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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udp packet delays in my dedicated WIFI network - can i force UDP nodelay over wifi?

I have a dedicated app and network development for passing UDP packets over a wireless network. The totality of the network is a PC (Mac OSX or Linux) which sends the packet-->router/AP-->WIFI device....
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1answer
581 views

UDP Packet Size.. max, ping failing to 3G.. Recalcitrant software vendor

We have a network of 330 clients (Service Vans) connected via 3G to our central office. Currently these clients are connected via a small ruggedized 3G router that establishes the 3G connection and ...
2
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1answer
322 views

How to setup routing for UDP in AWS instance

I'm new to AWS and I'm wondering if any one could provide a guild/link on how to go about setting up, what I'm guessing is VPC, so that I can send UDP packets to and from my instance via my public IP. ...
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1answer
108 views

Monitoring /proc/net/udp

I am interested in tracking changes in /proc/net/udp, particularly in the "drops" column. I want to know the the approximate time when a drop counter goes up. Also, if the socket gets destroyed, I ...
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1answer
951 views

UDP maximum segment size

Environment: I am writing a UDP client-server application. the path MTU between client and server is 1500 bytes (with only a wireless link between them, so this value is pretty much stable). My system ...
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1answer
616 views

Firewall UDP Flood Dos/DDoS

Recently I have been suffering from what appears to be a UDP query flood attack. I am looking for a way to block the attack using a software firewall such as iptables, this should be possible, as ...
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1answer
101 views

Redirect packet that matches a pattern?

How can I route an incoming udp packet with iptables that matches a pattern like: 53 41 4D 50 5B 79 95 DB 61 1E 69 from public interface (vmbr0) and port 7777 to 192.168.0.1:7777?
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1answer
117 views

Debian 7.4 drops UDP traffic randomly

I'm running Debian 7.4, KVM VPS with the latest updates. I'm getting UDP ports randomly closed for 2-10 minutes for no reason. I'm running gaming servers and the port tester shows the ports are closed....
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687 views

Serious Packet Loss on UDP using Amazon EC2

I am using ec2 to host a udp TURN server for SIP purpose. Anyway I get a lot of packet loss during voice call, so I did a udp performance test using iperf util. Result: [ ID] Interval Transfer ...
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1answer
524 views

UDP packets dropped

A host sends UDP broadcast, but its UDP packets are not received by any other hosts in the same subnet. However, its TCP traffic with others hosts are OK. I observed this using tcpdump. Could it ...
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1answer
317 views

port forwarding to access services on servers behind NAT

I have some security camera systems in different locations, each location does have internet, the ISP is NATing all the IPs so theres no way to open ports to my systems. My solution was to rent a VPS ...
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1answer
53 views

Why are duplicated UDP packets being dropped 10 out of 11 times by this iptables configuration?

I am trying to duplicate UDP packets flowing to port 50007 on an Internet address from devices on a local NAT network (192.168.12.0/24) with the intent of processing them locally (on 192.168.12.1:...
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97 views

Caching UDP packets with iptables

I have a server set up to forward all of its packets on a certain port to another host with the following command; iptables -t nat -A PREROUTING -p udp --dport PORT -j DNAT --to-destination IP:PORT ...
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1answer
48 views

How does acting as an RDP host affect UDP visibility/routing?

This is an odd one. First, THIS IS NOT A NETWORKING ISSUE. This is an "rdp host behavior" that can be seen, from one persective, via the behavior of an RDP app. (see What happens to a Windows 7 ...
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1answer
580 views

UDP packet loss cause

I have two machines connected to the same LAN and multicasting UDP streams at rate of about 30Mbps. Analyzers often show packet losses on one machine, but never on another. What could be the reasons ...
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1answer
854 views

Set udp packet size limit

I have a CentOS server with a JAVA application that receive UDP data packets, it works all OK until the packet is bigger than 584 bytes, I read something about and seems to be a limit of UDP protocol. ...
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673 views

UDP Overflow / UDP Drops on Standby Postgres Service

I am stumped trying to prevent an overflowing UDP buffer on a standby Postgres service. Any help would be most appreciated. Essentially a UDP buffer associated with the pg_standby process on my ...
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0answers
244 views

How to resolve UDP packets being dropped given netstat reporting SndbufErrors

I have a server instance on an OpenStack that at a pretty high load starts loosing UDP packets. I captured all outgoing packets using tcpdump and some of them are missing, even though application logs ...
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0answers
128 views

How to use an IPv6 Edge router in an IPv4 network?

Background I have the following set-up: I use 6LOWPAN (IPv6 implementation in IEEE 802.15.4) on my sensor link that have IPv6 addresses (stateless) as aaaa::xx/64 It uses RaspberryPi (RPI) as an ...
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0answers
267 views

Why is qemu issuing a DHCP discover after it receives a DHCP offer

I'm having some trouble seting up network on qemu. I'm trying the easy option (user). The qemu command I run is this: ./qemu-xilinx/arm-softmmu/qemu-system-arm \ -M xilinx-zynq-a9 -m 1024 -...
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0answers
2k views

Forwarding udp ports iptables packets “lost”?

I have a Linux router (Debian 6.x) where i forward some ports to internal services. Some tcp ports (like 80, 22...) are OK. I have one Application listening on port 54277udp. No return is coming from ...
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7 views

Is there a non-invasive test of uPnP enabled network?

I'm trying to figure out if there is a way to do a non-invasive test on different networks to see if Universal Plug'n'Play (nPnP) is enabled at the router. i.e. Is Internet Gateway Device Profile ...
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13 views

Is there a way to tell a machine accesible via a gre tunnel to join multicast groups via pimd or smcroute?

this has been stumping me for some time and would love any help on this. So I am subscribed to a data vendor through an intermediary firm. The intermediary firm has physical connections to the data ...
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63 views

Joining a UDP multicast through a server on the other side of the tunnel

I've drawn a diagram below to help with this question! So a company published a multicast UDP feed (company A) and another company connects to it (Company B). I have a point-to-point tunnel to ...
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31 views

rx_queue value in /proc/net/udp grows to twice the SO_RCVBUF value

When using an SO_RCVBUF of 10485760 (which is also the current limit as stipulated by sysctl's net.core.rmem_max setting, and sending UDP packets faster than the receiving side is able to handle, the ...
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352 views

UDP packets seen on interface level but not delivered to application on RedHat

I have a problem with receiving UDP traffic on a RHEL6 server. When capturing the traffic with tcpdump, the packets are visible (checksums are correct, the destination IP and MAC match the machine's ...
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232 views

Multicast works only in promiscuous mode

I'm trying to receive MPEG-TS over UDP multicast transport in Arch Linux. So when I run ffprobe -i udp://@224.1.1.240:6000 it hangs forever with no result. Then I run tcpdump and it shows no ...
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361 views

Firewall rejecting UDP “connections”?

I have a server that is aggregating logs from various other servers. It mostly works great, however from time-to-time (right after a reboot, but not all reboots) it will decide that various UDP "...
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104 views

UDP sends 6 additional packets in Wireshark

I am sending UDP packets using ttcp to another machine which is connected via a Cisco router. However, when I analyze the packets sent in Wireshark, there is a UDP packet sent before the payload ...
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68 views

Nat Traversal, peers unable to communicate

I'm currently working on a project that requires NAT traversal but I seem to be running into difficulty. I have the following setup running for testing: R1, Verizon Fios router connected to the ...
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407 views

UDP socket receive buffer size change on RHEL6.3

Our system used to work on RHEL5.3 And the socket receive buffer size is 64k. And that works fine. We can get message size up to 64k on UDP socket. But after system upgrade, it is running on RHEL6.3 ...
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3k views

UDP Multicast not working without promisc. Already tried rp_filter=0

I'm having issues with multicast traffic in Ubuntu Maverick. It only appears to work when the card is in promisc mode (i.e. if I set it manually, or use a tool such as tcpdump). Adding multicast ...
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90 views

tcpdump strange udp line

I've found a strange line in the tcpdump output. Normally UDP packets are dumped in the following form: timestamp IP srcaddress.port > dstaddress.port: UDP, length packetlength but this is just: ...
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22 views

Can't bind UDP socket but port is free

I've been struggling for a while now with this so maybe someone here is able to help me. I'm setting up a CS:GO server that's going to be running on port 27059. (This is a copy&paste from a ...
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13 views

UDP destination address during port forwarding?

I have setup a connection using Qt in the LAN, PC1(192.168.1.195) will send UDP packets to PC2(192.168.1.201) with no problem. But now, PC1 and PC2 are now working under different routers. So now PC1 ...
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23 views

Packets not being delivered to application

First of all sorry if this is not the right place. So... I have a problem. I'm working on a linux board (the distro is created with yocto, kernel is 3.10.17). I have several network interfaces (WWAN1 ...
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38 views

netcat UDP port test response issue

I am running a game server on a Windows Server 2008 VPS/VDS through port 12203. I want to be able to automatically restart the game server exe file if it crashes. So, my strategy is to use netcat to ...
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87 views

UDP Port Forwarding Error: channel 2: open failed: connect failed: Connection refused

My situation is as follows: I have currently trying to have a program between two Hosts send UDP packets over a SSH Tunnel. There is also a host intermediate between the two hosts. Note Server01 ...
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85 views

How to prevent outgoing UDP flood

I've been googling for hours now but can't find a sure or helpful answer. I need to disable high-volume outgoing UDP from my server. I'm trying to configure APF because of the RAB functionality, but ...
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0answers
62 views

Colasoft Packet Player with Loopback-Adapter - Cannot recieve UDP-Packages

I have some problems with Colasoft Packet Player. I am trying to send the UDP-Packages over a Loopback-Adapter (Windows 7, I want to send and receive them over the same computer) and to read them with ...
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882 views

Enable UDP protocol in Remote Desktop Connection

I have a computer to which I am connecting via RDP. However, using the default Windows applications (Remote Desktop Connection) probably will not use UDP port. By clicking the connection information ...
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12 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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555 views

Fast Ethernet UDP optimize receive buffers

I have a Linux computer which must receive streaming data from several devices (up to 30 or so) during long terms. This computer is connected to a Fast Ethernet local area network (100 Mbps) where ...
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0answers
65 views

RX errors when using jumbo packets

We have a device outputting high speed data over UDP connected directly to a processor (no switch). The processor is running CentOS 6.6. The connection is gigabit Ethernet. When we use packet sizes ...
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346 views

Piping device file over UDP with netcat

Hopefully this is the best Stack Exchange site for this - I think it's primarily a netcat question. I'm developing a custom data acquisition device. It can probably be best thought of as a fancy ...
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189 views

Does Ubuntu with Linux 3.5 having TX RX ring buffers or BQL

My linux uname -a command outputs: Linux Davinci001 3.5.0-23-generic #35~precise1-Ubuntu SMP Fri Jan 25 17:13:26 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux So, does NICs with this Ubuntu machine is ...
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1k views

Linux: Reduce UDP Packets Error

I'm facing UDP packet receive errors (under Linux 'netstat -su' command). I have 10 x UDP processes running on Machine-A (RHEL 5.2) and each of them send 290-byte packet at 50 times per second to ...
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111 views

How can I log and maybe even block IPs that send lots of incoming UDP traffic?

we run a voice / teamspeak server which receives legitmate traffic on port 9987 from many ips. Sometimes we get DDoSed. So people use single Servers and send 1-3 Gbits of UDP Floods to that port. This ...
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93 views

How to turn a UDP feed on and off?

I have a linux application that is sending a stream of UDP packets to a particular ip and port. I need a way of suppressing this packet stream so the packets never reach the network, with the ability ...
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454 views

How to forward UDP and TCP traffic from one IP to another

I have a server with two LAN cards installed. I have one server in U.S and one in India. I have created a GRE tunnel to route all traffic from the U.S Server to my Indian Server. My traffic has UDP,...