Questions tagged [udp]

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

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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
1k 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?
9
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4answers
31k 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
149 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
478 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 ...
3
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3answers
4k 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
5k 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
267 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
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2answers
951 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
91 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
2k 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
501 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 ...
3
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2answers
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 ...
3
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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
268 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
396 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 ...
2
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2answers
92 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 ...
-1
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1answer
966 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 ...
12
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6answers
37k 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? ...
4
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3answers
12k 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 ...
4
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1answer
4k 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
129 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 ...
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3answers
10k 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 ...
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2answers
1k 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
1k 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
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1answer
2k 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
1k 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
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1answer
1k 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?
4
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1answer
8k 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
5k 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?
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2answers
3k 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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3answers
7k 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 ...
4
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1answer
9k views

UDP Port Forwarding Range

We just purchased a cisco 3825 router running IOS 15.1. The slice of the topology in question is as follows: RTP (8000-20000) RTP (8000-20000) 192.168.2.1 <-------------->...
3
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3answers
25k views

Sending generic UDP traffic for Network Simulation

I need to test an application which drops a user-specified percentage of packets. Right now, it will drop any packet type which I can easily verify by sending pings and observing the ICMP messages in ...
9
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3answers
18k views

Traceroute Over TCP vs UDP

For what purpose would one wish to send traceroute over TCP rather than UDP? What advantages/disadvantages are there in doing so? I know that traceroute normally uses UDP ICMP "echo" packets while ...

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