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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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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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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278 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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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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211 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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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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121 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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372 views

How can I open a TCP/UDP connection on Linux?

I am looking for a simple command line tool to open TCP/UDP server/client on a desired port on a Linux machine. Are there any applications or commands that I can use to achieve this?
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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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536 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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72 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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80 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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519 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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365 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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417 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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143 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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1k views

NAT and UDP replies

Sanity check please. If I send UDP packets from Machine A 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 to pass ...
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315 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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171 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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282 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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438 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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263 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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160 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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567 views

TCP/UDP hole punching from and to the same NAT network

I was wondering if tcp/udp hole punching would still work when you are in the same network (behind a NAT), and what the packet's path would be. What happens when using hole punching on the same ...
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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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249 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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735 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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10k views

How to stream my media via vlc using udp streaming method?

I would like to know how to stream my media via vlc using udp streaming method?
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2k views

RTP input stream on VLC

I'm trying to play on VLC a RTP input stream coming from the port 9954, UDP socket. So, I launch VLC on the console with this command: vlc -vvv rtp://:@9954. VLC appears, but no media is played. The ...
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379 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 ...
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2answers
647 views

Wake On Lan will not work no matter what

I have been having the most frustrating time trying to get my desktop computer to wake up from a magic packet. The worst part is, I am almost 100% sure that I have had it working on this computer in ...
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769 views

Multiple connection attempts per minute on udp port 1024 - What might be the cause?

Here's a small sample from my firewall log: Sep 24 14:51:04 server Shorewall:net2fw:DROP: IN=eth0 OUT= MAC=44:87:fc:8a:f2:c3:00:04:ed:dd:e6:4a:08:00 SRC=213.5.110.105 DST=10.1.1.3 LEN=131 TOS=00 ...
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133 views

UDP client behaving differently for wifi router

I have a setup like, main router is connected to modem(ISP), I have connected one wifi router to main router, and another wifi router to above wifi router, so have 3 levels of routers. Now I connected ...
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DHCP: broadcast flag

I'm looking at some DHCP packets through wireshark. I notice that in the bootp section, there is a broadcast flag. However, the dest IP is 255.255.255.255. Isn't it enough to indicate that it's ...
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244 views

A port scanner or proxy server for testing UDP (or all other) protocols on particular (or all) ports

I have a problem GPS localizer (TK102), that is probably sending out data over UDP, but my server isn't receiving it (while it does from other clients, using UDP and this IP/port). I asked on ...
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493 views

How to transfer data between two networks efficiently

I would like to transfer files between two places over the internet. Right now I have a VPN and I am able to browse, download and transfer files. So my question is not really how to transfer the ...
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183 views

Log is full of “stealth mode connection attempt”s

My daily log is full of messages like: 8/25/12 8:27:01.385 PM Firewall: Stealth Mode connection attempt to UDP 192.168.1.101:40959 from 109.254.109.20:1098 where 192.168.1.101 is IP of my mac. ...
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901 views

How do I make netcat receive UDP packets from any host?

Is there a way to make netcat receive UDP packets from any ip:port? I don't want it to bind to a specific host as the first packet comes. I can consider alternatives, but they have to be bash ...
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173 views

Do asp.net windows server based server uses any udp packets [closed]

I am an indie browser mmorpg game developer. I am not using any streaming. Everything is http , web service or ftp. Now my question is does my server use any UDP packets? I just recently got ddos ...
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Can I get UDP Hole Punching with (any) VNC client to get around the local firewall/router?

I don't have access to the local internet router, so I'm unable to setup port forwarding on my lan connection. I'm just trying to find out if there is any way for me to get around my local router ...
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7answers
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Why is it bad to have open ports?

Here's something that has always baffled me. Why is it bad to have open ports on your computer? Assuming you don't have a virus on your computer or some other program listening to a port that may ...
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3answers
2k views

Good process specific packet sniffer / viewer?

I am looking for a good, free or not free, packet sniffer. The main feature I am looking for is an ability to watch a chosen process and view / read all of the data it is sending or receving. Also I ...
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1answer
704 views

Is there Windows utility to find out which process is sending UDP packets?

The problem is: Using Microsoft Network Monitor 3.4, I can know which process created a TCP connection, but Microsoft Network Monitor cannot report which process sends UDP packets. I'm a network ...
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2answers
1k views

how to forward and broadcast UDP packet from one network to another?

I want to forward udp packets broadcasted in one network to another. how can i do this ? I know we can put router in between and router can forward, but router can only unicast not broadcast.
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174 views

in wireshark how to know if packet was send to vpn or to internet?

Thanks to my previous question when vpn is connected intenet is not accessible I have configured VPN connection so I can use internet at the same time. Right now I write this post and I'm connected to ...
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How to determine which process sends UDP packets periodically to an IP address?

I tried looping with netstat and but the packets are small and not frequent so do not get caught (can still see them with tcpdump). Need to know which process sends those packets.
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Mounting an NFS share with udp or mntudp options

According to the documentation of NFS client on Mac OS X 10.7 user can specify following options: udp Use UDP transport protocol. and mntudp Force the mount protocol to use UDP transport, ...
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How to deliberately introduce a delay for incoming UDP packets

I want each packet (that match iptables rule) to be delayed by some fixed time interval. How to to this? Preudocode: iptables -A INPUT -p udp <more conditions> -j DELAY --delay 50000 # delay ...
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windows xp irregularly refuses to connect to one specific webserver

I think of myself as an advanced user but this problem is driving me batty. Windows XP (32bit Home) going through a WRT54G router, once or twice a day at completely different random times, refuses to ...
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987 views

Live video streaming over UDP?

What options are currently available for live streaming of video over UDP? Current solution uses libx264 and wowza media server, to serve up an rtmp stream. Unfortunately it's communicating over ...