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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What is a simple STUN test I can perform from a Windows machine?

I want to test whether someone else's Windows machine can access a public STUN service using UDP and receive a response on its network, which I expect is behind a NAT and firewall. I do not have ...
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11 views

UDP port 9987 wont open on my firewall

I have a zywall-usg-200 and i have tried to open ports, i managed to open two TCP ports but the UDP port 9987 fails, cant connect to it. Does anyone have the same problem? Or is it just my firewall
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52 views

UDP “connections” rejection

I'm managing (edit: is hosted by VPS hoster) small machine for couple of game servers and website server (apache) together with some friends. Problem is firewall sometimes drops UDP packets. The ...
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1answer
18 views

Read UDP packages created by another computer

Laptop 1 Laptop2 192.168.1.103 192.168.1.120 Ubuntu Windows 8 ? <-- Matlab: UDP I use MATLAB software on my windows and I ask it to generate real ...
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9 views

NTP not getting through even to DMZ

My home router seems to be blocking UDP 123. sudo ntpdate -u time.apple.com works as expected, but sudo ntpdate time.apple.com I get: "no server suitable for synchronization found" I can get a ...
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25 views

Why do UDP Packets stop being sent if TTL Expire message received?

I have a program that sends UDP packets to devices as part of a task. If during this task, any of the targeted IP addresses causes a TTL Expired packet to be received, the program can no longer get ...
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70 views

Understanding “cat proc/net/udp”

# cat /proc/net/udp | egrep "sl|3ADBFE0A" sl local_address rem_address st tx_queue rx_queue tr tm->when retrnsmt uid timeout inode ref pointer drops 16: 3ADBFE0A:007B ...
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1answer
49 views

What is the reason for speed jumps in this Wifi transmission?

In this picture: The X axis is time slots of 5 seconds each and the Y axis is the number of 1KiB packets transmitted in that slot. The blue graph shows the actual number of transmitted packets ...
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21 views

Capture only UDP traffic that cannot be identified as another protocol

I have applied the udp filter in order to just capture UDP traffic, as described in Wireshark Wiki: Show only the UDP based traffic: udp However, this does not only show UDP traffic. It shows ...
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85 views

How to stream video by using UDP VLC player?

I am trying to stream the video and this is what I did. start C:\Progra~2\VideoLAN\VLC\vlc udp://@:60000 start C:\Progra~2\VideoLAN\VLC\vlc.exe C:\Progra~2\VideoLAN\VLC\FullDuplexRadio.3gp ...
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18 views

Looping back network traffic on the same machine

I have some 3rd party software that expects UDP traffic to/from other machines on the same UDP port. I want two instances to run on the same machine and talk to each other. I'm running it in ...
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28 views

unknown local address in TCPView

I'm looking at connections in TCPView, and I'm seeing "red5" in the "local address" column. This doesn't appear to match any computers on my local network, the names of which I have seen from time to ...
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13 views

Multiple UDP servers at same port, only locally?

Someone sends a UDP packet over the internet to a router public IP and port. Can this packet reach all the PCs of the LAN (using broadcast?) if they are listening on the port for UDP ?
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16 views

simulation gets disconnected from adhoc network when working with UPD blocks

I'm working with MATLAB simulink and trying to send data using UDP block from a model running on external mode (on a quad-copter which runs on linux ) to a model running in normal mode on my computer ...
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33 views

Broadcasting with socat via UDP, timeouts (maybe package lost?)

I want to setup a small broadcaster. I capture the stream from a program via UDP and broadcast it through the network (from IP *2 to *32, because just maximum 32 devices are connected). If I give ...
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1answer
97 views

Why ping/latency lower in-game than command prompt?

Is it weird that when i tested my ping to a specific gaming server on cmd, and it showed a constant and stable 42 ms (never below that), and When i played on that server in the game, it showed my ping ...
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1answer
435 views

Is ICMP port unreachable error generated by both TCP and UDP? [closed]

I have doubt ! Problem is A program on machine X attempts to open a UDP connection to port 5376 on a machine Y, and a TCP connection to port 8632 on machine Z. However, there are no ...
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1answer
531 views

OpenVPN working with TCP not with UDP

I have successfully set up an OpenVPN server on Debian (raspberry pi model b+). With the protocol set to TCP it works exactly as desired (internet routed through VPN, access to local network ...
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93 views

Detect RIPv1 via NMAP

Due to the recent increase of reflection attacks noted by Akamais security teams using original RIP(classful, depreciated) I'm interested to see if some of the CPE running within a network segment ...
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6 views

Route only on output chain?

I have two machines A and B. I want to send iperf traffic from A to B, but first have it route through a userspace program on A. I did this with a tunneling device: therefore, I used the command ip ...
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79 views

iptables block access to all ports except 53 (tcp,udp) from one IP address

how can i block all ports from one IP address except the port 53 TCP,UDP? example: ip 192.168.0.15 access only port 53 (udp,tcp). thank you.
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289 views

How to tunnel UDP traffic over Tor?

I know that Tor does not support UDP for now . But I came upon certain application Onion Cat .But I don't know if it work or not . Is there any other procedure ? Is that even possible ? Please guide ...
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1answer
185 views

ISP Issues - TCP Out-of-Order

Accessing any webpage (basically any TCP connection), results in multiple retries before and long loading times before it loads a page with missing elements (reload might fix it). Google Chrome throws ...
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3answers
798 views

Is it possible to process millions of datagrams per second with Windows?

I am investigating if I can implement an HPC app on Windows that receives small UDP multicast datagrams (mostly 100-400 Bytes) at a high rate, using a dozen or up to maybe 200 multicast groups (i.e. ...
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116 views

UDP over Internet

I have a small problem: I want to program a simple Apllication that sends a small word (in this case: "Hello") to a server. This Server should display it via cout. This is just a project to learn how ...
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117 views

UDP traffic through OpenVPN tunnel

I want to tunnel UDP traffic (Video) through OpenVPN between two clients. I am able to ping both the clients but unable to transmit video through the tunnel to the Client B.
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188 views

Can't connect to udp tracker (Rtorrent)

So I just got rtorrent, fixed my settings, but it still won't connect to udp no matter which torrent i use, udp is enabled and every settings seems fine. Still I can't connect! Reply if you need some ...
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1answer
61 views

Unable to see broadcast packets with tcpdump

I am launching an application which broadcasts udp packets. I also have a simple python script to confirm that these packets are being broadcast: sock = socket.socket(socket.AF_INET, ...
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80 views

UDP traceroute delay?

We are seeing timeout packages when running traceroute command between two Linux systems on a private network. However, we do not see such symptoms using TCP or ICMP over traceroute. This is a private ...
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179 views

sshuttle using tproxy error requires recvmsg function

I'm using sshuttle from this repo https://github.com/seanzxx/sshuttle because im using OSX Yosemite. (Original version from apenwarr not working with OSX Yosemite). it's working fine with this ...
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1answer
537 views

Why filtering on udp port in TCPDUMP gives only fragmented IP frames

I've a device capturing traffic with Tcpdump filtering on "upd dst port" then it creates a pcap file to be read in wireshark. what I obtain from running: tcpdump udp dst port 5201 -qUns 0 -i wlan0 ...
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193 views

What is the primary function of the transport layer in the Internet protocol networking code [closed]

I am not sure if I have answered this question right, so would appreciate it if someone could correct me. The question is: What is the primary function of the transport layer in the Internet protocol ...
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1answer
208 views

COD4 Linux game server doesn't send UDP packets as response to broadcast

I am setting up a bunch of Game servers for a medium sized LAN tournament using CentOS 6 and the various Linux binaries used for the game servers. With COD4 the servers did not show up in the server ...
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130 views

Forward all TCP and UDP connections over VPN

I have the following setup: OS: Ubuntu v13 Software: PPTP NIC 1 (eth1) IP: 10.2.95.207/24 Gateway: 10.2.95.1 (this is the network I want to connect to) NIC 2 (eth2) IP: 7.82.176.254/8 (the network ...
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50 views

Do I need to join a multicast group to send a packet or joining is just for listening?

I am confused here. Can anyone just send a packet to a multicast address and port? Where does the multicast group come into play here? Do I also need to send to a group? Can someone explain that to ...
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2answers
2k 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 ...
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1answer
308 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 ...
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108 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 ...
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216 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 ...
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48 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 ...
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2answers
444 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 ...
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1answer
7k 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?
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293 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 ...
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796 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 ...
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1answer
353 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 ...
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1answer
189 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 ...
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21 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?
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624 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 ...
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147 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 ...
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150 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 ...