Line Printer Daemon (LPD)

Line Printer Daemon (LPD)

Another TCP/IP upper-layer service that is in widespread use is the Line Printer Daemon (LPD). It resides on a network printer or print server and responds to TCP/IP printing requests from the printing clients (known as LPR clients). It was developed as the printing services for UNIX. But, because of the tight marriage between UNIX and TCP/IP, the LPD service became the default
print service used with TCP/IP.

Note:

A daemon is a program that acts like a terminate and stay resident (TSR) application
by loading into memory and lurking there for any trigger that calls upon its services.

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Internet Message Access Protocol, Version 4 (IMAP4)

Internet Message Access Protocol, Version 4 (IMAP4)

Internet Message Access Protocol (IMAP) allows users to download mail selectively, look at the message header, download just a part of a message, store messages on the e-mail server in a hierarchical structure, and link to documents and Usenet newsgroups. Search commands are also available so that users can locate messages based on their subject, header or content. IMAP has strong authentication features and supports the Kerberos authentication scheme originally developed at MIT. The current version of IMAP is version 4.

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Lightweight Directory Access Protocol (LDAP)

Lightweight Directory Access Protocol (LDAP)

In large networks, most administrators have set up some kind of directory that keeps track of users and resources (e.g., NDS, Active Directory). In order to have a standard method of accessing
directories, the Lightweight Directory Access Protocol (LDAP) was developed. It allows clients to perform object lookups with a directory using a standard method. LDAP was originally
specified as RFCs 1487 (version 1) and 1777 (version 2), with RFC 3377 proposing the more commonly used third version, which fixes a number of shortcomings in the protocol.

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Post Office Protocol (POP)

Post Office Protocol (POP)

Post Office Protocol (POP) provides a storage mechanism for incoming mail; the latest version of the standard is known as POP3. When a client connects to a POP3 server, all the messages
addressed to that client are downloaded; there is no way to download messages selectively. Once the messages are downloaded, the user can delete or modify messages without further interaction with the server. In some locations, POP3 is being replaced by another standard, IMAP.

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Secure Copy Protocol (SCP)

Secure Copy Protocol (SCP)

While FTP is easy to use to transfer files, it has a major security problem in that the username and password are sent along with the file request in clear text (i.e., not encrypted). It would be a relatively simple matter for someone to intercept that information and use it for other purposes. 
      Secure Copy Protocol (SCP) was designed to overcome this limitation. It uses SSH to establish and maintain an encrypted connection between hosts. The file transfer can then take place
without fear of password or data interception.

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Simple Mail Transfer Protocol (SMTP)

Simple Mail Transfer Protocol (SMTP)

Simple Mail Transfer Protocol (SMTP) allows for a simple e-mail service and is responsible for moving messages from one e-mail server to another. The e-mail servers run either Post Office
Protocol (POP) or Internet Mail Access Protocol (IMAP) to distribute e-mail messages to users.

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Network News Transfer Protocol (NNTP)

Network News Transfer Protocol (NNTP)

The Network News Transfer Protocol (NNTP) is the TCP/IP protocol used to access Usenet news servers. Usenet news servers contain thousands of individual message boards known as
newsgroups. Each newsgroup is about a particular subject (cars, dating, computers, etc.). Chances are, if you have an interest, there is a newsgroup about it. The details of the NNTP protocol
are specified in RFC 977.

Note:

Because of the relative complexity involved in configuring a news reader program,
there are many websites (including google.com) that have made newsgroup
access available through the Web.

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Secure File Transfer Protocol (SFTP)

Secure File Transfer Protocol (SFTP)

Secure File Transfer Protocol (SFTP) is used when you need to transfer files over an encrypted connection. It uses an SSH session (more on this later) which encrypts the connection. The SFTP
protocol then is used to transfer files over this encrypted connection. Apart from that, it functions exactly as the FTP protocol does: It is used to transfer files between computers.

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Trivial File Transfer Protocol (TFTP)

Trivial File Transfer Protocol (TFTP)

Trivial File Transfer Protocol (TFTP) is a “stripped down” version of FTP, primarily used to boot diskless workstations and to transfer boot images to and from routers. It uses a reduced feature set (fewer commands and a smaller overall program size). In addition to its reduced size, it also uses UDP instead of TCP, which makes for faster transfers but with no reliability.

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File Transfer Protocol (FTP)

File Transfer Protocol (FTP)

File Transfer Protocol (FTP) provides a mechanism for single or multiple file transfers between computer systems; when written in lowercase as “ftp,” it is also the name of the client software used to access the FTP server running on the remote host. The FTP package provides all the tools needed to look at files and directories, change to other directories, and transfer text and binary files from one system to another. FTP uses TCP to actually move the files.

Note:

We’ll look at how to transfer files using FTP in detail in the next chapter.

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Simple Network Management Protocol (SNMP)

Simple Network Management Protocol (SNMP)

Simple Network Management Protocol (SNMP) allows network administrators to collect information about the network. It is a communications protocol for collecting information about
devices on the network, including hubs, routers, and bridges. Each piece of information to be collected about a device is defined in a Management Information Base (MIB). SNMP uses UDP
to send and receive messages on the network.

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The Application Protocols

The Application Protocols
Application layer protocols are built on top of and into the TCP/IP protocol suite and are available on most implementations. The following list includes such protocols:

 SNMP              FTP

TFTP                SFTP

SMTP               POP3

IMAP               LPD

NFS                  Telnet

SSH                  HTTP

HTTPS              NTP

NNTP              SCP

LDAP               IGMP

LPR                         

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