Questions tagged [udp]

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

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2answers
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Why does IKE use UDP instead of TCP?

Why does IKE use UDP, and handle any retransmission itself? (Larger IKE packets may cause UDP fragmentation and are dropped by some ISPs: IKE over TCP.
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3answers
5k views

Can two different applications bind the same port on a host if they use different protocols?

So my question is quite clear I think. If two applications use different transport layer protocols (e.g. TCP and UDP or something else) can they open the same port number? How does the OS do the ...
3
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1answer
187 views

Satellite Internet Connection - Faster Speed?

I acknowledge the fact that satellite internet maybe quite slow and have high latency. This is generally true for TCP applications like HTTP, FTP etc. If a UDP VPN connection was to be setup between ...
2
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2answers
154 views

Using as many multicast groups as transmitting devices

We have a set of ~40 embedded devices, each one equipped with a wifi module. All the devices are connected to the same wireless network. All the devices send packets to the same "master" computer. ...
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1answer
1k views

HPE 1920-8G-PoE+ multicast filtering

I have a switch HPE 1920-8G-PoE+ that is connected to two computers and two access points: Ubiquiti UniFi AP-Pro n450. The access points receive data from many devices. The two computers send UDP ...
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
7k 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
7k 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
765 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?
13
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3answers
51k 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
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2answers
94 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
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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 ...
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2answers
78 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 ...
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2answers
485 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 ...
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1answer
123 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
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1answer
539 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
295 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/...
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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 ...
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2answers
750 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?
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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 ...
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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 ...
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3answers
769 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?
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4answers
23k 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
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1answer
143 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
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2answers
355 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
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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 ...
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3answers
3k 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 ...
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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 ...
2
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4answers
166 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 ...
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2answers
716 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
81 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
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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
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2answers
346 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
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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 ...
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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
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1answer
236 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
304 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
87 views

When do UDP multicast streams/frames diffuse?

Please consider my network topology: (Machine A0) --- [Switch A] ============ [Switch B] --- (Machine B0) | ...
2
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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 ...
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1answer
768 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 ...
6
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4answers
23k 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? ...
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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 ...
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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 ...
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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
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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 ...
4
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2answers
963 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 ...
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1answer
718 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 ...
2
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1answer
360 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: ...