Common sense of cloud server security settings

1、 Server external firewall

Server security group , Some are called security groups ; Some are called firewalls

2、 External firewall and internal firewall

External firewall ( Security group / A firewall )

Built in firewall (iptables/firewalld)

3、 Firewall function ：

A firewall is like a door , Imagine hiding your money in your room , At this time, a thief wants to steal your money , Thieves need to sneak into your front door first 【 External firewall ( Security group / A firewall )】,

And then sneak into your room 【 Built in firewall (iptables/firewalld)】

Although the built-in firewall and the external firewall are more secure when used together , But it affects the efficiency of data access , For speed , Sometimes just make sure it's safe , No need to be safer .

4、 Buy a good server , First, set up the external firewall

(1) Aliyun server ： Configuration release 80、443、ssh port (ssh The port is recommended to be modified , Do not use default 22)

(2) Tencent cloud server ： Configuration release 80、443、ping port 、ssh port (ssh The port is recommended to be modified , Do not use default 22)

Those who have purchased Tencent cloud services should pay attention to ：

Create security groups , When configuring rules , Do not choose to release all ports , To select custom , Then release 80、443、ping、ssh port

5、 modify ssh Port number

modify 22 Port idea ：

Let go at the external firewall first ssh Default port for 22, And then use xshell Connect with the remote connection tool ,

Then add... In the configuration file 22 port 、 new port , After the configuration is successful , After testing the new port, you can comment out the... In the configuration file 22 port , And the external firewall is prohibited 22 port

(1) Release the default port number at the external firewall 22

(2) edit /etc/ssh/sshd_config file , Add port number

vim /etc/ssh/sshd_config

• for example ： Add port 22、12345, Exit after saving

Add two ports to keep 22 The purpose of the port ： Prevent possible permissions and configuration issues , It can be closed after the test is successful 22 port

• The newly added port number range is recommended ： When you modify the port, you'd better choose 10000~65535 Port number between ,10000 The following are easily occupied by the system or some special software , Or when a new application is going to occupy the port in the future , But you took it first , Cause the software to fail to run .

(3) restart sshd

• CentOS 7.x The above systems , Carry out orders

systemctl restart sshd.service

• CentOS 6.x The following systems , Carry out orders

/etc/init.d/sshd restart

(4) Add firewall rules , Release the modified port

• if centos7 System ：

 Example opening 12345 port ：
*  Open port 12345: firewall-cmd --zone=public --add-port=12345/tcp --permanent
●  Close the port 12345: firewall-cmd --zone=public --remove-port=12345/tcp --permanent
*  Reload ： Make rules effective ： firewall-cmd --reload
*  see  zone=public Port information for ：firewall-cmd --list-ports --zone=public

• if centos6 System ：

# iptables Profile location /etc/sysconfig/iptables
#  add to 12345 Port rules 
iptables -A INPUT -m state --state NEW -m tcp -p tcp --dport 12345 -j ACCEPT
#  Preservation rules 
service iptables save
#  Restart the service 
service iptables restart

(5) The external firewall prohibits 22 port , Add the newly configured port

(6) modify xshell Port number in the attribute of , After the test connection is successful , take ssh Profile's 22 Port commented out

• modify xshell Port number in the attribute of , Test connection :

• After the test connection is successful , take ssh Profile's 22 Port commented out :

vim /etc/ssh/sshd_config

6、 The meaning of opening the firewall to release only the required ports

There is no need to expose ports casually , Otherwise there will be security risks , There are always a lot of machines scanning your ports , Try to access your service .

Especially like redis port , It may cause mining virus in you ; also ssh port 22, Every moment in the public network, someone tries to log in to your server by brutally cracking the password dictionary .

7、 Summarize the security common sense of using the server

* Minimize the number of exposed ports , And try to modify the default port number , Try to set complex passwords

* Do not use or install software from unknown sources

* Timely repair the vulnerabilities prompted by the system and known vulnerabilities of the software

* Check the log regularly

* Install anti-virus software ： Kaspersky Free Edition can resist blackmail virus ; install banip Software , error 5 Secondary cipher , Refuse 24 Hours , Prevent violent password cracking ;

Minimize the number of exposed ports

First expose the necessary ports http(80)、https(443)、ssh port ( Do not use default )、ping( Tencent server needs ); Other ports that need to be released , Consider using nginx Forwarding by proxy

Modify the default port ：

such as mysql The default port number is 3306, Need to use mysql If exposed , It is suggested to amend it to mysql The configuration file of is changed to another port number ;

Empathy ,redis If you want to use it on the public network , It is also suggested to modify redis The port number in the configuration file is another port number , No default 6379

Set complex password ：

You can set the password , And the password should not be set too simply .

such as mysql Set too weak password , Can also pass through myql Weave into the Trojan horse program ; And such as redis Release default port 6379, And then do not set redis password , It may be embedded in the mining program .

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