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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UDP sending two strings in a datagram

I'm wondering if its possible to send two strings within one datagram in a UDP packet. Assume I had string 1 with text: unix and string 2 with text: linux. I don't want to merge the strings but keep ...
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1answer
147 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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1answer
683 views

ICMP destination unreachable

I am working on an Arch Linux machine with an ethernet interface eth1. I have created the interface eth1:0 using ifconfig and given it a dummy hardware address (00:01:02:03:04:05). When I send a UDP ...
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1answer
73 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
209 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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1answer
182 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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0answers
6k views

Dumping multicast UDP stream with socat

I am setting up video streaming. In local network, there are two devices streaming video over UDP multicast. One is regular computer with Linux (streaming to 239.220.221.10, port 9200), second one is ...
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0answers
41 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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0answers
269 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 ...
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0answers
208 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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0answers
426 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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0answers
413 views

IPTables dropping UDP packet stream

I have a configuration where UDP packets containing encapsulated DNS data are sent to a KVM instance for processing. The KVM instance sits behind an IPtables firewall which is also doing NAT. The ...
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0answers
776 views

TPROXY for redirecting UDP on arbitrary ports

I want to intercept all UDP traffic leaving tap1. And possibly reply to e.g. DNS-requests. To accomplish this I wrote some python code listening to localhost and use iptables with a rule-set like this:...
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0answers
1k views

Linux bridge blocks UDP packet from tap interfaces

Introduction: I'm working on a 6lowPAN projects of Wireless Sensor Networks. Basically, I have a set of nodes (Contiki OS) which are running on a linux host. Each nodes have its own tap interface ...
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33 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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112 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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180 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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0answers
253 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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159 views

setting up a local VoIP to use as a Wifi Headset

I had this idea of using Wi-fi in a vehicle to connect my cell to the car call handler.Just as it works with bluetooth nowadays. Just to demonstrate that such a thing is possible , i had three Linux ...
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0answers
440 views

Command for finding open ports

On my linux servers I have this alias set: alias ns="sudo lsof -Pi|grep -v ESTABL|grep -v CLOSED|grep -v -e '->' | tr -s ' ' '\t' | awk '{print $3 "\t" $8 "\t" $5 "\t" $9 "\t" $1}'| column -t|...
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0answers
114 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. ...
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19 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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30 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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33 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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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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121 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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0answers
229 views

How to make Network alive but speed low, slow for upload, download?

I have own application written (Python, Java) which does upload/download for streaming. Now in my local office network and home network setup i can't simulate slow/low latency network (as a result i ...
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0answers
765 views

Tools to find OpenVPN UDP packet corruption

Are there Unix tools to troubleshoot UDP packet corruption? I'd like to avoid writing my own... I think ping might report when a packet is corrupted, but it doesn't really seem to have options ...