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Questions tagged [packet]

A packet is one unit of binary data capable of being routed through a computer network.

This is a small amount of computer data sent over a network. Any time you receive data from the Internet, it comes to your computer in the form of many little packets.

Each packet contains:

  • A label which uniquely identifies it
  • The IP address of its origin and destination
  • A sequence number (for sorting)
  • A checksum (for error checking

The process of sending and receiving packets is known as "packet-switching." Packets from many different locations can be sent on the same lines and be sorted and directed to different routes by various computers along the way, the packets are then sorted by their sequence number once they reach their destination. It works a lot like the post office, except billions of packets are transferred each day, and most packets take less than a few seconds to reach their destination. Even FedEx same-day delivery can't compete with that.

Packet Definition. 2013. Packet Definition. [ONLINE] Available at: http://www.techterms.com/definition/packet. [Accessed 30 April 2013].

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Identifying last packet in a message sent by TCP

Say we have sender A sending a message to receiver B using TCP. Say the message to be sent from A to B is split into three packets of length 500 bytes, 500 bytes and 50 bytes, to be sent in that order. How does A indicate to B that the packet of…
Clive Long
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how to view ICMP request on public IP

I'm trying to check if a "ICMP" request on my public IP is being sent. I'm sending a request from "scapy" in python but i am spoofing the "src" address as my public IP. how do I check incoming "ICMP" requests on my public "IP" or are there any…
n00ta1dan
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Wireshark not capturing packets when applying "tcp and host 157.240.23.35" (157.240.23.35= ip address of facebook)

I am trying to Capture all TCP traffic to/from Facebook, during the time when i log in to my Facebook account using this "tcp and host 157.240.23.35" capture filter, but it is not capturing any packets. I found the ip address of Facebook on cmd…
vansika
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I want to know how to send packets from pcap file in Linux

In Windows OS, there is a program called "Packet Builder" by ColaSoft. This program has a function to retrieve and retransmit packets captured in Wireshark. I am trying to do the same in Kali Linux. How can I do this?
DownTop_oil
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What is the function of 802.11 (Retry Field)?

I have done some research but I'm still confuse with this field. I know its purpose is for retransmission if the bit is set to 1. However, is it correct for me to say that if the packet is sent but it does not receive acknowledgement back then it…
Skyb
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Why do we need port number in HOST header of HTTP when we have port number in TCP packet?

I'm aware of how HOST header can help us having multiple websites on a single IP address. In HOST header, we can optionally specify "port number". (80 by default for HTTP) In OSI model, layer-4 is responsible for dealing with "ports" and after…
S.B
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How to make use of full bandwidth?

Using WinPcap I crafted a series of custom UDP packets and injected them into the Ethernet layer. I sent 1000 packets, 1440 bytes each. It takes 2.1 sec for 100 Mbps bandwidth. How do I make use of full bandwidth?
krishnakumar
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IP Table rule to drop TCP packet and connection if PSH payload does not begin with specific bytes

We have an old multiplayer game (no source code) which crashes any time someone sends the server unexpected packets, and many of the players use telnet to do it with ease. I'm using iptables, and I want to filter out packets (and drop the…
user2616079
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How are Packet header fields ordered in binary stream?

I have just been refreshing my networking knowledge and came across a question regarding packet (segments, frames .. does not matter really). There are many diagrams of the packet or segment header on the internet and its quite understandable. How…
Jakub Sluka
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Wireshark does not show packets other than the packets related to my system

I use a Ubuntu Linux Machine and promiscuous mode is on in my WiFi NIC. These are the IP in my network 192.168.18.1 - My Router 192.168.18.2 - My Machine with Wireshark 192.168.18.3 - My Windows Machine (Victim) I want to capture the packets that…
Danwand N S
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how do I parse chunks in a byte array

So I have this big buffer in the shape of a byte array that I get from the client and I receive it on the server and it looks like this. [10, 0, 5, 11, 130, 0, 0, 0, 0, 0, 10, 0, 5, 11, 131, 0, 0, 0, 0, 0, 10, 0, 5, 11, 132, 0, 0, 0, 0, 0, 10, 0, 5,…
Riley Varga
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python network analysis: export DICOM object from pcap file

In Wireshark I can use the feature "export object => DICOM" to extract from network packets the DICOM file sent. I would like to do the same thing with Python or with Wireshark API, is it possible?
Furin
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What is jitter variance in networking?

Let's say I have a buffer. Packets arrive at the buffer and some of them are exiting the buffer (or all of them according to the parameters I'm giving into the system). I would like to ask the following question. When we want to calculate the jitter…
maritsamp2
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Unpack hex-encoded NSData

on peripheral:didReceiveWriteRequest a CBATTRequest returns hex-encoded NSData via request.value. This is what I have tried // Define struct typedef struct __attribute__((packed)) { UInt8 pktNo; UInt8 ctrlCmd; UInt8 txPowerRequest; …
AnonProgrammer
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Trying to Listen for GET on Port 80

I want to be able to read the URL GET requests coming to my server, ex: "www.JohnAlexINL.com/ping" or "http://johnalexinl.com/", et cetera. I've tried using TCPDump, but it gives me a bunch of garbled nonsense that I can't figure out how to…
JohnAlexINL
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