User Datagram Protocol (UDP) is defined to make available a datagram mode of packet-switched computer communication in the environment of an interconnected set of computer networks. This protocol assumes that the Internet Protocol (IP) is used as the underlying protocol.

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CentOS: Prioritize UDP traffic based on UDP port number?

We have an two important applications on a CentOS box - one is Syslog, which is using UDP port 514. The other is bind, using UDP port 53. Is there a tuning mechanism that can be used to give higher ...
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27 views

unbind port of crashed program

is there any way to unbind a port that was previously binded by a program that crashed at some time? I don't like to reboot the development-machine every hour.
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iperf3 inconsistent results between Windows and Linux configuration

I have recently started to use Iperf3 and am struggling to comprehend its behavior. My problem stems from the fact that I am getting different results between Linux and Windows OSs. More particularly,...
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1answer
40 views

Iptables Help redirecting specific TCP/UDP Ports to VPN (tun1)

So I have a linux based router and have a vpn client set up to route traffic through the vpn and isp per iptables commands i am attempting to route specific tcp and all udp ports through the vpn only ...
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148 views

What are the requierements to sniff UDP packets in a Wireless Ad-Hoc network?

In a wireless Ad-Hoc network, I have two computers which communicates in UDP together from 192.168.1.3 to 192.168.1.5 I have a third computer (192.168.1.6) which wants to listen to the packets which ...
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23 views

rsyslog doesn't collect logs

I have configured HP 5120 switch to send messages to syslog server: info-center loghost 10.10.84.111 facility local4 on my debian rsyslogd 5.8.11 modified/etc/syslog.conffile: uncommented$...
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25 views

drop rate of the err_queue

In Linux, when requesting the TX timestamp of the sent packets, the err_queue is used to piggy back this information. Is there any way in C to inspect if this queue is full at some Point in time? ...
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1answer
37 views

Unix Domain Socket with VM

Is it a true statement that, shared memory does not work between a host OS and guest OS, but a Unix Domain Socket (specifically udp) can communicate between the two? An in depth explanation would be ...
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1answer
176 views

UDP receive buffer error

We are running opensips SIP proxy in high traffic environment, it's using UDP protocol. We are seeing sometime RX error or overrun error on interface. I have set rmem_max to 16M but still i am seeing ...
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36 views

Measuring latency in a GStreamer pipeline

I'm using a RTP pipeline to stream video from a camera over local network. The pipeline is: camera > h264enc > RTP > UDP > receiver_and_display How can I find out how the latency is composed?
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31 views

minimum time between two consecutive UDP packets

I am interested in developing a C application which sends UDP packets with minimum delay between two consecutive packets. Is it possible to "book" the UDP stack with the NIC hardware from user space ...
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1answer
155 views

How to block broadcast messages (Apple's mDNS traffic)

I am in a network and a user is sending broadcast messages on udp port 5353. Regardless of what that is and what their purpose is, I decided to block all the traffic, so I ran: sudo iptables -A INPUT ...
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1answer
382 views

socat/netcat UDP to TCP

I am trying to bridge a connection between UDP and TCP. The UDP - must listen on port. The TCP - must connect to a server. The purpose of the connection is to control VLC player. I tried netcat and ...
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3answers
8k views

How does netcat know if a UDP port is open?

So I can use this netcat command to check if a UDP port is open: $ nc -vz -u 10.1.0.100 53 Connection to 10.1.0.100 53 port [udp/domain] succeeded! Unlike TCP, UDP is connectionless (fire and ...
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1answer
271 views

Does /proc/net/udp count all drops that occur between ethernet plug and my app?

/proc/net/udp on Linux has a "drops" column: cat /proc/net/udp sl local_address rem_address st tx_queue rx_queue tr tm->when retrnsmt uid timeout inode ref pointer drops 16151: 00000000:...
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4answers
144 views

Mass IP Blocking

I have a game server and someone is spamming it with bots. The SpamBot client makes the handshake with my server using UDP connections. It does this through a list o proxies. Basically, the Spambot ...
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46 views

Netid in ss output is confusing

I'm on an Ubuntu 14.04 x64 machine. I have something running on port 51236 and I want to know whether it's TCP or UDP. So I ran ss -an | grep 51236 and got the following output. tcp ESTAB ...
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35 views

How do I change NAT type for UDP to be more P2P-friendly?

On gateway I do iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE, and on device I have this: $ stun stun.counterpath.net STUN client version 0.96 Primary: Indepndent Mapping, Port Dependent ...
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2answers
937 views

Bash: Permission denied when trying to echo data directly to Network

I am trying to send characters directly to the network stack as explained in this thread. Even when the process work OK under CygWin (Windows), the same lines do fail on Ubuntu v14.04: luis@...
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3answers
220 views

how to get statistics of received packets on a specific udp port

my linux pc has a udp port listening, however, the application does not seem to receive any packets from this port. Is there any tool that I can use to show the number of packets received on this port?...
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29 views

Unable to read a UDP socket from a Python script

I have a machine with Debian 8, 64 bits, updated to the latest version. She is receiving UDP packets through to his local ip. To check the reception of the packages I executed the following command. ...
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4answers
133 views

Is any solution to make interactive TCP/UDP server under Linux?

I need some tool like this one for Linux. I need not a GUI (i.e. GUI/CLI -- this is not so important), but I need to be able to make a server which can listen at any port, receive and send a raw (i.e. ...
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1answer
81 views

iptables DNAT+SNAT: unwanted multiplication of the same udp datagram (and malfunction)

trying to figure out my mistake in the following very simple scenario: |peerA|(Aip:Aport) <--> (Bdev:Bip:Bport)|NatNode|(Cdev:Cip:Cport) <--> (Dip:Dport)| peerD (peer A emits datagrams ...
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1answer
200 views

UDP Port Fowarding: 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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137 views

How to configure linux network socket for incoming broadcast packets

Ok so moving from promiscuous mode to defined code. If my LIDAR is broadcasting from 192.168.0.32 to destination 255.255.255.255 port 8308 UDP datagrams. Then what do I need to set my UDP socket in ...
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123 views

UDP buffer overrun and old datagram clearing

I am reading UDP datagrams on a linux server at 700,000 per second from HDL32 LIDAR system. Interface is ipv4. Sockets are set to SOREUSADDR. I turn on the LIDAR, start up socket program, it started ...
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1answer
42 views

How do I configure my server to stay hidden unless it receives correct password?

The server is supposed to silently ignore any requests (including ping) unless it receives correct credentials with initial request. Nobody else can tell that the host even exists. I am talking about ...
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190 views

How to replace udp packets on the fly

I've used iptables to reroute traffic to netsed like this, but it seems to route the traffic to another location. I've used hexinject like this: hexinject -s -i eth0 -c 1 -f 'arp' | replace '06 04 ...
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3answers
23k views

How do I reserve ports for my application?

How do I reserve a list of ports for my custom applications? To be specific, the product I'm creating has a lot of processes and a lot of intercommunication between them. The problem I'm having is ...
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1answer
398 views

Does the Transmission use only TCP or also UDP?

I will recast the question: Will an opened UDP port accelerate torrenting using Transmission? I opened TCP port and it plainly says open. I don't know what to think. Please take this as a question ...
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3answers
12k views

Multicast UDP not working

Multicast UDP on raspberry pi I haven't narrowed things down enough to know if my issue is because of debian, raspbian specifically, or if I am just missing a something completely. I have a python ...
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1answer
1k views

How can I redirect all UDP traffic from one port to another on BSD / OS X?

On Mac OS X 10.9.5 I am running boot2docker and would like to temporarily forward a non-privileged UDP port 69 to port 69 of the boot2docker virtual machine. Virtualbox only supports forwarding ...
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1answer
328 views

Forwarding a udp socket connection to a range of ip addresses

I have a program which is a udp socket client. I can determine an IP adress to which this program should send. Unfortunately, I configured the computer as Access Point and don't know the address of ...
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1answer
202 views

How do UDP multicast behave on Unix?

A Unix expert told me that ip-multicast uses Ethernet multicast (depends on MAC address to spread) instead of IPv4 multicast. Is this true? Does it depend on the kernel or version?
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1answer
11k views

Is it better to set -j REJECT or -j DROP in iptables?

There's an example of iptables rules on archlinux wiki: # Generated by iptables-save v1.4.18 on Sun Mar 17 14:21:12 2013 *filter :INPUT DROP [0:0] :FORWARD DROP [0:0] :OUTPUT ACCEPT [0:0] :TCP - [0:0]...
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1answer
384 views

A program like nethogs for udp?

I use a good program: nethogs,is like a "top" for tcp traffic someone know something similar for udp? I want to see the udp bandwitch used by program
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2answers
415 views

tcpdump captures network-wide UDP traffic, but not TCP

When observing traffic with sudo tcpdump udp, it behaves like it should: I can see all traffic which is happening in the network, even when the machine which I am using is not involved. However, when ...
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1answer
210 views

Close the neccessary Ports [duplicate]

I am using Linux Mint and I am newbie. Someone is trying to access my computer via my MAC Address and open port. I have some questions: I know that there are different type of port like TCP and UDP. ...
2
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1answer
667 views

nfs mount works for tcp but not over udp

I'm connecting my raspberry pi (raspbmc) with my synology nas. I have 2 mounts 192.168.0.5:/volume1/video /mnt/video nfs udp,intr,noatime,rsize=32768,wsize=32768,nolock,nfsvers=3,async ...
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1answer
476 views

Open UDP Ports; Can I Close Them?

I'm trying to secure my internet browsing. I just reinstalled Xubuntu 14.04 and GUFW firewall. I have 8 UDP ports open. I don't understand why. The software I currently have open are Firefox, GUFW, ...
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259 views

Why doesn't syslog traffic show up in netstat and lsof output?

I've noticed on my CentOS 5.x system that outbound syslog traffic (UDP) doesn't show up in lsof or netstat results. I've even tried stuff like watch -n .1 'netstat -l -u -n --program' to make sure ...
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0answers
282 views

Filter UDP packet in tc filter

Hello I'm trying to limiting the bandwidth on my iperf udp test (iperf -u). I use tc qdisc and class to make some assured rate and ceiling rate for it. However, I don't know what filter I should use ...
2
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1answer
4k views

tftp transfer painfully slow

I am using HPA's tftp server for PXE boot. When I try downloading an image from my tftp server using curl, the transfer rate is less than 3 MB/s, even on my 1Gb network. curl -o initrd.gz tftp://192....
2
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1answer
843 views

enable echo service and linux security loophole issues

in order to enable the echo service we need to add the echo lines as the following example : more /etc/inetd.conf echo stream tcp nowait root internal echo dgram udp wait root ...
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2answers
3k views

Redirect stdin and stdout to ports

I'd like to take a program P that reads from stdin & writes to stdout, but connect it to nc or whatever such that it reads from a certain port and outputs to another port. # The reading is easy, ...
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1answer
134 views

Start a service on a network request (socket activation)

I have a program that under normal activation listens on some port. I don't want the program running continuously. Is there a "quick and dirty" way to wrap the application in a shell script or ...
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215 views

Emulate console by sending data on one UDP port, and receive text from another

Note: I also posted this question on SuperUser, because I'm not sure where it belongs I'm trying to establish a "console-like" connection with a National Instruments cRIO-FRC. It broadcasts its ...
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1answer
539 views

tcpdump and nc with udp

I don't understand the behaviour of netcat. Let's say that I have one host acting as server: [root@localhost tmp]# nc -u -l -p 670 Then I try to connect from a client: root@debian:/tmp# nc -u ...
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437 views

iptables rule to transfer UDP through a SSH tunnel

The problem I have two programs that runs on two distant computers and communicate through a specific protocol. All I know is that this protocol only communicates through UDP and uses the ports 1101 ...
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2answers
630 views

How to find transmission speed?

Two host machine's one as a client and other as a server, i am testing udp load-test in these two machines.Machine Ethernet speed is 100 Mbps but i want to send 30000 packets each of 512 bytes at 1 ...