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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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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1answer
471 views

one particular laptop does not receive UDP broadcast messages

I am trying to debug a problem with a particular laptop which is running Ubuntu. We have a service which uses broadcast UDP messages, and this laptop is not receiving them on its wireless interface, ...
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1answer
2k views

Reverse proxy for mixed tcp, udp, and http services

I'm building an architecture that will be hosting various services which individually maybe listening on a variable number of ports that could be mixed protocols. I want to map these services to ...
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456 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 ...
3
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1answer
444 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
160 views

Interactive shell based on SSH and UDP

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 ...
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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 : ...
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1answer
2k views

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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4answers
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How does UDP track connections?

If UDP does not establish a connection as TCP does.. it seems the only way it could track connections is source ip/port and destination ip/port. Is this correct? So, I guess there are special packets ...
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2answers
174 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 ...
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2answers
413 views

Multicast IP Addresses

I posted this on StackOverflow and was told it might be more appropriate here. I'm having trouble understanding how multicast addresses work. First off, is it true that if I have N clients or peers ...
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3answers
5k views

Wireshark won't pick up packets sent from localhost to localhost via network [duplicate]

I'm running on Windows and trying to get Wireshark to pick up my network traffic. It picks up all outbound and inbound traffic fine, except for a client/server I'm running on my local system. As it ...
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2answers
109 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 ...
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1answer
3k 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" ...
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2answers
4k 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
232 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 ...
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1answer
63 views

Is Linux limiting my application's UDP transfers, and how can I see it?

I am currently developping two applications to work over a custom video streaming "protocol". Basically: The server captures video frames from a webcam, slices them into parts, and sends these parts ...
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1answer
149 views

UDP Proxy with cloned packets

Having UDP messages sent from dynamic public IP periodically to public IP X:20000. Need a proxy that listens in IP X:20000, then forwards duplicate/clone packets to X:20001 and a different machine ...
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2answers
168 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 ...
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1answer
647 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
1k 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 ...
2
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1answer
497 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 ...
2
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1answer
2k views

Forward broadcast to fixed IP using IPTables

I need to forward (route) broadcast packets from several wireless clients to a single server in the fixed network. The wireless and fixed network are not bridged for security reasons. With the ...
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3answers
3k views

Why isn't my ip helper-address helping?

I have a hub site with a Cisco 2811 and several remote sites, running a mixture of Cisco 851 and 871 routers configured for site-to-site VPN. I am in the process of adding DHCP scopes and DNS zones ...
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2answers
2k views

Broadcast UDP over VPN

I have OpenVPN configured and have 5 dd-wrt router clients. I would like the machines on those routers to be-able to UDP Broadcast across all 5 networks. I cannot bridge the interfaces(to my ...
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2answers
5k views

UDP traversal through router automatically without router port forwarding?

Everyone knows the router is working like a firewall. Without port forwarding, a connection (no matter TCP or UDP) cannot be initiated from outside of the router. However, if a user initiate a TCP ...
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2answers
249 views

Can IP spoofed traffic get above the transport layer?

I'd like to know whether you could get packets with a spoofed IP address above the transport layer. My thoughts are: TCP: No, as acknowledgements would never get to the original sender if their IP ...
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2answers
9k views

What is the default TCP window size on Windows Server 2008?

What is the TCP (and UDP) default window size on Windows Server 2008? I think it's 1480 bytes, but I'm not sure. Can it be changed? How?
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1answer
792 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 ...
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2answers
2k views

Can I test broadcast packets on a single machine?

I want to have a server sending broadcast UDP packets and two other clients, in the same machine, receiving them. Can I do that somehow? What IP address would I use? @gravyface gave me hope but I ...
2
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1answer
526 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 ...
2
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1answer
675 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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1answer
1k views

Protecting against UDP flood

One of my servers is being flooded with udp packets on random ports. 12:11:54.190442 IP 182.48.38.227.60173 > localhost.51523: UDP, length 1 12:11:54.190447 IP 182.48.38.227.60173 > ...
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2answers
985 views

Netcat, Syslog, UDP, and <134>

Listening with netcat on UDP 514 to syslog data I see that each sent log message is separated by <134>. Does anyone note what <134> is?
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1answer
126 views

UDP Socket bound to one IP?

Say I have two hosts - Using fictitious IPs for this example, say host A has IP 1.1.1.1. host B has two IPs - 2.2.2.2 and 2.2.2.3. If host B is listening on port 8888, and sees a packet come in from ...
2
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1answer
890 views

iptables -m string inspecting udp payload only

This is the rule I'm working with: iptables -A QUERY -p udp -m length --length 24:63 -m udp -m string --algo bm --hex-string '|ffffffff|' --from 12 --to 28 -j QUERYLIMIT Is there a way to inspect ...
2
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1answer
9k views

Verify connectivity to a server on a UDP port

I want to know if a HP-UX machine can communicate to a remote machine (which I don't have control over) on a particular port using UDP. I tried telnet, but it doesn't look like it supports UDP. I ...
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1answer
323 views

Set Windows Firewall to Stateless?

Is there a way to "dumb down" the Windows Firewall on Win2003 or Win2008 from stateful to "stateless", and have it only do basic port filtering on the public interface? If not, is there a simple, ...
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2answers
153 views

tcpreplay throughput on eth0 well below (iperf confirmed) max

I'm trying to replay captured UDP multicast packets at a rate of a couple of hundreds of Mbps, but it maxes out at about 86 Mbps. (For some strange reason, at other times during the day it ...
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1answer
5k views

OpenVPN Error : TLS Error: local/remote TLS keys are out of sync: [AF_INET]

Fist off thanks for reading this, I appreciate any and all suggestions. I am having some serious problems reconnecting to my OpenVPN client using Riseup.net's VPN. I have spent a few days banging my ...
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2answers
3k 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 ...
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2answers
503 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 ...
2
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1answer
481 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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2answers
1k views

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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2answers
1k views

Rate of UDP packet loss over WLAN

While testing something with TFTP I noticed lots of timeouts (and slow speed as result) when I used my WLAN - and no problems when using a network cable. A quick test program sending/receiving UDP ...
2
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1answer
968 views

Adding more than one IP to sip.conf tcpbindaddr and udpbindaddr (Asterisk 1.8)

The defaults in the sample sip.conf under Asterisk1.8 contain udpbindaddr=0.0.0.0 and tcpbindaddr=0.0.0.0. I want to bind the incoming [foo] extension to udp:192.168.1.1/255.255.255.0, the outgoing ...
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1answer
648 views

KVM virtualized CentOS can send/recieve TCP but not UDP

I've installed CentOS 5 inside KVN on FC12. I've setup a bridged network that works fine. I can ping the virtualized host from any of my other computers and the other way as well. I can also access ...
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1answer
33 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. ...
2
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1answer
27 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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0answers
29 views

Are DNS server responses categorized as “ESTABLISHED” by iptables? If so, why? [duplicate]

CentOS 5.x I'm trying to confirm which specific rule in my iptables config is allowing return UDP traffic from my DNS server. I THINK, it's this one: -A RH-Firewall-1-INPUT -m state --state ...