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Questions tagged [udp]

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

2
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2answers
2k views

Multicast doesn't get forwarded correctly [closed]

I have a problem with UDP-Multicast with Kubernetes: I have to Kubernetes-Nodes each of them running a pod: Kubernetes-Node-1: - eth0: 192.168.0.2/24 - docker0: 10.1.1.1/24 Pod1 on Kubernetes-...
3
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3answers
6k views

Why do i only see QUIC and not UDP during capture in wireshark?

I've been using wireshark and noticed that I no longer see UDP but QUIC, why is this the case?
18
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3answers
6k views

What do TCP/UDP add to “raw ip”?

I know that both TCP and UDP are built on top of IP, and I know the differences between TCP & UDP, but I'm confused about what exactly "raw ip" is. Would it be fair to say that TCP & UDP both ...
2
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3answers
739 views

Sending raw IP packets over UDP

Can we send raw IP packets over UDP? What are raw IP Packets? UDP is a connectionless and unreliable protocol, is it?
12
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3answers
46k views

How to verify that a UDP port is open? [closed]

I have here a dilemma. I have a device that communicates to another remote device but there is a firewall between them. It's a UDP connection, so TCP utilities don't work to test if the specific port ...
2
votes
1answer
58 views

Could long sequences of consecutive zeros cause Ethernet link problems?

I am in the process of debugging an Ethernet communication issue. Basically using Wireshark to monitor the source data the stream was intermittent when the cable was removed and subsequently ...
2
votes
2answers
3k views

Where are UDP packets lost during iPerf test?

I'm testing a 802.11 wireless link using iPerf and the UDP protocol. Using the -b command at the client, I can set the bandwidth to an arbitrary number (e.g. 1 Gbps) that's much higher than the link ...
2
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2answers
77 views

Performance of a socket [closed]

What is the difference between the following scenario's. And is there any performance differ due to this. Consider a server provide 5 services like web, mail, file, app and ssh : Each service and ...
1
vote
2answers
473 views

Connecting to a remote computer over cell network with flaky connection using VPN over UDP? [closed]

I was wondering if someone could provide some networking guidance. Any ideas/suggestions are welcome. I am trying to figure out how to reliably connect from my office computer to a computer on-board ...
5
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1answer
1k views

What is the reason for the different order of the Source and Destination in a L2 header?

A TCP/UDP header (Layer 4) lists the Source Port, then the Destination Port: An IP header (Layer 3) lists the Source IP, then the Destination IP: An Ethernet header (L2) and a WiFi Header (L2) lists ...
1
vote
1answer
121 views

UDP protocol that can't be used for DDOS?

I'm designing a protocol similar to the DNS protocol but that may return more data. I have the option to use UDP or TCP. UDP is attractive because it is stateless, but it can also be used for DDOS. ...
1
vote
1answer
520 views

why does my openVPN client work over udp, given that i am behind several firewalls [closed]

this is been puzzling me for months now, i tried to google this, but results are often irrelevant, like questions about why is something not working for someone and how to deal with firewall problems. ...
2
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1answer
291 views

Linux routing: routing between 2 local interfaces depends on source address? [closed]

The setup is this: The linux system (debian 7 as a VBox guest) has the following interfaces: $ ip addr 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue state UNKNOWN link/...
2
votes
3answers
134 views

Is there a way to build a functional (sub)network with devices that have the same MAC Address?

I have a series of modules (similar to a RPi) that run a Linux flavor each having an Ethernet NIC. I have 4 of these and I want to connect them to a switch to be able to send UDP packets to each one ...
0
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2answers
688 views

Real time traffic explanation

What is the difference between Best effort traffic and Real time traffic? Is TCP means best effort traffic and UDP means real time traffic? Or anything else?
1
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2answers
2k views

Very slow TCP speed and throughtput in contast to UDP

I have been monitoring a 1 Gbps OM2 fiber connection to one switch we have with Smokeping... There seems to be an avg loss of 3-4% for a few days now.. Started troubleshooting using iperf, having set ...
2
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3answers
1k views

TCP and UDP port reservation difference and limits [closed]

Considering TCP: When I create a server socket I reserve a TCP port from SO. When a client connects to my server my SO reserves a TCP port different to exchange data. Is there a limit to the number ...
4
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3answers
752 views

port numbers for TCP and UDP

Why do we need both source and destination port numbers in transport layer protocols such as TCP or UDP? What is the purpose for having both?
8
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4answers
22k views

How to know whether a protocol uses TCP or UDP

Well I know that might sound a stupid question and I believe that the most proper answer will be like I will be able to tell as my experience builds up and I learn more and more about the protocols. ...
4
votes
1answer
141 views

Copying bytes from Wireshark

Should it be possible for someone to export the binary payload (say from a UDP packet) captured from Wireshark and later send this stream as a "valid" UDP packet? Longer story: I've captured a DNS ...
5
votes
2answers
344 views

Does the NAT source UDP port depend only on src ip/port?

Does the NAT UDP port depend only on src ip/port? Suppose I have a two networks connected via a NAT/router using Source NAT. PC A (192.168.0.2) in Network A (with router 192.168.0.1) sends a UDP ...
0
votes
1answer
34 views

Website Forwarder not Forwarding— but is? [closed]

This problem might be a lot simpler than you guys are used to, with an equally simple solution but I'm just not seeing it. So we have a redirect site called: delphonbenefits.com which redirects to ...
3
votes
3answers
2k views

DNS Resolution:<Backwards IP Address>.in-addr.arpa [closed]

Can somebody please explain whats going on here? localuser@localhost:~$ host 127.0.0.1 1.0.0.127.in-addr.arpa domain name pointer localhost. What's up with the IP address being resolved ...
3
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2answers
4k views

Should I increase the timeout value for UDP on our VPN router-device?

We have a SonicWALL NSA 2400. We have numerous (100+) personnel in different offices in different physical locations that establish VPN sessions successfully every day. Some of these client computers ...
1
vote
4answers
156 views

Multi-part: TCP, UDP, SSL and Data Pipes

As I understand, TCP packets in a TCP session can take any path in the world to their destination, the path each takes depends on the routing tables of the routers it passes through, resulting in some ...
1
vote
2answers
673 views

Why do routers (and router firewalls) go through so much effort to make peer-to-peer difficult? [closed]

It is not uncommon for large routers to have unpredictable, random port allocation (which cripples UDP hole punching by making port prediction impossible) and for firewalls (not the software firewall ...
0
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1answer
78 views

Streaming data with different sampling rates and data types [closed]

I want to build a server/client application, where a smartphone streams real-time data from the device to a stationary computer. They are connected directly via WiFi. The streamed data shall include ...
2
votes
1answer
1k views

Streaming ip camera to many client monitor, udp/rtsp

I need to broadcast an ipcamera to many different spot. Now the system is alredy working but every client read the streaming directly via network. I want to reduce the traffic by sending just one "...
2
votes
2answers
344 views

single connection over multiple internet connections

Hi not sure where to ask this thought this would be the best place, i was just wondering if it was at all possible to have a single connection get the benefit of multiple internet connections. For ...
2
votes
1answer
1k views

How are UDP source ports mapped on a NAT?

Here is an example use case; I am curious to see how this is suppose to work and why: Someone has a NAT router from their ISP. Behind the router are 2 PCs running Linux and using ntpd. ntpd sends ...
2
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2answers
1k views

If I UDP multicast to 10 listeners in a multicast group, will my upload bandwidth usage increase by 10 fold?

My internet has an upload limit of 1 Mb/s. If I am in a UDP multicast group with 10 people and I send something to the group at a rate of .1 Mb/s, will my upload rate be 0.1 Mb/s or 1.0 Mb/s? Assume ...
7
votes
1answer
230 views

Throttling among Data Centers

In general, links among data centers are shared (having shared network infrastructure). Thus, I can't detect the available bandwidth in between two data centers that may vary every while and through ...
2
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2answers
299 views

'Copying' UDP Broadcast to Specific IP Address?

I'm very inexperienced in networking, so please pardon any idiocy. We are mechanical engineers trying to connect weird hardware that talks on Ethernet. We have a device A that can only send UDP ...
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2answers
82 views

When do UDP multicast streams/frames diffuse?

Please consider my network topology: (Machine A0) --- [Switch A] ============ [Switch B] --- (Machine B0) | ...
1
vote
1answer
2k views

Is a brute force UDP hole punch possible if both external IPs, and both internal ports are known to each client?

So I was just reading about hole punch techniques for UDP and TCP. I read that TCP hole punch can easily be accomplished if a UDP connection has already been established. So here is my theoretical ...
-1
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1answer
741 views

Wireshark time to live pattern question

what pattern does ttl usually follows? working with a task where the ttl increments by 1 for every 3 packets. In the other task the ttl does not have any clear pattern. Info: I am doing traceroute ...
5
votes
4answers
22k views

Is a DHCP offer packet a broadcast or unicast?

DHCP OFFER is a layer3 broadcast because the server don't know client Ip, but server knows the client mac address. So how it would be the broadcast? If anyone ask me about this? how should I answer? ...
2
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3answers
6k views

how to make udp reliable

In a job interview i had faced a question that In my company we always use udp because it is very much fast. and we have reliability also. can u answer how? without adding so much overhead to the udp ...
3
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1answer
3k views

Is it possible to have same multicast group members listening on different port numbers?

Let's say I have a multicast group 239.0.0.1. If A and B are members of this group and listening on port 6000, I can send data to (239.0.0.1, 6000) and both A and B will receive. Now, if A is ...
1
vote
1answer
124 views

Flow and error control

TCP is able to do flow and error control, is it a resulting consequence of using virtual circuit to send pacquets ? Would it be possible to do error end flow control in datagram mode ? For e.g with ...
5
votes
3answers
9k views

Packet forwarding in TCP vs UDP

Recently I had a discussion about differences between TCP and UDP, and the other person insisted that there's a difference in packet forwarding: The packets in a TCP connection follow an established ...
3
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2answers
959 views

Difference between UDP and TCP

http://www.dummies.com/how-to/content/the-tcpip-networking-protocol-suite.html I was reading the difference between the two, and in the example of TCP: For example, when a user running a Web browser ...
1
vote
1answer
701 views

UDP checksum - explaining the method of adding two 16 bit integers?

Can somebody explain to me how to do the UDP checksum of two 16 bit integers. While using the wraparound, sum and checksum? here an example... add these two 16 bit integers 1110011001100110 ...
8
votes
1answer
1k views

UDP hole punching NAT port

I just read an article about the process of "punching holes" with the UDP protocol. I understand how it's done, but I have one last question to clear up things. We have the rendezvous server and ...
1
vote
1answer
329 views

IPsec, how to differentiate TCP and UDP

I read a little bit on the Wikipedia IPsec page. I was intrigued by: IPsec is an end-to-end security scheme operating in the Internet Layer of the Internet Protocol Suite I understand this as: ...
5
votes
1answer
900 views

why RIP sending only maximum of 512 bytes of data

When RIP router sends update to routers, why it is limited to use only 512 bytes of UDP data. Why not more than that, even when it has a 1500 byte MTU. How is the maximum of 512 bytes determined?
3
votes
1answer
7k views

VXLAN: how receiver knows that the received packet is VXLAN-encapsulated?

I'm trying to understand how a receiver knows that the received packet is a VXLAN-encapsulated. Looking at the VXLAN RFC, I can't see anything specific that defines that the packet contains VXLAN ...
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2answers
3k views

Why No Source and Destination IPs in UDP Datagram?

In literature, I see UDP datagram format as following: I cannot understand why it does not include source and destination IP addresses?
3
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2answers
2k views

When is TFTP used? [closed]

It seems like a strange idea to transfer files using a connectionless protocol - so in what situation would you not care about if the entire file is delivered or not? I read somewhere that TFTP is ...
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vote
3answers
6k views

Does TCP use Virtual Circuit Model?

First some information: In virtual circuit model ( which is in the Network Layer ) there are three phases: 1) Connection establishment => In this step a path is chosen. Let's simply say, use ...