Other Upper-Layer Protocols
Various other upper-layer protocols play an important role in the success of the TCP/IP protocol suite as a flexible, well-rounded, self-contained group of protocols:
UDP
SMB
AFP
IC...
Saturday, November 30, 2013
Line Printer Remote (LPR)
Line Printer Remote (LPR)
When using pure TCP/IP printing (as with UNIX workstations or when used for cross-platform printing), the LPD/LPR pairing is used most often. The Line Printer Daemon (LPD) is installed
on the print device and manages the printer as well as the print jobs. The Line Printer Remote (LPR) software is the printing client...
Internet Group Management Protocol (IGMP)
Internet Group Management Protocol (IGMP)
The Internet Group Management Protocol (IGMP) is a TCP/IP protocol that is used to manage IP multicast sessions. It uses special IGMP messages to learn the layout of the multicast groups
and which hosts belong to which groups. Additionally, the individual hosts in an IP network use IGMP messages...
Friday, November 29, 2013
Network Time Protocol (NTP)
Network Time Protocol (NTP)
Network Time Protocol (NTP), originally developed by Professor David Mills at the University of Delaware, is used to synchronize (or set) computer clocks to some standard time source, which is
usually a nuclear clock. This protocol (along with synchronization utilities) keeps all computers on a network set to...
Hypertext Transfer Protocol Secure (HTTPS)
Hypertext Transfer Protocol Secure (HTTPS)
Hypertext Transfer Protocol Secure (HTTPS), also referred to as Secure Hypertext Transfer Protocol (which you will see abbreviated as SHTTP or S-HTTP), is a secure version of HTTP that provides a variety of security mechanisms to the transactions between a web browser and the server. HTTPS...
Hypertext Transfer Protocol (HTTP)
Hypertext Transfer Protocol (HTTP)
Hypertext Transfer Protocol (HTTP) is the command and control protocol used to manage communications between a web browser and a web server. When you access a web page on the
Internet or on a corporate intranet, you see a mixture of text, graphics, and links to other documents or other Internet resources....
Secure Shell (SSH)
Secure Shell (SSH)
The Secure Shell (SSH) protocol is used to establish a secure Telnet session over a standard TCP/IP connection. It is used to run programs on remote systems, log in to other systems, and move
files from one system to another, all while maintaining a strong, encrypted connection. It replaces such utilities as rsh and rlogin...
Telnet
Telnet
Telnet is a terminal emulation protocol that provides a remote logon to another host over the network. It allows a user to connect to a remote host over a TCP/IP connection as if they were sitting
right at that host. Keystrokes typed into a Telnet program will be transmitted over a TCP/IP network to the host. The visual responses...
Network File System (NFS)
Network File System (NFS)
UNIX systems are unique in the way they access files and are actually fairly elegant. The Network File System (NFS) Application layer protocol was originally designed to allow shared file
systems on UNIX servers to appear as local file systems on UNIX clien...
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...
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...
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...
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,...
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.
...
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 use...
Thursday, November 28, 2013
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,...
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...
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...
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...
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...
Wednesday, November 27, 2013
Tuesday, November 26, 2013
Routers and Routing
Routers and Routing
As you already know, routing is the process of getting your data from point A to point B. Routing datagrams is similar to driving a car. Before you drive off to your destination, you determine
which roads you will take to get there. And sometimes along the way, you may change your mind and alter your route.
...
Address Resolution Protocol (ARP) and Reverse ARP (RARP)
Address Resolution Protocol (ARP)
The Network layer protocol, ARP, associates the physical hardware address of a network node to its already known IP address. Using ARP, an IP process constructs a table (known as the ARP cache) that maps logical addresses to the hardware addresses of nodes on the local network. When a node needs...
Internet Control Message Protocol (ICMP)
Internet Control Message Protocol (ICMP)
ICMP works at the Network layer and provides the functions used for Network layer management and control. Routers send ICMP messages to respond to undeliverable datagrams by placing
an ICMP message in an IP datagram and then sending the datagram back to the original source. The ping command—used in...
The Internet Layer Protocols
The Internet Layer Protocols
The Internet layer of the DoD model is made up of various protocols, with the three main protocols being the Internet Protocol (IP), the Internet Control Message Protocol (ICMP), and the
Address Resolution Protocol (ARP). The following sections...
Monday, November 25, 2013
The Transmission Control Protocol
The Transmission Control Protocol
TCP is the Transport layer of the protocol and serves to ensure a reliable, verifiable data exchange between hosts on a network. TCP breaks data into pieces, wraps the pieces with the information needed to identify it as a piece of...
TCP/IP and the OSI Model
TCP/IP and the OSI Model
As you learned in Chapter 2, “The OSI Model,” the OSI model divides computer-to-computer communications into seven connected layers; TCP/IP uses the Department of Defense (DoD)
model, which describes communications in only four layers, as Figure...
TCP/IP Design Goals
TCP/IP Design Goals
When the U.S. Department of Defense began to define the TCP/IP network protocols, their design goals included the following:
TCP/IP had to be independent of all hardware and software manufacturers. Even today, this is fundamentally why TCP/IP makes such good sense in the corporate world: It is...
A Brief History of TCP/IP
A Brief History of TCP/IP
The first Request for Comments (RFC) was published in April 1969, laying the groundwork for today’s Internet, the protocols of which are specified in the numerous RFCs monitored,
ratified, and archived by the Internet Engineering Task Force (IETF). TCP/IP was first proposed in 1973 and was split into separate protocols,...
Introducing TCP/IP
Introducing TCP/IP
Because TCP/IP is so central to working with the Internet and with intranets, you should understand it in detail. We’ll start with some background on TCP/IP and how it came about and then move on
to the descriptions of the technical goals defined by the original designers. Then you’ll get a look at how TCP/IP compares...
