LAN / WAN

IPP - Print via HTTP or HTTPS

The Internet Printing Protocol (IPP) is a standard network protocol for remote printing as well as managing print jobs, media size, resolution, and so forth in distributed environments.

The idea behind the IPP is to define a protocol for end users to print over the Internet, provide users with the same printing controls and concepts that they use to print locally or to LAN-attached printers. There are two main components to IPP:

ICMP report network error

ICMP or Internet Control Message Protocol is one of the most important network protocols in TCP/IP protocol suite. The Internet Protocol is not designed to be absolutely reliable. As such, ICMP is designed to be used by networked computers' operating systems to send error messages to show that a requested service is not available or that a PC or router could not be reached.

What is computer network?

A computer network is a group of two or more computer systems linked together. The purpose of having computer network is to allow computers to communicate with each other and share resources and information.

The type of communication in computer network might be a download of video from Youtube, using your web browser like Firefox, Internet explorer to read CNN news; talking to your friends using Instant Messenger like MSN, Google Talk and so on.

Network Protocol - the Rule of Computer Communication

In computing, a protocol is a convention or standard that controls or enables the connection, communication, and data transfer between computing devices.

Modern network systems are made up of a variety of different systems running on many different platforms. In order for computers on these platforms to exchange information, there must be a preexisting agreement as to how the information will be structured and how each side will send and receive it.

Domain Name System (DNS) - the basic TCP/IP system

Domain Name System (DNS) is one of the base system service in TCP/IP. It allows hosts (PC, servers) on TCP/IP networks to be addressed by names. Though IP addresses allow computers and routers to identify each other efficiently, humans prefer to work with names rather than numbers.

DNS is used by email system, windows active directory, any web access and so on. Without DNS, a user will need to know the IP addresses of all the services s/he required.

OSI Seven Layer Network Reference Model - Addressing and Example

The OSI (Open Systems Interconnection) Seven Layer Network Reference Model is used for learning of network infrastructure. It is an abstract description of computer network protocol design.

The original Internet TCP/IP protocol specifications defined a four layer model (application, transport, network and physical). However, in OSI 7 Layer Network Reference Model, there are 7 layer introduced. From top to bottom, the name of the layers are Application, Presentation, Session, Transport, Network, Data-Link, and Physical Layers.

HTTPS to secure web transaction

A tremendous amount of information was passed back and forth to the Internet everyday. Most of the time, the protocol used in this communication is HTTP or HyperText Transfer Protocol.

In HTTP, all data is transferred in clear text - data such as User Identification (userid) and password will be transmitted as clear text as well. This is a security issue as anyone can sniff these userid/password and gain access to private information.

Established in Access List configuration

After the TCP three-way handshake, all subsequent TCP segments that use the session will have at least the ACK bit set. The "established" keyword on an ACL prevents pre-existing TCP sessions that are built across the router to be torn down when the ACL is applied to an interface.

For example,

access-list 101 permit tcp any 202.224.119.0 0.0.0.255 established

SOAP Basic

SOAP is acronym for Simple Object Access Protocol.

A SOAP method is an HTTP request/response that complies with the SOAP encoding rules.

Basically, SOAP = HTTP + XML

A SOAP request could be an HTTP POST or an HTTP GET request.

The HTTP POST request specifies at least two HTTP headers: Content-Type and Content-Length.

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