Port Number; Browser - Furuno Felcom 250 Service Manual

SYN (Synchronize Flag)
When the bit is set to 1, a request will be made to establish the connection. The
segment which has this bit set to 1 is sometimes referred to as SYN segment. SYN
segments would have the default value for the sequence number contained in the
sequence number field.
FIN (Synchronize Flag)
When this bit is set to 1, a request will be made to disconnect the connection. When
you wish to disconnect the connection, both parties are to send/receive a segment
where this bit is set to 1. This segment is sometimes referred to as the FIN segment.
Window
16 bit; it is used for the recipient to notify the currently receivable data size to the sender. The
sender will not send a data larger than this volume. When the sender obtains the latest
window size, it will send a segment where this field is set to 0.
Checksum
16 bit; TCP calculates the data sum in order to guarantee the data reliability.
Urgent Pointer
16 bit; it is valid when the URG bit for the code bit field is set to 1. The pointer which shows
the location of the data requiring urgent processing is stored.
Options
Consisted of the option field + padding field = 32 bit. The padding field is adjusted by being
filled with 0.

Port Number

Port No. is the number for identifying services upon TCP or UDP, and is described in
the TCP or UDP header. As for the details, please refer to page AP4-17.
For example, when the port number is 25, it represents SMTP, and when the port
number is 69, it represents TFTP. The port number frame is 0-65535, and there are 3
types of port numbers as described below;
Well Known Port Number: 0 - 1023
Highly public and useful ports, and the port numbers are officially registered
port numbers. They are mainly used by the server side which provides the
services.
Registered Port Number: 1024 - 49151
The ports used by the software created by the users, and the port numbers are
officially registered port numbers. They are mainly used by the server side
which provides the services.
Dynamic Port Number: 49152 - 65535
These port numbers are not officially registered. They are used mainly by the clients for
dynamic applications.

Browser

A software used for viewing the data or information in a collective manner. When the
term browser is simply referred to, it would often refer to the Web browser which is
used for viewing the information within the WWW.
AP4-11
Appendix 4. Abbreviations