Questions tagged [udp]

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

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21 views

CISCO: Copy one UDP unicast packet to other destination

I have following scenario: host A and host B are sending to each other unicast UDP packet. I need that same message from host A will arrive also to host C - with new DST address. How to configure my ...
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0answers
15 views

How to send a UDP packet over the Internet? [closed]

I have a program in Rust using std::net that listens for and sends UDP packets to a specified IP address and port. It works fine in my local network, but not over the internet. I've come to understand ...
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1answer
55 views

Is there any other network protocol than tcp/udp that works with ports?

Do you know at least one protocol (any OSI layer) that, like tcp and udp, works with ports ? Thank you
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1answer
14 views

DNS request on google.com. with QTYPE = 0xff returns no entries [closed]

Ive written my own DNS request client but I'm having some interesting behavior. If I send the request with the QTYPE section = 0xff, I get a valid response however with no entries. My Request: 0x70 ...
42
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7answers
15k views

Does UDP do anything at all?

It's my understanding that TCP has logic for ensuring reliable communication, but UDP just naively sends information along the channel set up for it using IP and things in lower layers. Does UDP ...
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1answer
30 views

How might ARP impact the UDP communication and what is a scenario i can reproduce to check/understand it?

I was wondering which impact the ARP protocoll might have on a UDP communication. I am learning for an exam and trying things out with mininet (linux )/ wireshark to understand the dependencys between ...
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2answers
136 views

Is this UDP diagram wrong?

I was just wondering if anyone can tell me why all UDP diagrams I have seen list a request from the server to the client as the first point of communication? Take a look at the following diagram for ...
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3answers
36 views

Is the length header used to indicate the end of a segment?

I was reading a textbook which says the need of length header for UDP: The length field specifies the number of bytes in the UDP segment (header plus data). An explicit length value is needed since ...
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2answers
100 views

How does UDP control the flow of data in file transferring?

I know that transferring files over UDP is possible even though TCP is preferred. My question is how does the server know how much the client can handle or vice versa, or any router in between. TCP ...
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1answer
30 views

How UDP protocol Number is 0x011?

How UDP protocol number is 0x11 when it's supposed to be 0x17 According to ianna website
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2answers
33 views

multicast udp streaming dst and src address assignment

If I am streaming on a host using the internet outside my nat, how is multcast addressing work with respect to streaming for example, if the application outside sends to 224.0.0.1 how is the packet ...
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1answer
26 views

Real time video streaming over TCP [closed]

One of the topics I have been following for quite sometime is real-time streaming. Over the course of my research everyone suggested and says WebRTC (based on UDP) is the only solution to achieve real-...
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1answer
34 views

When port-forwarding, will a port only be listed as OPEN if the service host is actually reachable?

I'm fiddling around in my lab today and attempting to learn more about port-forwarding. I've noticed that when I set up port-forwarding for a given port and run a port scan from outside the network, ...
2
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1answer
69 views

Does UDP perform packet re-ordering at the destination?

User Datagram Protocol is a simpler message-based connectionless protocol. Connectionless protocols do not set up a dedicated end-to-end connection. Communication is achieved by transmitting ...
26
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8answers
15k views

Why does DHCP use UDP and not TCP?

DHCP uses UDP as its transport protocol. DHCP messages that a client sends to a server are sent to well-known port 67 (UDP—Bootstrap Protocol and DHCP). DHCP Messages  that a server sends to a client ...
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2answers
59 views

How does UDP provide continuous sound in VOIP even though segments are discrete?

I would like to know how does UDP achieve continuity in VOIP or in any streaming service.
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1answer
100 views

ports and security

I'm thinking about how the "port" operates for the network connections and tried reading the CCNA cert. guide to understand the details, however, I need to clarify doubts: does occupying all the TCP/...
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4answers
3k views

Why ICMP Destination Port Unreachable error messeage is generated for unreliable UDP packets?

My doubt is why an icmp destination port unreachable error message generated for udp. Why we can't simply discard the udp packet if the destination port is not reachable by saying udp is connection-...
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1answer
375 views

UDP in wifi getting excessively buffered [closed]

We are using a wifi-enabled device that receives a stream of UDP packets (30 per second). It is very important for us to receive these messages without lag, that's why we are using UDP and not TCP ...
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1answer
133 views

How does a DNS response reach a client behind a NAT?

How does a DNS response reach a client behind a NAT? I'm talking about DNS queries using UDP for transport with a server that is not in the same network as the client. Does the NAT correlate the ...
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2answers
52 views

Forcing UDP traffic from specific ports [closed]

Is it possible that all traffic from computer 1 towards computer 2 go thru udp port D of computer 1 and received at udp port B of computer 2. Similarly all traffic from computer 2 towards computer 1 ...
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1answer
216 views

what is the definition of out degree and in degree in computer networks?

in wikipedia we have a good definition for in degree and out degree in a graph: " The degree of a node is the number of connections or edges the node has to other nodes. in-degree is the number of ...
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1answer
98 views

If you're behind a firewall and all the ports are blocked, how is your browser able to access the internet?

I'm behind a router and I'm able to run game servers on my home computer after forwarding ports or using the DMZ feature on the router. However, I still don't understand the underlying technology as ...
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1answer
524 views

Is UDP Hole Punching possible if the network of one peer has multiple external IP addresses?

I've developed an implementation for UDP hole punching that works for most use cases that I've come across. However, one of our offices has a network configuration where we have two ISPs providing us ...
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1answer
138 views

Avoid bottleneck in UDP multicast

The question is that a server is serving a multicast group with UDP. Lets say that its a file server and it will be serving big files (~10GB). Now we have a multicast group with multiple clients. Some ...
28
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7answers
6k views

Why isn't UDP with reliability (implemented at Application layer) a substitute of TCP?

TCP provides reliability at transport layer while UDP does not. So, UDP is fast. But, a protocol at application layer can implement reliable mechanism while using UDP. In this sense, why isn't UDP ...
2
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1answer
426 views

Collect UDP packets lost during iPerf test

I'm testing my network infrastructure where I'm using iPerf and UDP protocol. I'm using the following: On the server side: ubuntu@ip-172-0-1-11:~$ iperf -s -u and the client side: ubuntu@ip-172-2-...
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2answers
2k views

How to measure max bandwidth with Wireshark?

I'm trying to measure the max bandwidth usage of my LAN with Wireshark. I´ve done several packet captures but I don't know how to obtain the max bandwidth usage. Any Idea? Thank you in advance
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1answer
478 views

Weird Wireshark protocol list (eth:ethertype:ip:data where is the “udp”?)

I am capturing incoming and outgoing WAN to LAN data at a particular host on my LAN (i.e., the one actually receiving/sending the data). Sometimes I get anomalous captured frames that are missing the ...
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0answers
122 views

Unable to get NetFlow flow in Cisco CSR1000v on AWS

I'm trying to use NetFlow Traffic Analyzer of SolarWinds or any NetFlow Monitor in my Cisco CSR1000v routers which are deployed on AWS. I am unable to see any NetFlow flows in the NetFlow Traffic ...
2
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1answer
497 views

Setting Destination MAC address for RTP/UDP packets

I have a requirement where I have to send the UDP packet to a destination multicast IPv6 address. In addition to that the packets must also have corresponding destination multicast MAC address set. I ...
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1answer
497 views

How to send data from one PC to another PC over internet? [closed]

I'm basically a developer, and this is the first time i'm trying to develop a chat application over internet without any servers in between. It's easy to send data from PC to server and then to ...
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2answers
380 views

How to calculate traffic in bytes from sFlow datagrams?

I want to approximate network traffic in bytes by writing a sFlow collector that receives sFlow datagrams, parses them, extracts key information only and applies a formula that summarizes the traffic ...
4
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2answers
96 views

Is it correct to assume that ordering of frames at switch level is not important?

My understanding is that if the payload of the frame contains any data that needs to be reassembled, at least for TCP payload, it can be done at the OS level, once all the packets are received and ...
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1answer
361 views

TCP or UDP for Stop & Wait / Go Back N

I'm creating server/client classes for "Stop & Wait" and "Go Back N" (variant of sliding window) protocols, though I'm unsure on whether I should pursue TCP or UDP. From my current understanding I ...
6
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2answers
5k views

Why maximum length of IP, TCP, UDP packet is not suit?

From many tutorials, I get follow knowledge(maybe I'm misunderstood) : maximum of an Ethernet packet is about 1500 bytes. maximum of an IP packet is about 65535 bytes. maximum of a UDP packet is ...
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0answers
26 views

Why maximum length of IP、TCP、UDP packet is not suit? [duplicate]

From many tutorials, I get follow knowledge(maybe I'm misunderstood) : maximum of an Ethernet packet is about 1500bytes. maximum of an IP packet is about 65535bytes. maximum of a UDP packet is 65515 ...
0
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1answer
543 views

How to plot and benchmark UDP response time?

Our application uses UDP protocol in the transport layer. I'm currently filtering the packet trace with the port and then manually checking the RTT by selecting the packet stream and by using " Set ...
-3
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2answers
77 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
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2answers
276 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 ...
5
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1answer
491 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: ...
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2answers
373 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
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1answer
451 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
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1answer
440 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 ...
2
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1answer
201 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 ...
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1answer
63 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 ...
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2answers
82 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
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1answer
868 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
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1answer
290 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 ...
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2answers
1k 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 ...