Old boy Education Daily-May 2017 11-Basics point: What is the concept of listening ports in Linux systems?

1. Topics

Old boy Education Daily-May 2017 11-Basic points of knowledge:
What is the concept of listening ports in Linux systems?

2. Refer to the answer

The concept of listening port involves the concept of network concept and TCP state set conversion, which may be more complicated and inconvenient to understand, can be understood by simple?

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1. Metaphor of the entire server operating system as a villa

2. Each NIC on the server is likened to every room in the villa

3. IP address configured on the server NIC metaphor as a room for everyone

4. and the human ear in the room is like a listening port.

When the listener 0.0.0.0 address is used by default, everyone in the room is pricked up and waiting for the person outside the villa to call
When the user outside the Villa shout to the room 1 people, the room 1 inside the person will respond;
When the user outside the Villa shout to the Room 2 people, the room 2 inside the person will respond;
by analogy;
Such access means that the address of all the network cards of this server, and the corresponding ports are in the listening state, very insecure;
Hackers will enter the villa and attack as long as they connect with a person in the villa.
Therefore, it is necessary to specify the listening address information according to the different service of the system, designate the corresponding person to be able to respond, the other person will close the ear, do not respond
This is the simple understanding of the concept of monitoring, I do not know you understand, hope to give a supplement.

3. Statistical information

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Old boy Education daily-May 2017 11-Basics point: What is the concept of listening ports in Linux systems?