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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Hardware/topology recommendations for low latency UDP network

I'm setting up a LAN comprised of 60 end nodes that are receiving a high volume of UPD datagrams from one master server. The server sends 60 unique datagrams every 100ms, each datagram is 64 bytes. ...
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12k views

OpenVPN failing on self-signed certificate over udp, works over tcp

I have the following server.conf: # OpenVPN 2.x config proto tcp port 1194 dev tun-vpn dev-type tun server 10.8.0.0 255.255.0.0 push "route 172.16.0.0 255.255.0.0" push "dhcp-option DOMAIN mydom....
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1answer
181 views

Interactive shell based on SSH and UDP [closed]

I've heard from a friend about a client-server application which initializes on top of SSH connection but implements interactive shell over UDP protocol. It is specifically designed for bad quality ...
2
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1answer
772 views

Tactic to block a UDP spoofing attack

The packets are margin of 200,000 ~ 800,000 per second and UDP spoofed(0 bytes/46bytes) I have a linux deb 6 and windows server 2003 that is taking a hit. Current idea: - Setup a proxy server up ...
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1answer
490 views

How to block specific UDP packet outgoing from machine using iptables

I want to block specific UDP packet OUTGOING from my machine using iptables. Packet has a string in "hex in RAW"(?) i want to check packet by it. Like: If UDP packet hex RAW match "test_text" - block ...
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3answers
7k views

Netcat UDP File Transfer?

Is there any way to send a file (picture or video) using Netcat and UDP. It defaults as TCP, but I would like to send using UDP. I tried simply adding -u to the nc command, but that didn't work. Here ...
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1answer
816 views

enable large DNS queries on Microsoft 2008 R2 DNS server

When I run the Network analyzer at http://netalyzr.icsi.berkeley.edu/ it reports: The resolver at could not process the following tested types: Medium (~1300B) TXT records Large (~3000B) TXT ...
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215 views

Segments/Processes running on same UDP socket

Suppose a process in Host C has a UDP socket with port number 12345. Suppose both Host A and Host B each sends a UDP segment to Host C with destination port number 12345. Will both of these segments ...
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1answer
991 views

Creating a simple UDP listener [closed]

The situation is this: I'd like to make a hole punching server for a game and I need to listen to UDP traffic. It will run on a Debian Squeeze VPS so I'm pretty flexible as far as possibilities go. ...
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2answers
3k views

Need a live UDP echo Server IP and port

I require to test my UDP program using echo server. I have tested this application in LAN but now I require it to test it in Internet. Is there and globally recognize freely available well known ...
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1answer
162 views

Is throughput on higher bandwidth networks hindered by smaller UDP packet size?

I recently conducted an experiment on UDP throughput across 802.11g networks, using packet sizes between 100 and 1000 and bandwidths ranging from 6Mbps and 54Mbps. I have noticed that that higher ...
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169 views

Script to find the address udp packets are being sent to?

Here is the scenario. I have an IP address 1.2.3.4 port 2000 sending udp packets to one unknown IP. I would like to find the unknown IP so I can block it with iptables. Is there a way to do it with ...
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2answers
1k views

IPtables: is there a minimum UDP packet size for a DNS lookup?

IPtables for a virtual dedicated server. I would like to block UDP scans and I was wondering whether there's a minimum packet size for a DNS lookup? Nmap sends 0-byte UDP packets (source : http:...
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3answers
2k views

Limit UDP connections per IP iptables

I want to limit connections per IP for a specific UDP port. I got it working for TCP, but somehow it doesn't work on UDP. These are my rules: For TCP (working) iptables -A INPUT -p tcp --syn --...
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1answer
5k views

Block all incoming DNS requests EXCEPT from IPs x,y,

I want to block all incoming requests on my two DNS servers APART FROM certain IP addresses e.g. IP of 1.2.3.4 will be allowed to make requests but NOBODY else will. How do you do this with iptables? ...
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2answers
39k views

Does traceroute use UDP or ICMP or both?

When I do a trace on the www.google.com domain from my laptop, am I using icmp or udp ? I thought it was icmp type 11 but while searching for something else I came across rules where icmp type 30 was ...
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1answer
313 views

Very strange localhost connections on linux workstation. Need help identifiying the source

The following is the output of netstat on a Ubuntu machine. Can someone help decrypt the output? I am especially curious what the ::1:43213 connection is. Also, why are there so many connections ...
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1answer
1k views

How to measure UDP socket buffer loss on Windows Server 2008 R2?

Is there a way to view/measure UDP socket buffer loss on Windows Server 2008 R2? I've tried 'netstat -s' and looking at available perfmon counters, but nothing jumps out to me as a measure of socket ...
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783 views

TCP what's the purpose of the third step of 3-way-handshake [duplicate]

Possible Duplicate: Why is it 3-way-handshake and not more? Example: If a client wants to talk to a server, it just tells the server that it wants to establish a connection, then the server ...
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3answers
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Why is it 3-way-handshake and not more?

TCP uses the 3-way-handshake mechanism. I understand how it works pretty well but I wonder why it's not 4, or even 5-way? Is it because that's too much overhead and is not needed?
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1answer
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How to create UDP proxy using iptables

I have a server running UDP server on port 50000. This server receives updates from clients, and pings back the clients every 5 seconds to the socket they were connected from. Now I want to redirect ...
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2answers
1k views

How can I find out where a UDP connection fails?

I want to setup a VPN server with OpenVPN, so client PCs can access each other like they were in the same physical network. One problem I encountered is, that I cannot connect via UDP. When I change ...
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1answer
831 views

What is the difference between bind, network (interface) and multicast addresses?

The DatagramSocketImpl in Java has a joinGroup method that takes a socket address (IP and PORT) plus the interface address (IP and PORT). I am trying to understand the difference and purpose of each ...
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365 views

How to sniff udp between two windows applications on the same machine

How do I monitor the duplex udp traffic between two apps on my windows machine.
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1answer
680 views

Block UDP traffic by rate/string-match on Windows 2008

I am administrating a Windows 2008 server (64-bit). It is being subjected to a focused set of DOS attacks where UDP packets are sent to a specific port and contain a specific string. What I need to ...
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1answer
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tcpdump udp data capture latency

I am using tcpdump to capture UDP packets and analyze network latency between a UDP broadcaster and my server. To calculate latency I compare the source host timestamps reported in UDP application ...
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2k views

Iperf udp test show only 50 % of bandwidth

I test bandwith with iperf. I set up UDP protocol. I'm trying to setup limit from 10 to 100 megabit/s. Until 90 megabit max speed is correct. When I write -b 100m or don't write this speed become ...
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2answers
2k views

Https tunnel for carrying TCP and UDP packets

I had an issue with running Openvpn over UDP in my college network. The firewall was dropping UDP connections. As http and https were working fine and assuming that the firewall was inspecting packet ...
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3answers
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Troubleshooting UDP multicast on Windows

I'm a programmer, not a system adminstrator, so please forgive my administrative naivete. My software, written in C#, relies on UDP multicasting. One machine, the server, streams events to an known ...
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Is there any way to set PPTP on UDP Protocol? [closed]

In our network,many web site has been filtered ,so we should use VPN or Socks ,They reduce any tcp connection speed by dropping random packet (Than post and get on http),So ssh,pptp and ... are so ...
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1answer
496 views

ICMP destination unreachable

I am working on an arch linux machine with ethernet interface eth1. I have created interface eth1:0 using ifconfig and given it a dummy hw address (00:01:02:03:04:05). When I send a UDP packet to a ...
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2answers
858 views

Some questions on UDP send receive buffer, and networking

I have two debian servers located on the same subnet. They are connected by a switch. I am aware the UDP is unreliable. Question 1: I assume the link layer is ethernet. And MTU from a standard ...
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1answer
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Filter incoming traffic to UDP port for pci compliance

It had been recommended for PCI compliance that I filter incoming traffic to UDP port 5353 please can someone advise what are the steps to do this? I am currently using Centos 5.7 64 bit.
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How are UDP source ports selected?

I just did a packet capture from my machine and filtered out all the UDP connections. I saw certain connections using what appears to be a randomly generated UDP Source port, and certain connection ...
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62 views

Listing TCP/UDP process from an organically grown application

I've been asked to compile a list of TCP/UDP and ports they use for the collection of application that comprise our product for a client who wants the information for their firewall. So I fired up ...
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255 views

Service to temporarily queue UDP packets

I have a service running on a linux box that receives a fairly constant stream of packets via UDP. The occasional loss or corruption of packets associated with using UDP is fine. However, the service ...
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5answers
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How to list all requests to udp sockets?

I'm operating a couple of server daemons that use udp to communicate with large number of clients. How do I find and list out all the active udp "connections" that are talking to the servers in order ...
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2answers
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UDP and NATs - is the timeout bidirectional?

Is the timeout for an UDP connection through a NAT reset every time a packet is sent OR received by the client, or are there any (common) implementations that require the client to actively send ...
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540 views

NAT UDP Hole punching beginner's basic Qn

Is there any simple example of UDP-NAT hole punching, capable of hole punching for 2 peers communication via internet? I am trying to do UDP hole punching so that it would be possible to NAT traversal....
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How are UDP datagrams that don't have me as a recipient reaching my server?

I have a bunch of UDP datagrams reaching my server that look like so: The question is, my IP is not 208.69.57.21, (it was 208.69.57.101) so how are those datagrams even being received/logged by my ...
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4answers
306 views

Connect to internet via udp protocol

Is it possible if firewall blocking all http trafic but udp protocol is open connect to internet? because skype use udp protocol to connect and users can use skype. But is technicaly possible to cheat ...
0
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2answers
1k views

How to optimize TCP / IP stack in Linux? [closed]

Currently I noticed there are about 15K open connections to localhost. It is mainly connecting to Memcached. I am clueless where I should start to optimize TCP/IP stack. Memcached support UDP, but ...
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2answers
210 views

Finding the executable sending packets to a specific IP Address?

We host Game Servers off of Windows Server 2008 machines, and we just received a report that one of our customers is using their server to do some type of UDP attack. The person being attacked ...
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1answer
399 views

Why would a UDP socket perform OK on wifi, but not on a cell network?

Noobish question - I have a perl script running on a linux server which opens UDP port 7015. netstat -ulnp shows: udp 0 0 0.0.0.0:7015 0.0.0.0:* ...
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2answers
136 views

NetBIOS over TCP/IP with no UDP

Is there a way to run NetBIOS entirely on TCP? I have an environment where UDP is not allowed. I need a way for the machines to talk to each other by name. I thought there might be a way to say that ...
7
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1answer
3k views

iperf max udp multicast performance peaking at 10Mbit/s?

I'm trying to test UDP multicast throughput via iperf but it seems like it's not sending more than 10Mbit/s from my dev machine: C:\> iperf -c 224.0.166.111 -u -T 1 -t 100 -i 1 -b 1000000000 ------...
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1answer
170 views

What settings should I modify to tune a Linux server for very small yet very high packet rate UDP receive loads?

I am tuning a server that needs to handle small (average of about 50 bytes) UDP packets. The average packet rate is approximately 100,000 packets/second. The data is very burst and can sometimes burst ...
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3answers
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Where is the documentation that states TCP and UDP source port should be over 1024 and random?

I am having a hard time to find where it is documented that the source port should be random and in the range 1024-65535. In which RFC is this documented? Edit: First reference for privileged ports ...
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2answers
366 views

Strange UDP/TFTP Problem

My TFTP client only seems to be getting responses from the TFTP server to its RRQ (download requests) if I watch the traffic in wireshark. If I shut down wireshark (running on the TFTP server), the ...
0
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1answer
104 views

tc: packets filter

I need to drop UDP packets with specific UDP port number) on network interface (say eth0). On my setup the interface eth0 is part of the bridge. is it possible to do it using tc command? if yes, how?