How to understand ip port protocol

How to understand the ip port protocol? in view of this problem, this article introduces the corresponding analysis and answer in detail, hoping to help more partners who want to solve this problem to find a more simple and feasible way.

Every computer on the Internet has a unique 32-bit address, the ip address.

When we access the server, we must use this ip address

The local area network also has a reserved ip address at the beginning of 192 UniUniverse 172. The ip address of the LAN is also unique.

NAT mode, the host computer ip is unique in the LAN, the choice of NAT mode to create a virtual machine, the virtual machine is a new local area network (private network).

The teacher's machine ip is 192.168.33.128

Simple concept of Port

192.168.33.128 represents a host, but there may be many services on the host

The different service functions on a host are distinguished by ports and then accessed by outsiders.

SSH remote connection Service 22

The simple concept of protocol

Chinese, English, French, different services provide different ports, corresponding to different functions, the mode of communication may also be different, this way of communication can be understood as a protocol.

Different service functions on a host are distinguished by ports. Different services and communication between clients and servers may use different protocols.

Ip,port,protocol (protocol)

Remote connection service.

Troubleshooting:

1. Whether the two machines are smooth depends on the physical network (wireless network card, whether the ip is correct)

Ping ip-t to check whether the physical network is unobstructed

Impassable:

a. There is a problem with the physical link from the client to the server.

Network card, IP, network cable, firewall

2. Whether the service is good

Whether the ssh service is good

Detection method: operate on which machine from which machine is connected

Telnet 192.168.33.128 22 (ip and port of the server)

Telnet can also be connected remotely, but it is rarely used because it is not encrypted.

The possible reasons for the failure are:

a. Server port firewall blocking

[root@oldboy ~] # / etc/init.d/iptables stopiptables: Setting chains to policy ACCEPT: filter [OK] iptables: Flushing firewall rules: [OK] iptables: Unloading modules: [OK]

b. The port is not open, and the server does not listen on the port to which you are connected.

[root@oldboy ~] # netstat-tunlp | grep 22 (take port 22 of ssh service as an example) tcp 00 0.0.0.0 tunlp 22 0.0.0.0 ssh 00: 22:: * LISTEN 1559/sshd/etc/init.d/sshd restart (restart ssh service)

Client tool: SecureCRT,Xshell,putty

Server ssh service, process name sshd,openssh (for connection), openssl (for encryption)

The answer to the question on how to understand the ip port protocol is shared here. I hope the above content can be of some help to you. If you still have a lot of doubts to be solved, you can follow the industry information channel for more related knowledge.