Packet 7 is again from the server with seq 1453 (1452+1), length 1452, acks 710 (the client hasn’t sent anything new) Packet 6 is again from the server with seq 1 (since the previous packet had length 0), ack 710, length 1452 Because the server didn’t manage to send any data yet, it sends an empty ack, otherwise the ack would be piggybacked in the data. Indeed packet 5 from the server is a packet with seq 1 and ack 710 length 0. So the next sequence number should be 710 and the ack from the server should be 710. This packet has an initial sequence number of 1 and 709 bytes segment length.
The client sends an http request, packet 4, requesting a GET / http/1.1 (this is the root document). You can see also that although the tcp length is 0, the client and the server increase the sequence number by 1. The server responds with a SYN-ACK with window size 29200 (hex 7210), scaling factor 8 (hex 08, multiply by 2^8=256) Len=0, MSS=1452 and SACK permitted. It supports an MSS of 1460, a window size of 8192 (hex 2000) with a scaling factor of 2 (hex 02) (multiply by 2^2=4) and selective acks.
The important this to note is the options section. In the beginning the client sends a SYN request. If we captured somewhere in between, the RTT would be (ACK - SYN) / 2 SYN, SYN-ACK, ACK Othwerwise I would look at the time between SYN-ACK and ACK. In order to see the time or delta between displayed packets you have to go to View, Time Display Format, Seconds since previous displayed packetīecause we are capturing at the source the RTT is the time between SYN and SYN-ACK which is 0.214. So the capture is obviously at the source. This is very obvious because I have as source an internal IP address, but I could have figured it out from the time interval between SYN, SYN-ACK and ACK.
USE WIRESHARK HTTP DOWNLOAD
If you want to download the pcap file click here
USE WIRESHARK HTTP FULL SIZE
you can do right click, open in a new tab, to see full size image. In this post we will use wireshark to analyze an http connection, where a client requests a single webpage from a server.
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