Unity Receive Udp Packet

UDP connection returning false. com/public/qlqub/q15. UDP properties: unreliable, packet-switched, packet data, no connection overhead, application-level protocols exchange information immediately, two-way communication. Thanks for reading! And if you want to get in touch, I'd love to hear from you: chris. I know the IP-adres of this device and the port number it is sending the packets to. Socket Send and Receive [C#] This example shows how to send and receive data via TCP/IP using Socket in. UDP is connectionless. Home › Forums › Support › Simple Broadcast and Receive of Raw Bytes using UDP Tagged: Broadcast , UDP , Unmanaged This topic contains 7 replies, has 2 voices, and was last updated by Anonymous 5 years, 1 month ago. I am new to Unity. UnicastUdpSocket failed to set receive buffer size to 1428 packets (2096304 bytes); actual size is 89 packets (131071 bytes). com’s UDP Buffer Sizing page, which includes commands for reporting the number of dropped UDP packets for several operating systems. 6, i can't receive UDP packets correctly. The packets contain sequence numbers. Strangely, the receiving application often receives a packet with an OLD sequence number that takes the place of the expected packet, always somewhere in the middle of the receive. These are the cases i want to timeout, because what happens right now both in Unity 4 and 5 is that the entire Unity thread just becomes unresponsive. If none of these options work for you it's possible to write a custom network backend for Dissonance - any system which can send unreliable packets (e. A Unity ID allows you to buy and/or subscribe to Unity products and services, shop in the Asset Store and participate in the Unity community. Each message to a number of different key, subcontracting, subcontracting to a packet sequence number, the sender sends the sub gradually, over a period of time to check whether the received packet response, did not receive a response packet, to send. Use the block for stateless and connectionless data transmission. A Simple Multi-threaded TCP/UDP Server and Client V2. Some ISP's seem to block really tiny UDP packets. William, I've now applied all updates up to 8. I have captured the packet send and receive from this application. Hey guys, So I am using Unity to create a virtual environment, where I am moving an object around the space. UE4 AnswerHub. Loopback, 0); // Setup background UDP listener thread. Receiving packets - udp_rcv() udp_rcv() is the handler for all UDP packets from the IP layer. This download was checked by our antivirus and was rated as safe. 1629462811 packet receive errors 179722143 packets sent This is showing the total number of UDP packets received and sent, plus two extra metrics. com/public/qlqub/q15. IPPROTO_UDP says that it will use the UDP protocol (the standard transport layer protocol for datagrams in IP networks). If you choose UDP as the transport protocol for your cluster service, you need to configure it in the UDP sub-element in the JGroups Config element. The receiving performance is down compared to a single threaded program. All devices are connected to the same Wi-fi network. I belive StackTask() function only give the status of the packet receive and send. UDP itself is not a reliable protocol like TCP and therefore users work to find the highest data rate they can achieve before experiencing significant packet loss. First let me say this is my first post. No other values are valid. It's the Android version of the client. c,sockets,udp. 170, the provider is Microsoft, but should svchost be sending / receiving?. First let me say this is my first post. This article aims to give the readers a quick grasp of raw sockets idea, its design internals, and its successfull implemenatation BSD Raw Sockets API. On receiving a udp packet from a device (SNMP trap to be specific), source IP address is replaced by docker gateway Ip. Instructor Lisa Bock begins by reviewing normal traffic, comparing TCP, a connection-oriented protocol, with UDP, a lightweight connectionless protocol. With each sample, the block output emits the contents of a single UDP packet as a data vector. I know the IP-adres of this device and the port number it is sending the packets to. We want to use the Floppy Jukebox as a synthesizer for a MIDI keyboard. Send end receive UDP in unity3d. This is an implementation of the User Datagram Protocol described in RFC 768. Two other Scapy functions related to sending and receiving packets are the srloop() and srploop(). This parameter is the UDP port the DatagramSocket is to receive UDP packets on. They are truncated after the first byte (i receive only 1 byte packets). With UDP, computer applications can send messages, in this case referred to as datagrams, to other hosts on an Internet Protocol (IP) network. There are methods Socket. That being said, I'll try to make my question clear. So, let's strip this away, and now we're down to TCP and UDP. In Unity I have an object with a script attached and the script is designed to simply listen and record data coming in off of the UDP packets. 1629462811 packet receive errors 179722143 packets sent This is showing the total number of UDP packets received and sent, plus two extra metrics. But our test program was an external exe (Blaster. I've been trying to move to the new networking stack but I'm facing a difficulty. * This was created to work with the program UDP_Minimum_Talker. In effect, to get something reliable you'll need to implement something similar to TCP on top of UDP, and you might want to consider using TCP instead. This blog is the third in a series about our upcoming networking technology known internally as UNET. - There are three modes the application can run in, Send/Receive, Send only or Receive only. UDP: Stands for "User Datagram Protocol. Description. Instructor Lisa Bock begins by reviewing normal traffic, comparing TCP, a connection-oriented protocol, with UDP, a lightweight connectionless protocol. Hi Eskimo, Thank you very much for the quick response! I know packets may be lost, but when I previously used the same method, on the same device, in obj-c (iOS 7 I think), it worked fine. So I assumed that random UDP packet loss isn't the issue (if I lose a few packets out of many, it's not a big threat), but I currently l. It can be used for both commercial and personal use. Packet Sender is an open source utility to allow sending and receiving TCP and UDP packets. EventSystem and server are running on separate threads. The alternative would be an independent send for each desired destination. The only difference is in the coding. TCP also guarantees delivery of data as well as that packets will be delivered in the same sequence in which they were sent. They are truncated after the first byte (i receive only 1 byte packets). Unity UdpClient and UWP DatagramSocket for receiving UDP broadcasts. Since the port 500 packet that you are receiving is a duplicate of the previous packet it is definitely not a reply packet for the port 4500 packet. Sending UDP packets • When you receive a packet, the ip and port number of the sender are set in the DatagramPacket. Send UDP packet in C#. With UDP, computer applications can send messages, in this case referred to as datagrams, to other hosts on an Internet Protocol (IP) network. Well, I stumped our local unity expert also, but we did a debug session in my office and after about an hour, we found out it is not the code. Send method sends data from your buffer to a connected Socket. simple udp implementation (send/read via mono/c#) To start receiving news from Unity. I am currently using recvfrom() to read the packets from the socket, but it appears to be too slow to keep up with the rate I am receiving data. If the server were to send an acknowledgement immediately after receiving each packet from the client there would be significant overhead (the acknowledgement is a 32 or 64 bit integer, which is very small compared to the whole size of the packet which also contains the IP and the UDP header). I have captured the packet send and receive from this application. /** * A simple datagram client * Shows how to send and receive UDP packets in Java. As mentioned earlier, TCP and UDP ports are not the same, and thus do not overlap. The reason is explained below and has nothing to do with the Qt implementation on Android:. c,sockets,udp. connected:receive([size]) unconnected:receive([size]) Receives a datagram from the UDP object. Use the block for stateless and connectionless data transmission. The QUdpSocket class can be used to send and receive UDP datagrams. In that, I was able to send and receive a UDP packet of message size 65507 bytes, which means the packet size was 65507 + 20 (IP Header) + 8 (UDP Header) = 65535. Introduction. The problem is that if I send the number 5 I want to get the number 5 but I get different values (I think it is similar to bits but I don`t know). Then how i know the StackTask() found the UDP packet or other and how can i fetch data from that one. Two Objects for send and receiving UDP-Packets. Unlike TCP, UDP doesn't establish a connection before sending data, it just sends. When trying to diagnose an occurrence of dropped packets this can be particularly helpful in determining if packets were dropped at the operating system level due to a socket buffer overflow. The receiving performance is down compared to a single threaded program. Send end receive UDP in unity3d. HTC Explorer does not receive packets at all ( 0% ) - now I understand what's the problem. That would be required for every packet (since connection-less). net framework, and not unique to unity. "UDP Connection"! Small high frequency packets (20-30 /sec) ! Packet based comm results in new challenges ! Packet loss ! Especially if client asks for higher rate then their connection can handle ! Inherent latency ! Bandwidth + Latency => Lag => Player frustration ! Varies from client to client. 4 --data-length 1550 UDP mode, to port 2090 at address, with a packet length of 1550 bytes. The UDP specifications allows different vendor software on each server/route to vary the maximum number of bytes by a small amount. Sending UDP packets with VBA I have an Excel / VBA Sports Event Management application for registration, heat draws, scoring etc. Now my wireless has the following issues: Packets sent but no receive! Problem aquireing IP address. Hope it's useful to somebody. A server can immediately listen for messages once it has a socket. We want to use the Floppy Jukebox as a synthesizer for a MIDI keyboard. Separate the words with spaces (cat dog) to search cat,dog or both. This makes UDP ideal for real-time services such as VoIP. UDP generates and checks checksums to catch transmission errors. The UDP Receive block has two output ports: Data and Size. Hey, I've got a very simple bit of code that listens for UDP packets and uses them to turn the LED attached to digital pin 7 on or off. These programs are absolutely basic, trying to get the concept and understand how it works. The process of sending and receiving. 5 6000 test Which part of the configuration of OS X should I check?. Sending and Receiving String via UDP. /** * A simple datagram client * Shows how to send and receive UDP packets in Java. Unity3D) submitted 3 years ago by Fellshadow This is my first foray into networking, and I've googled around, attempting to learn how to broadcast and receive using UDP. If the frame's payload size itself is maximum of 1472 bytes (as per my textbook), how can the packet size of IP be greater than that which here is 65535? I used sender code as. View Homework Help - hw3. Processing Forum Recent Topics. Re: Unity Client stops receiving UDP after a while Post by HumanPoweredGames » Tue Jul 17, 2012 3:35 pm I thought I had replied to this a while back, but I don't see the post so I'm re-replying. I have observed that B4A does not receive UDP packet unless and until sent sub is not executed. Hi Eskimo, Thank you very much for the quick response! I know packets may be lost, but when I previously used the same method, on the same device, in obj-c (iOS 7 I think), it worked fine. The protocol that X-Plane uses to send/receive the data is UDP, hence the UDP in the title above. The Size output emits the current size of the data in the UDP buffer as uint16 value. I appreciate if anyone can help. UDPSender and dsp. Can anyone confirm that a UDP multicast receive is working for them. I have to unplug the modem and disconnect the coaxial cable for 30 seconds to get it to work again if I dont it the connection doesnt return. Sending UDP packets from the command line Posted on March 15, 2012 by moy Although is pretty easy to write a perl/python script to send UDP data, I wanted to be able to send a UDP message from the command line to test some code quickly. “UDP Connection”! Small high frequency packets (20-30 /sec) ! Packet based comm results in new challenges ! Packet loss ! Especially if client asks for higher rate then their connection can handle ! Inherent latency ! Bandwidth + Latency => Lag => Player frustration ! Varies from client to client. Notice: Undefined index: HTTP_REFERER in /home/forge/shigerukawai. User Datagram Protocol is a simpler message-based connectionless protocol. Some application-level protocols use UDP because it is more lightweight than TCP. String newData = "New String. User Datagram Protocol (UDP, RFC 768) •Same service (or lack of) as IP –connectionless, no state maintained –unreliable, no notification of arrival (datagram may have been discarded, duplicated, or delivered out of order) –no flow control (source may transmit faster than destination is able to receive) •UDP adds to IP. • A port is open on a machine if there is a running (server) process on the machine and the port is assigned to this process. Occasionally games allow queuing up and distributing events (rather than packets themselves) to avoid everything happening at once after a lag spike, but this is not something you do with UDP, as the packets do not generally "buffer" like on TCP. In Ubuntu, that's nc. I appreciate if anyone can help. port == 14550 or similar as the filtering command to only show that traffic. Since the port 500 packet that you are receiving is a duplicate of the previous packet it is definitely not a reply packet for the port 4500 packet. The srploop() does the same thing except for… you guessed it, L2 packets!. - Mon Apr 25, 2016 3:51 pm #46163 The transmitter reads a GPS and puts a muticast packet into the air with the lat and long after the receiver get several packets ( it varies ) it will crash and reset I have the latest core 2. The last statement in the previous code snippet receives a datagram from the socket (the information received from the client gets copied into the packet). Use the block for stateless and connectionless data transmission. (GPL, BSD/Linux/Solaris/Mac OSX/Win32) Network Expect is a framework that allows to easily build tools that can interact with network traffic. You setup the listener using an AsyncCallback. 170, the provider is Microsoft, but should svchost be sending / receiving?. Then I am using a script to send OSC UDP messages out which contain the coordinates of that object as it moves. Though it may be possible to send a packet from sockets other than 0x9092, such sockets cannot receive UDP datagram destined to a well known socket 0x9092. Another optimization is that OVN enables UDP checksums on Geneve tunnels by default. Learn how to use Wireshark, the powerful protocol analysis tool, to deal with packet loss and recovery, so you can keep traffic moving. User Datagram Protocol (UDP, RFC 768) •Same service (or lack of) as IP –connectionless, no state maintained –unreliable, no notification of arrival (datagram may have been discarded, duplicated, or delivered out of order) –no flow control (source may transmit faster than destination is able to receive) •UDP adds to IP. This is what I tried, but I guess there’s something wrong with this, cuz it does not receive any packet. The received packet will contain correctly the data of the first waiting packet plus so many null bytes as data is available. But it receives well from the same device and also sends the packets well. This is from the nmap package, or is sometimes packaged as nping separately. I also considered just accumulating all the packet data, and parsing using the HTTP header information, but there has to be a better way No, there doesn't. The video sender uses OpenCV to read video frames from a webcam, and sends the data over UPD to the video receiver. Receive messages on the server. By default Netcat uses the TCP protocol for its communications, but it can also UDP using the -u option. However, if you do not call connect() on the UDP socket, you can use sendto() and recvfrom() to send/receive packets to/from multiple destinations. The second line shows UDP packets that were sent to a port that doesn't have a listening socket, then the third line shows packets that were dropped by the kernel. TCP properties: reliable, connection-oriented, byte-stream, connection established before application-level protocols exchange information, two-way communication. This is the method I use for receiving ALL data from the server. Receiveing data by UDP don't work. The host-based flow control expects periodic update packets from the device. When this happens, the client re-requests the packet from the server until the whole packet is complete and is identical to its original. Even if I use a raw UDP socket, the kernel is still dropping broadcast packets whose source address don't match any interface's subnet. The video sender uses OpenCV to read video frames from a webcam, and sends the data over UPD to the video receiver. Реализация UDP на C# using System; using System. For example, if you have a packet stream that is:. The UDP Send and Receive blocks use the 'localhost' for transferring data across two different ports. Rate this: C++ lost UDP packets that in real they are delayed. RPS is the same concept as RSS, but done in software. An UDP client can send "n" number of distinct packets to an UDP server and it could also receive "n" number of distinct packets as replies from the UDP server. How to prevent Engine to load a library. Then setup packet > forwarding on the port you are sending udp packets to: > > redir add udp:: > > example: > > redir add udp:4444:4444 > > This will then have the emulator "listen" on your local machine's port > 4444 for UDP packets, and forward those to the emulator's ETH adapter > on port 4444 (which can be changed to whatever you need). There is no issue making individual calls between online users. UDP Test Tool 3. But gameplay has been degraded in both cases. I wanted to send this in intervalls so UDP would be my way to go. The buffer size may be increased for high-volume connections, or may be decreased to limit the possible. Hope it's useful to somebody. Where could I add something to free the memory? Thanks. Consult your OS documentation regarding increasing the maximum socket buffer size. More than 40 million people use GitHub to discover, fork, and contribute to over 100 million projects. In this example, you will use your Ethernet Shield and your Arduino to send and receive text strings via the UDP protocol (Universal Datagram Packet). On Parallel UDP-Based Transport Control over Dedicated Connections. UDP connection returning false. 5 6000 test Which part of the configuration of OS X should I check?. If you choose UDP as the transport protocol for your cluster service, you need to configure it in the UDP sub-element in the JGroups Config element. For this reason, the UDP protocol is typically used for streaming media. It means a UDP server just catches incoming packets from any and many hosts without establishing a reliable pipe kind of connection. Author: Rama () www. sampleTcpUdpServer2. UDP like TCP is a protocol for packet transfer from 1 host to another, but has some important differences. UDP packets are used to send data from one computer to another over a network or from one application to another within a single computer. barkeley_udp_server receive packet irregularly Hello all I am using PIC32MZ EF starter kit. How to C# Socket programming C# simplifies the network programming through its namespaces like System. The srloop() will send the L3 packet and continue to resend the packet after each response is received. I wrote a small app that sends UDP packets from the Android device. The problem is, you'll have to piece together what's going back and forth based on the contents of the packet. You send a message off into the ether, you might listen a period of time for a response, and the payloads are small enough to fit in a packet. Send and Receive UDP String. In theory of course you can send any packet to the server but it doesn't mean it will accept it. 5b) The client uses its key to encrypt the packet+CRC and send it to the server, including one packet with the PlayFab auth token. The Transport Layer can use two protocols: UDP for generic communications, and WebSockets for WebGLA JavaScript API that renders 2D and 3D graphics in a web browser. So you'll have to handle packets getting lost and packets arriving out of order. Calculate the number of bytes successfully transmitted. In the green filter field, enter the below pattern to filter the traffic by the selected UDP socket port: udp. If the UDP object is connected, only datagrams coming from the peer are accepted. That's caused by a lock contention on the UDP receive buffer side. setData(newbuffer);. Learn how to use Wireshark, the powerful protocol analysis tool, to deal with packet loss and recovery, so you can keep traffic moving. So I assumed that random UDP packet loss isn't the issue (if I lose a few packets out of many, it's not a big threat), but I currently l. Hello, I am first timer to the forum and wonder if you can help me. In this example, you will use your Ethernet Shield and your Arduino to send and receive text strings via the UDP protocol (Universal Datagram Packet). After 4h-2d(random) the servers shows: Host did not receive UDP packet for everyone who's connecting. Packets may be reordered or duplicated before they arrive. Is there a way to stream a level in (Using LoadLevelInstance) without it creating/saving new levels on disk. Net; using System. Understanding MTU, MSS, Frame / Packets / TCP and UDP - From a beginner perspective (confused) Hi all, I have read around extensively but i am still not able to grasp the actual relationship of the above. Instead you send and receive packets of data. The following scenarios are several examples when you might consider using UDP broadcasts:. Re: Unity Client stops receiving UDP after a while Post by HumanPoweredGames » Tue Jul 17, 2012 3:35 pm I thought I had replied to this a while back, but I don't see the post so I'm re-replying. Joldas Nursoltan. The udp multicast message passing system is built into a. Following a script. In our organization, we have two test machines running Windows XP. A good one is 29West. applying rotation to character using FRootMotionSource. If you can get the debugs from the other end, then you could see if the peer side is receiving the udp port 4500 packets. length); // Now loop forever, waiting to receive packets and printing them. this needs to work on Linux system Thank you in advance [SOLUTION] using PHP to send UDP packets. Why svchost. Streaming UDP Video This small test was originally implemented as a proof of concept to get streaming video for the Cyclops project. Could you post two short but complete programs, one which receives and. The Transport Layer can use two protocols: UDP for generic communications, and WebSockets for WebGL A JavaScript API that renders 2D and 3D graphics in a web browser. Calculate the number of bytes successfully transmitted. Packet Sender is an open source utility to allow sending and receiving TCP and UDP packets. This article aims to give the readers a quick grasp of raw sockets idea, its design internals, and its successfull implemenatation BSD Raw Sockets API. Receive' naturally blocks, so you should spin up a thread to do this on, and exit the thread when it's done. I appreciate if anyone can help. The optional size parameter specifies the maximum size of the datagram to be retrieved. UDP is is a stateless connection where single packets get sent. Then I am using a script to send OSC UDP messages out which contain the coordinates of that object as it moves. If you only need to construct the UDP header then use IPPROTO_UDP as the protocol. Since the port 500 packet that you are receiving is a duplicate of the previous packet it is definitely not a reply packet for the port 4500 packet. In Ubuntu, that's nc. I'm using NetServices API. I used the following : AT+CIPSTART=1,"UDP","192. for UDP hole punching. The client does ask to confirm. mListener = new IPEndPoint(IPAddress. If it uses the UDP protocol to send and receive data, it will use a UDP port. I belive StackTask() function only give the status of the packet receive and send. Any packets you receive should be to base. NET Framework. User Datagram Protocol (UDP, RFC 768) •Same service (or lack of) as IP –connectionless, no state maintained –unreliable, no notification of arrival (datagram may have been discarded, duplicated, or delivered out of order) –no flow control (source may transmit faster than destination is able to receive) •UDP adds to IP. With each sample, the block outputs the contents of a UDP packet as a data vector of the size that you specify in the Data size (N) parameter. Second, a byte buffer and a DatagramPacket is created. My program receive UDP packets. 0 packet receive errors 1024731 packets sent TcpExt: 592 invalid SYN cookies received 396 resets received for embryonic SYN_RECV sockets 2 packets pruned from receive queue because of socket buffer overrun 3 ICMP packets dropped because they were out-of-window 2166428 TCP sockets finished time wait in fast timer 2773 time wait sockets recycled. ESP8266 Send / Receive Binary Data using UDP Introduction This is a quick introduction into using the ESP8266, more specifically the NodeMCU Dev Board, to send data in binary format over an existing WiFi network. I have only four packet filter rules for wireless device access. Packet Sender - Send / Receive TCP / UDP: Android app (4. The server and the client can be run on the same machine or on different machines. If you change MaxPacketSize to a value of 1, you force the client to use TCP to send Kerberos traffic through the VPN tunnel. I've looked at tons of examples and everyone seems to receive data in a different way. Since UDP is a connectionless protocol, as I explained earlier. Реализация UDP на C# using System; using System. You can have two different processes listening on both TCP and UDP port 80, without any conflict. The mainline branch officially supports Windows, Mac, and Ubuntu Desktop Linux. 4 --data-length 1550 UDP mode, to port 2090 at address, with a packet length of 1550 bytes. While the data link layer carries the point-to-point connections and the network layer carries the routing of packets, the transport provides end-to-end communication services for applications. Using the Transport Layer API. This is what I tried, but I guess there’s something wrong with this, cuz it does not receive any packet. Each message to a number of different key, subcontracting, subcontracting to a packet sequence number, the sender sends the sub gradually, over a period of time to check whether the received packet response, did not receive a response packet, to send. By default, receiving UDP Multicast packets from Android is disabled. kilobytes vs. This app doesn't work on other platforms (32bit etc), hence I want to recreate what this app is doing. Both work in linux machine (actually I test in same Cygwin can't receive UDP packet using recvfrom | Physics Forums. The protocol was designed by David P. 0 packet receive errors 1024731 packets sent TcpExt: 592 invalid SYN cookies received 396 resets received for embryonic SYN_RECV sockets 2 packets pruned from receive queue because of socket buffer overrun 3 ICMP packets dropped because they were out-of-window 2166428 TCP sockets finished time wait in fast timer 2773 time wait sockets recycled. Steps to reproduce: 1. I am looking for a simple example of UDP receive that can control say a small ball in Unity. Arduino UDP Multicast. Calculate the number of bytes successfully transmitted. Next, learn how to receive this data in Unity. We're using it as a logging system, and don't care too much since it goes from one computer to an internal switch, and right back to the other system. 6, i can't receive UDP packets correctly. receive(packet), so it's still running. Receive messages on the server. m program uses Matlab's ability to call Java code to enable it to send and/or receive UDP packets. (When receiving, remember to use large enough buffer, your network MTU or larger. In this two-part article series I am going to show you how to implement a simple client-server chat application using asynchronous UDP sockets. -X prints out the data in the UDP packets in ASCII as well as hex. In this tutorial I'll be showing you exactly how you can set up your own UDP chat server using CPython 3. A UDP socket in the connected state will only receive datagrams that originate from the given remote address. If the UDP object is connected, only datagrams coming from the peer are accepted. * This was created to work with the program UDP_Minimum_Talker. Even though as an industry we are moving toward software-defined everything and automated solutions, there will always be a need to know what’s going on under the hood (doesn’t our industry love […]. You send a message off into the ether, you might listen a period of time for a response, and the payloads are small enough to fit in a packet. These are typically used in applications that require little overhead and that want to achieve higher network throughput, such as multimedia streaming protocols. I used Vivado 2016 to create a hardware design (invoking GEM0), which I then imported to t. NatNet servers and clients can exist either on a same machine or separate machines. Very, very fast. User Datagram Protocol Definition. Simple searches use one or more words. This parameter is the UDP port the DatagramSocket is to receive UDP packets on. This tutorial waits for a UDP packet on a local port. UDP is connectionless. UDP Sender / Receiver. Now my wireless has the following issues: Packets sent but no receive! Problem aquireing IP address. Here is an example. Tutorial 4 Speakers: Liu Zihan ([email protected] C# sends and receives UDP broadcasts. Simple searches use one or more words. I copied methods I liked and thought would work for me and put together this method. If you choose UDP as the transport protocol for your cluster service, you need to configure it in the UDP sub-element in the JGroups Config element. UDP like TCP is a protocol for packet transfer from 1 host to another, but has some important differences. /** * A simple datagram client * Shows how to send and receive UDP packets in Java. Java code for a simple UDP server. User Datagram Protocol (UDP) – A transport layer communication protocol that uses a connectionless approach. User Datagram Protocol is a simpler message-based connectionless protocol. I have two modems (do not ask, some special stuff), that uses dial up (PPP) connection. make sure you use the traditional netcat. - UDP Sender / Receiver is a simple utility application that allows you to send UDP datagrams to another client or allows you to just listen for UDP packets. UDP Multicasting is a great way to send around data but there are a few things to look at to determine if this method is right for you. I have observed that B4A does not receive UDP packet unless and until sent sub is not executed. With each sample, the block outputs the contents of a UDP packet as a data vector of the size that you specify in the Data size (N) parameter. It is therefore feasible to use functions such as read or recv in place of recvfrom.