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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tftpd not working - MAC OS X El Capitan 10.11.5 [closed]

I use tftp in a daily basis, as part of my work. So far, so good, since yesterday (Jun 21, 2016) it simply did not worked anymore. I do not know exactly the reasons, because could not find any support ...
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1answer
53 views

Identify the ip to which an UDP port established connection

I'm trying to obtain the ip to which Rocketleague.exe has established connection on a UDP port. I've tried with netstat -p udp but for some strange reason it does not show any active udp connections . ...
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1answer
26 views

Udp port binding in VMware Linux

In my application, there're two physical computers, both in Windows environment. Computer 2 (with IP "192.168.2.2") has a VMware Linux virtual machine (with IP "192.168.80.129") installed on it. What ...
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1answer
24 views

Debugging dropped UDP messages on Linux

Here's my setup: I have 1 host that has a 1 Gbit Ethernet connection and 2 hosts with 100 mbit connections (connected to the 1Gbit host through different switches). In a test, I send 1000 1kb ...
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0answers
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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1answer
107 views

UDP hole punching still required in IPv6, even without NAT?

Background (skip ahead for question) IPv4 needed NAT for address conservation. The firewalling properties of NAT were also beneficial for security. IPv4 NAT firewall rules are "block incoming packet ...
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2answers
103 views

Receiving broadcast UDP packets under Linux

I'm having a similar problem to Linux Kernel not passing through multicast UDP packets only broadcast rather than multicast, and nothing I've tried has helped. I've got a device at 192.168.0.1 ...
2
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1answer
30 views

rsyslogd not listening udp 514

I have Debian 3.2.65-1+deb7u2 with rsyslog 5.8.11 udp 514 $UDPServerRun 514 and $InputTCPServerRun 514 are uncommented. Why it is not listening to that udp port?
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1answer
55 views

Iperf3 keeps hanging when running UDP test

I wrote a Python program that runs iperf3 in a for loop with different datagram sizes. I am using Python's subprocess.call function to run iperf3 like this: iperf3 -u -c 185.82.21.60 -b 100M -t 5 -l ...
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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 ...
3
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1answer
37 views

Segmentation fault when running nuttcp inside Docker

I am measuring the UDP throughput between two Docker containers that are connected by Docker's native overlay network. I already used iperf but also want to measure the throughput with nuttcp. But ...
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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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1answer
46 views

UDP Server behind Gcloud load balancer: receive ok, reply fails

I have a UDP server set up (on a VM) behind the Google Cloud network load balancer. The server is bound to 0.0.0.0. The UDP server can receive messages that were sent to the balancer, but replies do ...
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2answers
33 views

how to run memcached on UDP ports only

How can i configure memcached to run on udp ports only on centos box ? Right now it is listening on TCP ports by default. Here is my memcached configuration file. cat /etc/sysconfig/memcached PORT="...
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0answers
234 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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1answer
44 views

What is a TCP Relay and when is it used? [closed]

Tcprelay is a TCP connection forwarder with load balancing capabilities. If compiled with TLS support, it may be used as SSL encryption wrapper. What are some practical applications of TCP relay?
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1answer
63 views

bandwidth monitoring by TCP/UDP port on Cisco 2960 or Linux

We have an international line between two sites with limited bandwidth. I want to monitor bandwidth usage between the two sites, and understand which type of traffic consumes the most. Ideally I ...
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0answers
29 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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6answers
5k views

Why would a university block incoming UDP traffic with destination port 53?

From my understanding DNS uses UDP and port 53. What undesirable things could happen if incoming UDP packets to port number 53 weren't blocked? UPDATE: Packets originate or are destined to the ...
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0answers
122 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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1answer
41 views

udp broadcast on port 25860

I used wireshark on my local network (to test it), and i noticed that there is a lot of udp packets send one broadcast, and the majority is coming from only one host. Theses udp packets are send on ...
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1answer
69 views

How to make svlogd send logs via UDP

I am currently using runit + svlogd for supervising some applications, but when deploying to multiple machines, I have the need to centralize/unify the logs in a single place in order to simplify ...
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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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1answer
328 views

What are the ports needed for L2TP VPN on Mac OS X Server 5.0.15?

I'm configuring a Mac as a server with a VPN service. So, I opened the ports listed as used by VPN in Apple documentation: UDP 500 -> 500 (+ESP and AH) UDP 4500 -> 4500 Any UDP -> 1701 (I got to ...
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11 views

CentOS Drupal Site/Domain Sending UDP Attacks on Different IPs [duplicate]

My Drupal 7 site is hosted on a Cent-OS 6.5 VM. The hosting service provider notified me about an malicious activity on site and site is sending UDP packets on different IPs. Following is data ...
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2answers
425 views

How to allow UDP broadcast between interfaces on a Cisco ASA 5506-X

I have a CISCO ASA 5506-X with 4 configured interfaces and a set of access-lists etc. It is configured via CLI and is running in routed mode, not transparent. Everything is running well, but now I ...
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1answer
134 views

Can't connect to python server on LAN

So I have this python server which just returns the uppercase sentence which came as a input: from socket import * serverPort = 12000 serverSocket = socket(AF_INET, SOCK_DGRAM) serverSocket.bind(('...
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0answers
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 ...
0
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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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2answers
105 views

How to connect a client behind a NAT router to an Asterisk server behind a NAT router?

I have an asterisk setup on a server. The local IP address is 172.22.9.200 and extenal IP address is 75.45.185.100. My client device is an android phone that is connected to a router and it which ...
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1answer
323 views

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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2answers
89 views

Does UDP includes of source address?

Both UDP and TCP does not include source address, but how does it say UDP IP spoofing is easier than TCP? For example, the following webpage also says about UDP vulnerability. "Unlike TCP, UDP does ...
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1answer
36 views

What does the following UDP connection mean? [closed]

What does the following entry mean? Is that mean someone has connected to the server from this IP or somthing else? Nov 23 15:33:54 www-prod-2 snmpd[1573]: Connection from UDP: [66.151.147.194]:...
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51 views

TCP and UDP ports usually blocked [closed]

Which are TCP and UDP ports most likely to be blocked? I refer especially to the client edge of the network. To start I guess SMTP (25), SIP (5060) for TCP, Traceroute (33434) for UDP.
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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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1answer
17 views

Does STUN work on majority of NATs?

I've been largely ignoring STUN protocol as noise for a while, but I keep encountering it here and there, and I'm wondering of it's general usability. If I understand it right, STUN is only useful if ...
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1answer
55 views

iptables accept specific packet id

I want to allow only packets with a specific id (identification field), for example packets with id=3 are accepted and others dropped. And I want to do the same thing with the offset, so for example ...
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2answers
96 views

Any protocol used by TRACEROUTE ? ICMP or UDP [closed]

Any protocol used by TRACEROUTE : ICMP or UDP or IP ? Or use them all : Encapsulation ?
2
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1answer
123 views

difference between local port range & UDP sending port using dig on Debian nameserver resolver

When i go to my local port range on Debian 7, i can see that my ephemeral port range is: cat /proc/sys/net/ipv4/ip_local_port_range 32768 61000 My /etc/sysctl.conf is empty. Normally that would ...
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0answers
84 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 ...
7
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2answers
402 views

Windows Server 2012 - RDP over UDP not working

I have a Windows Server 2012 (not R2) machine, hosted within Hyper-V virtualization with RD Session Host & RD Gateway installed. It is used to run a desktop GIS application. The performance over ...
0
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0answers
60 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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0answers
344 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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2answers
56 views

SMB / CIFS / Samba Connectionless or Not whilst transfering files?

I have been researching this for a bit, but I have been getting conflicting answers, does samba, from my gatherings, SMB runs on ports TCP & UDP 137-139 & 445. But I have no idea therefore ...
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1answer
611 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 ...
2
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1answer
66 views

I need to REJECT first incoming UDP packet by srcip

Im currently under attack by spoofed udp packets. Every spoofed ip trying to send just 1 udp packet in 30sec. But there is tons of ip. I need to drop first packet. But if same srcip in 30sec sends ...
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1answer
152 views

Blocking ddos string with iptables [duplicate]

I want to ask how do block spefic packet payload? 14:46:35.837759 IP 145.92.16.14.27017 > x.27030: UDP, length 25 0x0000: 4500 0035 44a4 0000 ee11 53ae 915c 100e E..5D.....S..\.. ...
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1answer
49 views

Dest host dont accept UDP when there is no route to source

I have three hosts with following config: Host A: IP:192.168.1.1/24 Host B: IP:192.168.1.2/24 Host C: IP:192.168.3.1/24 Everything happens on CentOS 6, and all interfaces are VLAN tagged (if it ...
0
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1answer
234 views

How to kill a UDP connection from a process Windows Server 2003

I have a program running and it connects to a UDP port to perform multi-casting. I'm trying to simulate a network failure where that process cannot reach the UDP endpoint but everything else still ...