AWS: Linux EC2 SSH new user password setup

DevOps Jul 13, 2023

The default user for AWS EC2 Ubuntu server is ubuntu

Initial login with .pem file

$ ssh -i filename.pem ubuntu@ec2...-117-96.com

the filename.pem can be path to that file e.g. ~/.ssh/filename.pem

Remarks:

The server location is follow @ sign. If you don’t know this click “Actions” in the AWS EC2 dashboard and then “Connect” this will show up.
If you lose .pem file, you have no choice but delete and create new EC2.

Note: ubuntu user

The default user ubuntu is special since:

This is not root user
This user has admin privilege
This user has no password i.e. sudo without password

Step 2: Create new user

Create new user for SSH login

In this example, user001

$ sudo adduser user001
$ sudo cat /etc/passwd
// should found user001 here

Adding sudo special power

$ sudo visudo
// seeing who can sudo found group admin can do sudo// found
// %admin ALL=(ALL) ALL
$ usermod -aG admin user001
// add user001 to group admin

Bonus, checking this user is working

$ su user001
// type password
// check correct password is set$ groups
// check groups$ sudo cat /etc/passwd
// check this user can sudo

Step 4: Change ssh server config

Enable user/pass login from outside

// file: /etc/ssh/sshd_config
...PasswordAuthentication yes

Step 5: Restart ssh server to make change effect

restart the server to make it load the new config i.e. sshd_config

$ systemctl
// finding something related to ssh found ‘ssh.service’$ systemctl restart ssh
// at this steps use user chakrit
// ubuntu haven’t have a password

Now we’re done with creating user/pass login

Cheers