Stack Exchange Network

Stack Exchange network consists of 174 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

Visit Stack Exchange

Questions tagged [udp]

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

-3
votes
2answers
48 views

How can TCP be used in order to implement DHCP and under which circumstances is this preferable?

I am pretty new to the computer networking studies and was learning about the DHCP protocol. It is implemented based on UDP, as I've gathered, but is there a way for it to be implemented over TCP? ...
0
votes
0answers
24 views

Analyzing packets using wireshark display filter [closed]

!udp && !arp && !tcp && !icmpv6 && !stp && !pim && !ospf what does this display filter do other than filtering out all packets which have any of the ...
0
votes
2answers
18 views

How to know difference between 2 devices connected to the same Wi-Fi hotspot in IPV4?

I am working on a small project to make a client server program to make a connectionless implementation & I want to transmit Information between 2 devices which is connected to the same Wi-Fi ...
4
votes
1answer
66 views

How does the transport layer tell UDP apart from TCP?

So I'm reading Computer Networking: A top down approach (where these images are from) and I was looking at the Transport layer. A generic segment in the transport layer has a pretty simple structure: ...
0
votes
2answers
71 views

Why do UDP connections only require a socket on one endpoint?

I thought for a long time that sockets were defined as an end point of a two way connection, however UDP sockets can be created without the other end making a socket to keep the connection live. What ...
0
votes
1answer
18 views

How is a lost DNS query handled [closed]

If a DNS query gets lost along the way to its destination, is nothing done about it? In my networking class, my lecturer said that DNS runs on UDP. I verified this in Wireshark by doing nslookup for a ...
3
votes
1answer
176 views

How can a UDP Client and a packet sniffer run on the same machine?

In my understanding, if you have a UDP socket client that is bound to a particular port, then a second UDP client on the same machine can't bind to the same port. If this is the case, then how can a ...
1
vote
1answer
85 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
23 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
42 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 ...
3
votes
1answer
55 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
62 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
63 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 ...
6
votes
0answers
142 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 ...
5
votes
3answers
505 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 ...
6
votes
2answers
439 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
184 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
54 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
126 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
80 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
443 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
146 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
125 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 ...
5
votes
1answer
503 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
93 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
80 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 ...
1
vote
2answers
2k 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?
7
votes
3answers
736 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 ...
4
votes
1answer
2k 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.
0
votes
1answer
931 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
310 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
765 views

Does the OSI model support connectionless communication in the transport layer? [closed]

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 ...
1
vote
1answer
380 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
371 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
1k 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 ...
0
votes
5answers
1k 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
414 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
203 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
192 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
3k 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
73 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
2k 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 ...
3
votes
1answer
192 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
786 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
264 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
148 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 ...
0
votes
0answers
212 views

MTU of IPv4-over-IPv6 LTE link

I get only IPv6 address on my mobile phone connected to an LTE network. If I assume that OSI level2 packet size on LTE link is 1428 bytes what would be the max payload size for UDP packets that are ...
0
votes
4answers
699 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
366 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
374 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 ...