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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1answer
125 views

Cat a file(raw) to UDP at specific bitrate

I'm looking for a way to transfer a file over UDP at an specific bitrate. I can use netcat for example like this: cat file | nc -u 192.168.x.x 5000 And I use a custom application to listen at port ...
3
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2answers
561 views

Symmetric NAT and UDP Hole Punching

I've read this question, but the explanation of Symmetric NAT wasn't detailed enough. Please could someone help me to understand the following paragraphs? I read this about Symmetric NAT: Each ...
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2answers
72 views

NAT UDP port switching? [closed]

I've read about the Quake 3 networking code that they had to deal with a situation where some older NATs would randomly switch client ports. How common is this issue these days? Is it worth handling ...
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2answers
196 views

Can heavy UDP traffic create network congestion?

I have three IP addresses using the same gateway. Two of them are configured as a cluster with multicast address setup. If there is a heavy UDP traffic between those two, can that affect the network ...
0
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2answers
35 views

unicast traffic on windows server

I have three servers with IP addresses (10.15.23.23, 10.15.23.24, 10.15.23.25). Server 1 and Server 2 have Tomcat installed and are configured as a cluster listening on a multicast IP address ...
2
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2answers
128 views

In need of a SNMP repeater

I have a monitoring system that has primary/failover nodes for just about every aspect. I have configured anything that is able for multiple SNMP trap destinations, but I do have a number of devices ...
0
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0answers
198 views

Users can't send mail message - mx record for site getting Truncated, retrying in TCP mode

System setup: Linux Red Hat Enterprise Linux ES release 4 (Nahant Update 9), Postfix mail server I have a user who is trying to send an e-mail. E-Mail on this server has been working for years ...
2
votes
2answers
100 views

Minimal size of TCP communication

I am sending small amounts of data (up to 100 bytes) every 10 minutes from devices to TCP server. In my case overhead seems to be huge (we pay for each byte). I found that I have at least 7-10 packets ...
0
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1answer
51 views

LAN has two entry points - how to manage traffic

I asked this question yesterday when I (seemingly) couldn't get traffic across my router. I've spent a lot of time since then with packet capturing, the ASA 5505 cli/ASDM and wireshark. I've ...
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1answer
50 views

How to host a TCP / UDP service on the Internet which is currently running on my local machine? [closed]

I have created a TCP server and it's currently hosted on my local machine, but I want to host it on Internet like we host websites. Is there any company which provides this service? And what's the ...
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0answers
81 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 ...
2
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2answers
3k views

Reduce firewall rules by half - one iptables rule for tcp and udp

I have a number of iptables rules on my firewall that look like this: iptables -A zone_lan_forward -p tcp -d 1.2.3.0/24 -j ACCEPT iptables -A zone_lan_forward -p udp -d 1.2.3.0/24 -j ACCEPT Is ...
2
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1answer
488 views

How to force use of tcp instead of udp for rpcbind?

I'm trying to use tcp/111 for rpcbind under Debian Wheezy instead of udp/111. The portmap in Squeeze uses tcp/111 without any special configuration, but Wheezy fails. Even numerous sites (as well as ...
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vote
2answers
351 views

TCP vs UDP Error-Checking

I've bounced upon two articles that describe in-depth on how TCP and UDP connections work. However there is some kind of inconsistency. Where one article tells me that UDP does no Error-Checking at ...
1
vote
2answers
829 views

Per-packet round-robin load balancing for UDP

I need to load-balance UDP traffic between a number of "realservers" and do it in a truly round-robin fashion. I've started with keepalived, but unexpectedly discovered, that LVS treats UDP traffic as ...
2
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2answers
2k views

Traceroute, ICMP, UDP and TCP

When does traceroute use TCP? Or does it just use UDP, also why does Traceroute use UDP on MacX and ICMP on windows? I thought ICMP just contains a message saying what caused the error of a packet and ...
1
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0answers
48 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 ...
1
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1answer
335 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
2k views

How do I increase UDP Recv-Q

I have a gigabit connection that is not fully utilized but I am getting packet receiving loss. When I do netstat, it shows the Recv-Q sometimes maxes out at 262656 during heavy traffic. Proto Recv-Q ...
2
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2answers
161 views

What is the lowest udp source port for puppet dns queries?

On CentOS 6.4 and 6.3 I have seen puppet regularly use ports below 32768. This is contrary to the setting for kernel-assigned ports according to: cat /proc/sys/net/ipv4/ip_local_port_range 32768 ...
1
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1answer
317 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 ...
1
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1answer
64 views

Trouble with VPN Tunnel

How to direct a UDP Packet through a VPN tunnel? The router in question dose not have any features that would allow a UDP flooding or broadcasting, so for this project I am shooting in the dark, any ...
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1answer
1k views

openvpn tcp or udp (specific situation, reliability-layer collisions)

My question is whether to use TCP of UDP for my openVPN connection. I've set up a simple network for a startup company that allows users from the outside to acces the network via an openvpn server (in ...
0
votes
1answer
110 views

Is multicast appropriate for sending a copy of a video chat to a server?

I am creating a p2p video chat app using the libjingle/WebRTC code. I would like to collect a copy of these video conversations on our server for users to watch later - but I don't want to suck up too ...
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0answers
292 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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1answer
2k views

Is it possible to duplicate a UDP unicast stream with iptables?

I have a proprietary system which transmit a udp video stream from unit #1 (192.168.1.1) to unit #2 (.1.2). I can't make changes to this system, and I'm trying to clone this udp stream so I can access ...
2
votes
2answers
567 views

Solaris doesn't know which MAC address to use to send an UDP multicast message

I have a pair of Solaris 10 boxes which are supposed to send multicast UDP packets to a group of hosts. One of them works just fine, whereas the other one does not. The problem with the second ...
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2answers
311 views

Countermeasures versus incoming DNS reflection attack

i am currently experiencing a DNS reflection attack towards my server. I am getting a massive amount of answers via UDP from Port 53 that my server has never asked for: 02:53:57.626156 IP (tos ...
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1answer
1k views

Tool for forwarding UDP packets Windows

Windows Server 2008 I use portproxy interface to forward traffic , but I looked into the msdn page and I noticed it doesn't support udp protocol . protocol Specifies the protocol to use. ...
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0answers
101 views

Cannot see an EC2 VPN server from another EC2 instance

I'm using openVPN to connect to one EC2 instance from another. The client cannot see the server, however, despite that servers outside of AWS can see the server and successfully negotiate with it. ...
2
votes
2answers
465 views

How does SSL VPN (openvpn) connect via UDP?

I need to test whether an OpenVPN Service (ssl-vpn) is listening on a specific IP address and port from a linux box. I'd like to do that with a bash script or some code in python or c/c++ but that's ...
1
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1answer
221 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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3answers
159 views

DDOS protection from ISP side, UDP protocol, whitelist

Is it possible to ignore packets from ISP side which are incoming to my server? Is possible this kind of situation ? : I have white list of IP addresses. I continually update white list and sends it ...
2
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0answers
959 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 ...
0
votes
1answer
460 views

UDP packets to IP addresses other than specific ones not arriving and not shown in Wireshark

I'm writing a service using UDP, but I can't manage to reply to the client. When sending to the client via the DHCP-assigned IP (192.168.1.143) Wireshark shows no sent packets. The server receives ...
0
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2answers
300 views

nmap scan only state of port

Is it possible with nmap to check only the state of a port whether- open, closed or filtered and NOT the services behind it? The aim is to speed up scan results. Since UDP scan is also involved it is ...
4
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1answer
441 views

possible UDP attack on BIND?

hello everyone, i was surprised last month when my EC2 instance (ubuntu precise server), that is supposed to be under the free tier still, accumulated lots of traffic... today, while checking my ...
0
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2answers
3k views

Problems with MDNS flooding on port 5353 UDP

I am running into a big issue at a small network i manage. This network is an Apple network, with airport extremes, expresses, mac book pro's, imac's, ipads, iphones etc... I went to add something to ...
0
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2answers
1k views

iptables rules for botnet (UDP flood) protection

I'm currently experiencing a massive UDP attack on my server. I host a couple of gameservers, mainly Tf2, CS:GO, CS 1.6 and CS:Source, and my 1.6 server is being flooded. I tried different rules in ...
3
votes
1answer
373 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 ...
1
vote
1answer
402 views

Multicast in private LAN with different subnets

after i read Multicast IP Addresses and Multicast accross the subnets I am confused. Configuration: I have two devices in the same network. They may not be in the same Subnet, but ...
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votes
3answers
69 views

Two-way UDP on varying-IP networks

I've heard that on some corporate networks, outbound traffic from the same user can hop around different "from" IPs. Does that break two-way UDP, or do the networks only act that way for TCP? If it ...
1
vote
1answer
2k views

Why does VPN IPSec client use UDP?

The VPN I use on my home Windows computer to connect to my company's servers is a Cisco client. The client is configured to use "IPSec over UDP (NAT/PAT)". Why would you use UDP, an "unreliable" ...
0
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3answers
4k views

Why is UDP slower than TCP on Ubuntu Server?

I transfer data between two Ubuntu Servers (12.04) via iperf on 1Gb LAN. iperf -s <-> iperf -c <addr> -n2G TCP speed = 925 Mbits/sec iperf -su <-> iperf ...
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1answer
136 views

UDP flooding multiple servers [duplicate]

Possible Duplicate: What are the best techniques for preventing denial of service attacks? What do you suggest? Being UDP flooded as I write to multiple servers in different data centers ...
0
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1answer
177 views

Can NAT port change dynamically in an active session?

I am facing an issue, having client server application where client application is sending UDP data frequently to server and server redirecting back to the client. But in a few cases I am not getting ...
4
votes
1answer
700 views

HTTP, TCP, UDP and connectionless

I am a bit confused with HTTP lately. Some facts are that TCP can operate connection orientated or connectionless, this I understand. TCP though is connection-oriented while UDP is connectionless ...
2
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1answer
669 views

Tunnel only one program (UDP & TCP) through another server

I have a windows machine at home and a server with debian installed. I want to tunnel the UDP traffic from one (any only this) program on my windows machine through my server. For tcp traffic this ...
1
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1answer
607 views

Broadcasts from guest machine not reached host machine

I have an application that sends UDP broadcasts to some port, for example 11000 (BROADCAST_APP) and another application that listens the 11000 UDP port(LISTENER_APP). The apps works well on the ...
0
votes
1answer
1k views

Too much traffic on UDP suspecting bind miss-configuration

A server generates over 600GB of monthly traffic on UDP port (while http is under 1GB), so I ran tcpdump command and I see many (over 10/second or so) fast dns related commands/traffic that looks like ...