Questions tagged [udp]

For questions about User Datagram Protocol, a Transport Layer protocol.

Filter by
Sorted by
Tagged with
2
votes
1answer
265 views

Is there any video streaming online service that actually uses UDP?

We usually hear that UDP is used with data with which a few packets loss/out-of-order can be tolerated like video streaming. And the instructor typically goes on saying "so if you lose a few ...
1
vote
1answer
76 views

Question about output of 'lsof -i' and UDP being connectionless

I'v got a simple setup: Server (IP 10.0.0.33) listening on port 7770 using the command: $ netcat -lup 7770 And a client (IP 10.0.0.2) that communicates with the server using: $ nc -u 10.0.0.33 ...
3
votes
2answers
83 views

How could a response be sent to the requestor without requestor's address?

I'm reading this talking about the differences between two fire-and-forget message (for example, under UDP) and a request-response communication (for example, under TCP). I came across this: The ...
4
votes
1answer
1k views

Packet with wrong source MAC address

When I send a UDP packet with wrong source MAC address but with right source IP address, assuming a reply is sent, will I get the reply because I have right source IP address, or I will not get the ...
0
votes
1answer
310 views

Wireshark udp checksum errorI

I sniffing udp communication with 2 instance of wireshark , 1: 2.0.0 2: 2.2.1 . In version 2.0.0 I get valid udp.checksum , but with 2.2.1 I always get udp checksum = 0000 . Why is that? those ...
1
vote
2answers
2k views

Why is there a difference on the amount of data transferred during a UDP iperf measurement?

I have the following result from a UDP throughput test as measured by iperf3 $ iperf3 -u -t 10 -c 192.168.1.2 -b 100M -V iperf 3.6+ Linux pi-raspberry1 4.4.38-v7+ #938 SMP Thu Dec 15 15:22:21 GMT ...
9
votes
2answers
599 views

How to control unwanted UDP traffic (Broadcast & Multicast) on Cisco Router 2911?

Please suggest, we are getting UDP traffic either broadcast or multicast in router 2911 which cause 95%+ utilisation of the router. And we got error in link and business impact due to this. Company ...
8
votes
4answers
9k views

Why is a TCP Socket identified by a 4 tuple?

Newbie to networking here. I'm reading the Computer Networking (3rd edition) book, and in section 3.2 they are discussing multiplexing / demultiplexing for both UDP and TCP. In the UDP protocol, a ...
8
votes
2answers
3k views

How does NAT work with incoming UDP packets from unknown IP

Apologies in advance for the relatively noob question and if this is off topic here ( I am not sure...) The situation is that I have a UDP client and server bound to the same port. My understanding ...
2
votes
1answer
612 views

How IP datagram know its upper layer protocol?

Hi I'm a newbie in networking, I just want to know how IP datagram know its upper layer protocol is TCP or UDP? I know there is protocol field inside the IP datagram header that can tell the layer ...
1
vote
2answers
2k views

How does the server know how to respond to a UDP packet? [closed]

As far as I know, UDP ports and OS sockets are mapped only by the (local port, local address) pair. In other words, the receiver side's OS does not keep a state of (remote port, remote address) pair (...
1
vote
1answer
1k views

User Datagram Protocol (UDP) protocol can error control?

UDP can congestion control? UDP can flow control? UDP have some error correction mechanism?
1
vote
1answer
131 views

HP MSR2004 router is not processing udp through nat

I set up a new HP MSR2004 router for a corporate network. The network uses an internal private net and has one static public ip address. Surfing the web and all tcp related things seem to work fine. ...
6
votes
3answers
827 views

Is UDP Usage in Routing Information Protocol (RIP) a Secure Practice?

I know that UDP is a connectionless transport layer protocol. Since it is easy to fake your source IP and source Port in your headers, what keeps anyone from poisoning routing tables via RIP? It seems ...
3
votes
1answer
177 views

rate-limit dns queries on HP procurve 8212zl

I had ast week the situation that a user accidentally got our DNS server to its knees by sending over 270K DNS queries to our dnsmasq. I was looking for a reliable method to prevent this Happening in ...
0
votes
1answer
264 views

NS2 program specifications questions

I am using the Network Simulator NS2 program (https://www.isi.edu/nsnam/ns/) in order to simulate a simple network topology with 1 UDP agent and 1 CBR Application Traffic sending data from a node over ...
7
votes
1answer
701 views

How does UDP NAT Know When To Remove The Rule

So say you are a user behind a NAT/router on an internal network. You begin sending UDP data to an internet-facing server. The packet hits your router, it inserts an entry to allow returning packets ...
0
votes
1answer
200 views

Udp broadcasting for communicate with a device who has the same IP address , is it possible?

I was thinking about broadcasting in an ad-hoc local area network, then i asked me a question.Assuming that this LAN is made of 2 pc, if this pc have the same IP address, Can i send udp packet from ...
2
votes
2answers
198 views

UDP packets vs two parallel gateways running NAT

I‘m writing an application that sends information, using UDP packets, to the server on the internet and then receives data same way. It seems to work fine from behind NAT but I’m wondering about more ...
4
votes
2answers
7k views

NAT and UDP problems

I have a question regarding NAT, UDP and TCP. Given a standard NAT server, is it a problem for it that UDP is connectionless? If so, why? And does TCP or QUIC solve this problem?
6
votes
3answers
984 views

Does a switch always get a MAC address from a PC?

I was wondering if there is a possibility that a switch won't get the needed MAC address to it's CAM. For example, if the used protocol is UDP, where the sender doesn't need an answer back from the ...
8
votes
1answer
8k views

How `UDP Hole Punching` Works?

Can anyone explain how UDP hole punching works in a simple way? I know how NAT and PAT works, but can't get a clear idea about UDP hole punching.
1
vote
1answer
2k views

Does Cisco-IPSLA work with Huawei-NQA?

I want to monitor udp-jitter using IP SLA (Cisco Router). The Destination Router was Huawei Router. I'm not sure whether Huawei Router doesn't support IP SLA responder. Is there anyway to use NQA with ...
0
votes
1answer
534 views

How to measure latency and udp-jitter from the end-server [closed]

Is there anyway to monitor a latency and jitter from SLA Router to EndClient(Linux Server). I have tried to use IP SLA with UDP Jitter but it didn't work. Diagram SLA-Router -------> Linux ...
0
votes
3answers
2k views

Does the OSI model support connectionless communication in the transport layer?

In section 7.4.4.1.2 of ISO/IEC 7498-1:1994(E) it begins with: In connectionless-mode, the Transport Layer provides the following functions to support connectionless-mode transmission: But many web ...
1
vote
1answer
598 views

How does the UDP Checksum tell me if my data has changed?

currently I am having a Computer Networking cours and I am reading "Computer Networking a Top-Down Approach" At this point I am reading the Transport Layer part. And I have read about the checksum ...
1
vote
1answer
814 views

UDP checksum calculation on improperly padded packets

Suppose I'm receiving IPv4 UDP packets whose payload is less than 18 octets, so when they are transmitted over Ethernet they have some trailing padding. Between the packets' source and my receiver ...
3
votes
1answer
4k views

Traceroute UDP port question

I know, that traceroute uses UDP, and for destination port it starts with 33434. Then, with each next hop it increments the destination port number by 1. The questions is: why does traceroute need to ...
2
votes
5answers
3k views

Why is TCP/IP popular?

I understand that TCP/IP protocol is widely used as it is more secure (the third handshake). But, is there any other reason why TCP/IP is more popular than UDP?
2
votes
2answers
2k views

Why do open ports give no response in networking?

Nmap places ports in open|filtered state when it is unable to determine whether a port is open or filtered. This occurs for scan types in which open ports give no response. The lack of response could ...
1
vote
1answer
388 views

Does an EIM-NAT work across both UDP and TCP?

I've read RFC 4787, 5382 and 5128 and I just need a bit of clarification. Assume a NAT has Endpoint Independent Mapping behavior for both UDP and TCP. Although I understand that if a machine would ...
0
votes
2answers
643 views

Traceroute program that does not rely on ICMP echo requests?

Is there any Traceroute program that does not rely on ICMP echo requests? The question is very straight forward, and I can't get into more details at the moment.
2
votes
1answer
6k views

Iperf results on UDP Bandwidth

I am currently testing iperf with a view to automating some testing servers for our company. To do this I am using an iperf server in the cloud which is well connected and is only 5 hops away from ...
0
votes
2answers
93 views

Limiting NIC speed leads to better video quality

I have two workstations A and B connected to the same L3 switch at 1Gbps. Workstation A generates an MPEG2-TS UDP video stream at 10Mbps data rate. Workstation B receives this stream correctly. The ...
6
votes
5answers
4k views

Is rerouting possible in UDP?

So I am trying to understand routing for TCP and UDP segments. I have a couple of things that I am confused about: In TCP, is there any specification on how many packets would be dropped before a ...
4
votes
1answer
356 views

802.11 multicast buffering due to random back-off mechanism

I am trying to achieve periodic multicast with WAP (Wireless Access Point) [basically trying to stream real time audio data to multiple devices]. The regularity in the interval between successive UDP ...
1
vote
2answers
2k views

UDP Sessions and Ephemeral Port Selection

I would like to ask community to help me finding answers to the following questions: According to RFC 6056 an operating system should pseudo-randomly select ephemeral ports for each transport layer ...
1
vote
1answer
375 views

Header checksum and pseudo IP header

In IP header we have header checksum field which is calculated at every hop because some of the fields in IP header like TTL changes in every hop. In TCP we calculate checksum on pseudo IP header + ...
0
votes
2answers
296 views

Hardware Implementation of Ports

What is the hardware implementation of a port and/or network socket? I understand that, at the lowest level, x86 uses opcodes such as IN and OUT when the data resulting from the instruction execution ...
1
vote
2answers
3k views

Why traffic shape/police ingress traffic?

Pardon me for my ignorance. I have not tried QoS nor traffic shaping/policing before. I have been pondering on whether can/why would we want to shape/police ingress traffic if you have no control ...
0
votes
4answers
1k views

Why the combination of “TCP/IP” is more popular than “UDP/IP” [closed]

According to 7 Layers of the OSI Model, IP is located at layer 3 (Network), while TCP and UDP are located on layer 4 (Transport). Just for the sake of curiosity, why the combination of "TCP/IP" term ...
0
votes
1answer
616 views

Where in PCAP-NG does the Source/Destination IP address information reside?

I'm studying the pcapng file format, and I know that when wireshark reads a pcapng file, it tells you all sorts of information. I've been reading the pcap-ng format and I don't see anywhere in pcapng ...
1
vote
2answers
788 views

port 8820 - what is it?

I need to write a code, which communicates between 2 computers. I saw many people use port 8820 in their code when they want to communicate between computers. I know the term port but What is port ...
1
vote
1answer
4k views

UDP Over Ethernet - Where exactly and in what order will the UDP information show up in the payload of my Ethernet frame?

I need to capture UDP information coming to me via an Ethernet frame. I have a point to point connection by fiber with 1000BASE-X Ethernet. The information coming to me is in GMII format; which is ...
2
votes
1answer
282 views

Is it possible to successfully send a spoofed UDP header with a completely unrelated source IP?

I've read that many networks use ingress/egress filtering to eliminate the number of spoofed UDP packets sent and received by their network. Given that network provides have been much more diligent ...
1
vote
1answer
318 views

Client security using UDP

Introduction I am currently trying to build up a networking layer for Unity from scratch. Currently I am testing the communication via UDP using Node.js for the server and the client. However I guess ...
5
votes
2answers
691 views

Does implementing some level of reliability in UDP packets defeat its purpose over using TCP?

Considering UDP packets can get lost or arrive late to their target destination, does it make more sense to: Use a TCP socket for important messages & events (ex: in a game where a player gets ...
2
votes
3answers
808 views

How to differentiate between UDP traceroute packet and the normal data traffic?

I am a programmer and we can filter out the packets in the router to manipulate the IP or MPLS headers. My question is there any way to distinguish between UDP 1 byte traceroute data vs user traffic ...
1
vote
1answer
3k views

Is there any way a UDP checksum could be inconclusive of error detection?

If I am receiving data through UDP, with a checksum that checks out to show no data loss, is there a possibility that the checksum missed some errors. My data transmitted is split into 24-bits chunks ...
2
votes
4answers
359 views

Tcp reliabity handled at hardware level?

At work we are moving from a TCP to a UDP protocol for a kind of 3D engine because we have 1s hang when a packet is lost. Since our engine is not designed to handle packet loss nor out of order ...