Linux Network Management

ISO: International Organization for Standardization

OSI: development system Interconnect model

Send the data, the upper layer to the lower layer, and then from the host a physical layer to the physical layer of Host B, the physical layer of Host B is transferred up

When data is accepted, the lower layer goes to the upper layer and is passed from the physical to the application layer

On the three floor to provide services to users, the next four layers of actual data delivery services

Four-tier model of TCP/IP protocol

network interface Layer :

The network access layer corresponds to the physical layer and Data link layer in the OSI Reference Model. Responsible for monitoring the exchange of data between the host and the network. In fact, TCP/IP does not itself define the protocol for that layer, and it uses its own physical layer and Data Link layer protocol by each network participating in the interconnection, and then connects to the TCP/IP network access layer.

　　Address Resolution Protocol (ARP) works in this layer, the data link layer of the OSI Reference Model. Translate IP addresses into physical addresses

　　

Internetwork Interconnect Layer :

The internetwork Interconnect layer corresponds to the network layer of the OSI Reference Model, which mainly solves the host-to-host communication problem. It contains protocols that design the logical transmission of packets over the entire network.

There are three main protocols in this layer: Internet Protocol (IP), network Group Management Protocol (IGMP), Internet Control Message Protocol (ICMP)

Transport Layer:

The transport layer corresponds to the transport layer of the OSI Reference Model, providing an end-to-end communication function for the application layer entities, guaranteeing the sequential transmission of the packets and the integrity of the data.

This layer has two main protocols: Transmission Control Protocol (TCP), User Packet Protocol (UDP)

　　

Application layer:

　　The application layer corresponds to the upper three layers of the OSI reference Model, providing a variety of services to the user. For example: FTP, Telnet, DNS, SMTP, etc.

　　

Comparison of TCP/IP with OSI model

Same point:

1. The concept of hierarchy is adopted

2. Capable of providing connection-oriented and non-connected two communication service mechanisms

Different points:

1. The former four-layer model, the latter seven-storey

2. Different requirements for the reliability spectrum

3. The OSI model was designed prior to protocol development and was universal. TCP/IP is a protocol set and then a model that does not apply to non-TCP/IP networks

IP Address

　　

The number of bytes in the IP header is not necessarily 20 bytes, it is not fixed, which is why the IP4 protocol transmission is not IP6 transmission fast reason, IP6 Baotou is fixed, each transmission does not need to judge the length of the Baotou

Port

To view native enabled ports: Netstat-an

-A: View all connections and listening ports

-N: Displays the IP address and port number without displaying the domain name and service name

DNS role (abbreviation for domain Name System, also known as Ming Chen Parsing)

In the Internet, communication via IP address

The IP address is indicated by the numeral, the memory difficulty, changes the domain name convenience memory. Example: 116.213.123.342 ==> www.baidu.com

Linux Network Management