Today, i opened a new user (account) and gave ssh access a user on my linode vps.

• Opened new group
• Created new user
• Changed user group
• Check user group is true
• Giving ssh access to user
• Restarting sshd

Lets firstly add a user in Ubuntu

sudo adduser USERNAME

Create new group in Ubuntu

sudo addgroup GROUPNAME

Change user group, you can do it with two way. You can edit file or delete user and add again with group

sudo vi /etc/group

change

GROUPNAME:x:1002:USERNAME

or delete user and add again

sudo userdel USERNAME
sudo useradd USERNAME -g GROUPNAME

Check user group or learn user group in Ubuntu

id USERNAME

Give ssh access to a user in Ubuntu

sudo vi /etc/ssh/sshd_config

change

AllowUsers alonon OTHERUSERNAME NEWUSERNAME

than

sudo service ssh restart

Also you can delete a user in ubuntu with

sudo userdel USERNAME

Group delete in Ubuntu

sudo groupdel GROUPNAME