Config ssh and ufw on Ubuntu

Change ssh config

First cd to the ssh local dict with cd /etc/ssh. Then edit the config file by

sudo cp sshd_config sshd_config.bak
sudo nano sshd_config

In the sshd_config:

1. If want to change the ssh port, e.g. add the port 43922 to the server, then add the line:

    Port 43922
   

   Then restart the sshd service by /etc/init.d/sshd restart or service sshd restart.

2. If want to login in the server only via rsa, then cancer the password-auth in sshd_config:

    PasswordAuthentication no     //yes改为no  
    ChallengeResponseAuthentication no  //yes改为no  
       
    RSAAuthentication yes   //去掉前面的注释  
    PubkeyAuthentication yes  //去掉前面的注释  
    AuthorizedKeysFile .ssh/authorized_keys  //去掉前面的注释  
   

   Then restart the sshd service.

Generate ssh rsa key

Cd to the ssh local dict, and then generate the ssh rsa files. After that, copy the id_rsa.pub to the server.

Attention: You may need to change the port number if the ssh port is not default as 22.

ssh-keygen -t rsa
ssh-copy-id user@192.168.xxx.xxx -p 22