Firewall; Ftp (File Transfer Protocol); Ipsec (Security Architecture For Internet Protocol); Icmp (Internet Control Message Protocol) - Furuno Felcom 250 Service Manual

Firewall

A system which is located in between 2 networks – for example, LAN and the Internet –
to prevent from having unauthorized invasion made by external parties and to allow
authorized data only to go through it. The simple ones would have the IP addresses and
communication protocol port numbers for those allowed set in the router where those
not matching the contained list would not be able to have their packets go through this
part.

FTP (File Transfer Protocol)

FTP is a communication protocol used for forwarding files upon the network.
Files can be forwarded between optional hosts as long as it is upon the same protocol.
This is usually used for forwarding files between the client and the server (FTP server.)
Its purpose is to;
Upload various data files for Web pages from client PCs to the Web server
Download files from PC software distribution sites or FTP file servers where data
is stored to client PCs

IPSec (Security Architecture for Internet Protocol)

A protocol which provides functions for preventing from having data tampered by the IP
packets or for ensuring confidentiality by using the encryption technology.
Since the IP packets will be sent / received by being encrypted, the application software
which use the upper protocols such as TCP or UDP will not need to be conscious that
IPsec is being used.

ICMP (Internet Control Message Protocol)

A protocol for forwarding IP error messages or control messages.
It is used for confirming the statuses of each other between the computers or network
equipments connected by TCP/IP.
IDENT (Identification Protocol)
The server used for returning additional information regarding the users of the
connected server.
IDENT protocol identifies the owner of the connections between the client and the
server. It is used most commonly for sending E-mails; when E-mails are sent, the client
connects to the server first, and then the server re-connects to the client using IDENT to
identify who the client is.
AP4-13
Appendix 4. Abbreviations