is in my home NAT. I want to SSH to my server from home. I normally used school's VPN, but recently for some reason I can't. So I'm looking for ...
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1answer
143 views

How to optimise a Motorola Wing 5.3 Access Point for UDP traffic

I have a motorola wing v 5.3 which I need to optmise for UDP traffic. I have some UDP packet loss and I think that if I change the AP configuration I would get a better result. Anyone has experience ...
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1answer
384 views

IP checksum offload

I recently updated to Windows 8 and get alot of invalid packet transfers. It says "Ip checksum offload?" (Wireshark) and most of my packets get lost. The checksum is 0x00. I also updated my NIC ...
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2answers
830 views

Puzzling TCP performance over 3G / UMTS

I'm using 3G as my primary internet connection, and TCP over this thing is getting more puzzling every day. For example: Downloading from kernel.org is crazy fast: $wget ...
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1answer
2k views

Connecting Android via wifi to Wifly RN-XV RN-171 using Access Point (soft AP) mode not working

I hope somebody has encountered this problem and knows how to fix it. I purchased a Roving Networks RN-XV module to communicate directly with an Android device. I thought it would be perfect because ...
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372 views

What would cause different rates of packet loss between client and server in UDP?

If I've implemented a reliable UDP file transfer protocol and I have a file that deliberately drops a percentage of packets when I transmit, why would it be more evident that transmission time ...
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464 views

Routers and NAT hole punching? [closed]

I'm trying to understand why UDP hole punching works. Given peers A, B behind a NAT router and Server with port 80 open. A sends a packet to Server from port 1234. This causes the router to open a ...
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3answers
1k views

Kill UDP port that has no process?

My VPN client sometimes can't bind to the UDP port (500) it uses. It seems to leave behind a "bind" to port 500 on a previous run, even though it has quit. The port is reported as "already in ...
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545 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 ...