TCP Session: Syn Packet Acknowledgment
Written on 04:57 by Ahmet Emir
TCP Session: Syn Packet Acknowledgment
The abutting trace shows an acceptance to the syn packet:
TCP - Transport Control Protocol
Source Port: 80 World Wide Web HTTP
Destination Port: 1144
Sequence Number: 2873580788
Ack Number: 9356571
Offset: 6
Reserved: 0000
Code: %010010
Ack is valid
Synch Sequence
Window: 8576
Checksum: 0x5F85
Urgent Pointer: 0
TCP Options:
Option Type: 2 Maximum Segment Size
Length: 4
MSS: 1460
No More HTTP Data
Frame Check Sequence: 0x6E203132
Notice the Ack is valid, which agency that the antecedent anchorage was accustomed and the device
agreed to actualize a basic ambit with the basic host.
And actuality again, you can see that the acknowledgment from the server shows the antecedent is 80 and
the destination is the 1144 beatific from the basic host—all’s well.
Table 2.2 gives you a account of the archetypal applications acclimated in the TCP/IP suite, their wellknown
port numbers, and the Transport band protocols acclimated by anniversary appliance or process.
It’s important that you abstraction and acquire this table.
Notice that DNS uses both TCP and UDP. Whether it opts for one or the added depends on
what it’s aggravating to do. Even admitting it’s not the alone appliance that can use both protocols,
it’s absolutely one that you should bethink in your studies.
TCP/IP and the DoD Model 83
What makes TCP reliable is sequencing, acknowledgments, and breeze control
(windowing). UDP does not accept reliability.
Key Protocols That Use TCP and UDP
TCP UDP
Telnet 23 SNMP 161
SMTP 25 TFTP 69
HTTP 80 DNS 53
FTP 21
DNS 53
HTTPS 443
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