Basic configuration of newly installed ubuntu and basic configuration of ubuntu

Basic configuration of newly installed ubuntu and basic configuration of ubuntu

1. Enable the root account

1. Set a password for the root user.

Sudo passwd root

2. Switch to root Login

Su root

3. Enable login and edit Configuration

Sudo vi/usr/share/lightdm. conf. d/50-ubuntu.conf

# Automatically log on as root after startup

1 autologin-user=root2 greeter-session=unity-greeter3 user-session=ubuntu

# Manually enter the user name and password used to log on to the system

Greeter-show-manual-login = true

# Disabling a guest user

Allow-guest = false

4. Disable the root account again.

Sudo passwd-l root

Sudo passwd root is used to set the password of the root user to enable the root account. The account to be locked is sudo passwd-l, and the account to be opened is sudo passwd-u (it must be locked before, otherwise it is invalid ).

 

Ii. Enable the ssh service

Determine whether to install the ssh service

Ssh localhost

Ssh: connect to host localhost port 22: Connection refused as shown above, indicating that no installation has been performed.

1. First update the source

Sudo apt-get update

2. Install the ssh service

Sudo apt-get install openssh-server

3. Check whether startup is enabled

Ps-e | grep ssh

If ssh is displayed, it indicates that it has been started. If not, it will be manually started.

Sudo/etc/init. d/ssh start

4. Configure ssh-server. The configuration file is located in/etc/ssh/sshd_config. The default port is 22. For security purposes, it is generally customized as another port and then restarted.

Sudo/etc/init. d/ssh restart

Use putty or SSH Secure Shell to log on to windows.

 

3. Allow Remote root Login

Sudo vi/etc/ssh/sshd_config

Find PermitRootLogin without-password and change it to PermitRootLogin yes

Sudo/etc/init. d/ssh restart

Restart the ssh service

 

Appendix: SSH configuration file

By default, the configuration file of the sshd service is in/etc/ssh/sshd_config. Correct configuration items can further improve the security of sshd remote logon.

The configuration file content can be divided into the following three parts:

(1) Common SSH server listening options are as follows:

Port 22 // The listening Port is 22

Protocol 2 // use the SSH V2 Protocol

ListenAdderss 0.0.0.0 // The listening address is all addresses

UseDNS no // disable reverse DNS resolution

(2) Common User Logon control options are as follows:

PermitRootLogin no // disable root user logon

PermitEmptyPasswords no // disable empty password User Login

LoginGraceTime 2 m // login verification time is 2 minutes

MaxAuthTries 6 // The maximum number of retries is 6

AllowUsers user // only allow the user to log on, opposite to the DenyUsers Option

(3) Common Logon verification methods are as follows:

PasswordAuthentication yes // enable password verification

PubkeyAuthentication yes // enable key verification

AuthorsizedKeysFile. ssh/authorized_keys // specify the public key database file