Questions tagged [tcp]

For questions about Transmission Control Protocol (TCP), a transport protocol used to encapsulate data across a network for reliable communication.

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Does my peer to peer network acrhitecure makes sense? [closed]

Basically node has a TCP listener and waits for incoming connections, when one does connect it does handshake and stuff.... Other then TCP listener node has TCP client that connects to the TCP ...
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HTTP and TCP relationship

I always wondered how HTTP knows when it has enough TCP segments in order to process a request or response. Can someone give me more information about the process? Thanks.
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In HTTP2, as it use same TCP connection for bidirectional streaming, why does not messages collide? [closed]

I don't have a formal computer science background so this question might seem elementary to some people. I have elementary to networking myself. This curiosity came to my mind when I was learning gRPC....
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Reasons for tcp session break and how to check? [closed]

In advance, I would like to thank you for taking the time to read it. I need the experience of colleagues. I'm having a problem with broken TCP segmentation and would like to find the reasons that ...
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TCP segment with flags ACK, PSH, URG

Can a TCP data segment with a 1 byte length have, at the same time, the flags ACK, PSH, URG set ? Is it conform or not to the TCP protocol ? Thank you.
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How Does A Layer 2 Switch Differentiate Between Different Networks?

I know that different IP-based networks can be connected to the same layer-2 switch. and I know each network's nodes can communicate just fine, however, no normal traffic can occur between two nodes ...
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How to change the source port without interrupt the TCP connection? [closed]

I use TCP socket to connect a client(source) and a server(destination), the connection has been established. Now the project need to change the source port without interrupt the connection. Both ...
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UDP supports multicasting and broadcasting in transport layer or application layer?

We know that UDP does supports multicasting and broadcasting. My question is which layer "UDP supports multicasting and broadcasting"? Is it transport layer or application layer? We know ...
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1 answer
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What is difference between socket connection and TCP connection?

We know TCP socket is port numbers and IP addresses. Is TCP socket connection is 3-way handshake:the SYN packet, the SYN-ACK packet, and the ACK packet? Is TCP socket connection follows TCP stack? And ...
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How IP packet's payload bigger than the whole former PDU (segment)? [duplicate]

As far as I know: File is too big ---> Fourth layer (TCP or UDP) divide it to a multiple segments ---> Then each segment encapsulated separately into a packet. What means if I have 10 segments, ...
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Inherent flaw in stateless firewalls?

I am but a lowly (software) developer dabbling with setting up a network in AWS and am having trouble understanding the fundamentals of stateless firewalls, or Network ACLs as they're also referred to ...
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Why is Packet Size Limited?

I was reading: this answer to "Maximum packet size for a TCP connection", where it says: The absolute limitation on TCP packet size is 64K (65535 bytes), but in practicality this is far ...
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Why need Ack flag if we already have ack number in TCP

If we have ack number so from there we can trace that how many bytes are received and which byte is need next so then what is the use of Ack flag there?
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Is there any other scenario of TCP segment window size equal 0?

Is there any other scenario of window size equal 0? in my impression, if the window_size == 0, there have two cases: 1.the TCP acceptance area is full, then send window_size = 0 2.send RST package, ...
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How n level come to know the n+1 level contents?

Suppose in application layer is running some application. And application has respective source port number and destination port number. And know that n layer has no authentication to know about n+1 ...
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LLC layer: what's the multiplexing principle? [duplicate]

I wonder what is concretly the multiplexing principle done by the LLC layer. Can you please explain the principle with practicle example ? Many thanks for your help
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Does window size in tcp header include tcp header size?

Let's say a TCP segments has in the field of "window size" = 1400 bytes. Does that mean that we can send 1400 bytes counted in tcp segments = TCP headers + data or it does specify only ...
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TCP behaviour when a ACK is never received

What is the behaviour of TCP if ACK is lost for ever. Will retransmission happen for ever or will the connection be reset ? Lets say A is TCP-server and B is TCP-Client. If the Server, A, fails ...
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What will be the sequence number consumed by FIN flag? [duplicate]

In the connection termination phase, suppose the FIN segment from the client-side contains data ranging from sequence no 100 to 200, So will the ACK no from the server start from 201 or 202? Will the ...
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What will happen if a sender use TCP and receiver uses UDP?

I am new to networking and was studying about TCP and UDP. One question came to my mind that what will happen if a sender uses TCP and receiver uses UDP for the communication.
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Latency between a churn and congestion event triggered in the TCP code

I am analyzing the time it takes between a churn occurring in the network (e.x. that causes packet drops or delays) and when the congestion event handling codes are triggered in the TCP kernel in the ...
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Can UDP traffic be transmitted over TCP ports on OpenVpn to avoid the TCP meltdown

I understand the TCP meltdown problem is associated with overcompensation from errors and incorrect sequencing when arriving the the receiver end. OpenVpn connections are recommended to use the UDP ...
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How can I use scapy to make a port appear open-device behind NAT?

This has been asked in stack overflow like 7 years back. I don't see the correct answer there. Is there any way to do this? While this packet keeps on being transmitting, doesn't the other end see the ...
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TCP payload error handling at the application layer [closed]

How are errors in the payload of TCP packets handled by the receiving application? The packet is received but for various reasons (including sending erroneous packets on purpose) the payload of the ...
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Hosting a website using dynamic public IP: What if the ISP did not assign any port forwarding? [closed]

Let's just say that I am a peasant that can only avail of a typical Dynamic Public IP address from my ISP. Just for the sake of example, let's say have the following: Domain Name: experiment626....
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Why loss of first Syn + Ack from the server will not establish a connection? [duplicate]

In TCP 3-way handshake, 3 segments will be sent (SYN, SYN ACK, ACK). What if loss of syn+ack from the server will not establish a connection? What if the third segment(ACK) is lost? Is the sender ...
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Why sender window or congestion window size becomes 2^n mss after nRTT in slow start mechanism?

I seen everywhere in slow start mechanism if initial sender size denoted by cwnd= 1mss , then after 1 RTT cwnd becomes = 2 mss, and after 2 RTT cwnd becomes = 4 mss and so on. My question is why ...
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Is really TCP takes 3*RTT time to make a connection?

TCP takes 3 RTT time I have read from one stack overflow answer to make a connection with server. We know that TCP takes triple (Syn, Syn/Ack, Ack) to make a connection by 3-way handshake with server....
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2 answers
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Why client will send a RESET when it is closed state?

Suppose I have an TCP state transition diagram. And assume that the last ACK is lost. Then, B will think that A did not receive the FIN and will retransmit the FIN. From B point of view this is the ...
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How a single BGP-process establishes sessions with neighbours in different VRFs?

In VRF-lite solution scenario, when BGP session is established between CE connected to a VRF in PE. The BGP process or in other words TCP server, is listening on port 179(default) for incoming BGP ...
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Why in the TCP/IP model the link & physical are one?

I'm currently learning about the OSI model and the TCP/IP models, and I was wondering: Why in the TCP/IP model the physical layer and the data link layer are combined? I'll state how I understand the ...
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Why the pseudo-header is not transmitted with the UDP datagram?

I have read from E. Comer - Internetworking with TCP/IP 4th edition that "The purpose of using a pseudo-header is to verify that the UDP datagram has reached its correct destination. The key to ...
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UDP checksum calculation for checksum results in the value zero

I read UDP checksum from Wikipedia that "If the checksum calculation results in the value zero (all 16 bits 0) it should be sent as the one's complement (all 1s) as a zero-value checksum ...
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How UDP checksum get IP address to make pseudo header in transport layer?

We know that UDP checksum's pseudo header contains the most important parts of the IP header, that is, source and destination address, protocol number and data length. I hope that the concept of IP ...
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Why router can't be used for converting different model of network but gateway can do this?

We know that Router can't be used for converting different model (e.g OSI model to TCP/IP or TCP/IP model to OSI) of network. It isn't a multiprotocol converter. But gateway is a highly sophisticated ...
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Maximum value of file that can be sent [closed]

this is the following question I have encountered in school. There is a file of X bytes that needs to be transferred from Host A to Host B. The MSS is 10 bytes. What is the maximum value of X such ...
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1 vote
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How is UDP used in multimedia system inspite of being connectionless

We know that UDP does not care about segment (packet) in-order and their arrival on the destination.Then how on YouTube or VoIP (skype) are we able to stream videos? If a packets is lost (doesn't ...
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Is it possible for TCP can accept out of order segments?

TCP is connection-oriented protocol whereas IP isn't connection-oriented protocol. Any packets before sending into transport layer sorted operation must have been done in network layer. That's why we ...
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Why is bandwith-delay product the maximum in-flight datas in TCP? [duplicate]

I have often read, for example https://en.wikipedia.org/wiki/Bandwidth-delay_product that: The result, an amount of data measured in bits (or bytes), is equivalent to the maximum amount of data on ...
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Are duplicate sequence numbers from different TCP-connections possible?

While learning about Sequence and Acknowledgment numbers one thing bugged me. I wasn't able to rule out for myself if the following scenario in which Host A sends data to Host B by using some ...
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Definition of a socket [duplicate]

I wanted to confirm whether the definition of a socket I've understood in a computer network context is true. A socket is file who is unique and named by local IP,Local port, Foreign IP and foreign ...
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What would happen if SYN and ACK are in the initial request?

I understand that a three-way handshake is used to form a TCP connection and that the basic outline of a handshake is: A sends a packet to B with a SYN bit B sends a packet to A with a SYN bit and an ...
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Congestion control behaviour of TCP Reno

Which behaviour of TCP Reno after 3 DUP ACK is correct: The one described in the Italian Wikipedia (https://it.wikipedia.org/wiki/Controllo_della_congestione_in_TCP#TCP_Reno). It says the new cwnd is:...
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Are NAT external:internal mapping types the same for UDP and TCP

Suppose I use a STUN server (UDP) to determine that a client's NAT randomly assigns external port values. Does this imply that the client's NAT will also assign random external port values when using ...
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Is it possible to move a persistent TCP connection?

Context: Say I have a global cloud service. In each datacenter, I have numerous persistent TCP connections to various client devices. The TCP connections are distributed across various nodes in the ...
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Is the distinction between ports under and above port 1024 exists only in TCP and UDP protocols?

Is the distinction between ports under and above port 1024 exists only in TCP and UDP protocols? I want to know if in other protocols (i.e. not TCP and UDP) such a distinction between "root" ...
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Does UDP can be exposed to stateful analysis?

From protocol theory we know that TCP is stateful protocol. Different stateful packet filters do filtration based on connection state. I.e. it can distinguish responses and replies. It's obviously for ...
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What does it mean for a website to return syn:false ack:true to my connect attempt? [closed]

I'm using a userspace TCP stack and I send a syn:true, ack:false to a website: [2021-06-20T19:30:24Z DEBUG async_smoltcp::packet_log] PHY >>>> [2021-06-20T19:30:24Z DEBUG async_smoltcp::...
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How to create a mapping between TCP segments or IP packets or fragments and TCP Windows? [closed]

I am searching for a method how I practically can determine the segments within a TCP window both when sending and receiving them? I want to modify IP packets per TCP window. I already looked into the ...
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Why large queueing delays are experienced as a packet arrival rate nears the link's capacity? [duplicate]

From the book "Computer Networks A top Down Approach": It says if hosts A and B both are sending at rate R/2 and router's outgoing link has a capacity of R. There will be delays experienced ...
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