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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DrayTek Vigor 2830 open port issue

We're using a Vigor2830 for routing VoIP/SIP traffic. One of the ports required to be open is 5090 for TCP/UDP. Going into the open ports section of the Vigor menu we have opened all the ports ...
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11 views

UDP fails horribly after waking from sleep (and maybe without sleep too)

We've got a PC running Windows 7 Home Premium that fails in a rather odd way after waking from sleep (and possibly other times as well, we haven't been keeping detailed records). The most obvious ...
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22 views

Why is there no UDP port forwarding in SSH?

I know SSH can forward TCP ports, not UDP. I'm not seeking help to circumvent this restriction (this subject is covered here). I'd like to know what is the reason SSH never got UDP forwarding ...
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32 views

Control excessive outbound traffic

Ubuntu server is sending outbound request excessively. I am not sure why this happening. Following is the output I am getting for tcpdump root@demotrt:~# tcpdump -n -n port 53 tcpdump: verbose ...
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9 views

Sending ihex file over UDP using sockets

I am working with IPv6 and UDP sockets using python-2.7. I am particularly focusing on IPv6 Multicasting ff02::1 where every Link-Local address device (with fe80::) responds to queries from a central ...
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26 views

Can two different applications bind the same port on a host if they use different protocols?

 my question is quite clear I think. If two applications use different transport layer protocols (e.g. TCP and UDP or something else) can they open the same port number? How does the OS do the ...
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13 views

UDP Forwarding redirection keeping source info in Linux

I would like to do an UDP Forwarding redirection of traffic in machine B, so UDP traffic from machine A would go to machine C. I have used iptables and that goes fine. The problem I have is that I'm ...
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1answer
40 views

How to ask router for bandwidth statistics?

I once heard that there is a UDP protocol for asking a router how much data has moved through it per minute, but a simple Google search did not help me identify it. What is the protocol called, and ...
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20 views

TCP and UDP do not work with firewall

I can not connect my TCP-Client to my TCP-Server. Here is my Code: http://stackoverflow.com/questions/35661591/tcp-server-does-not-work-with-firewall I have already opened my TCP-Port "8888" in the ...
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2answers
36 views

Why ICMP is different that TCP and UDP? [closed]

what is the difference between Internet Control Messaging Protocol over Transmission Control Protocol and User Datagram Protocol
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27 views

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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24 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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76 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
22 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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17 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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39 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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193 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
59 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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27 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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131 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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23 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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33 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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15 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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22 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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48 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
124 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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741 views

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

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 applications listening at the corresponding ...
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1answer
957 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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1answer
106 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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95 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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375 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
242 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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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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142 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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136 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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242 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
77 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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90 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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658 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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240 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
225 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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154 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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3k 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
373 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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3answers
757 views

How to use UDP hole punching for a SSH tunnel / session

I want to deploy a Raspberry Pi in my weekend cottage. The Raspberry Pi is there to log the temperatures and send them to a remote server which has a fixed ip, saves the data and displays it on a ...
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116 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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303 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
531 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 ...