CentOS 8 SSH Server Hardening & Create Users

First of all i have to say i am studies Linux for 2 days and this is first topic i learned , I might have something wrong about this , and purpose of this content is reminder about something i learned.

Topics

• Create new users for ssh
• Test new users for ssh
• Hardening

After installed CentOS 8 and got root password then login and add new users for SSH (In this case is ssh-t3st ) by this command.

useradd ssh-t3st

Then settings password for ssh-t3st by this command and input password do you want to set.

passwd ssh-t3st

create user & set password for user

Then test login by user we create through SSH

Test login ssh by new user

Now you can remote to server by used ssh , lets hardening ssh by block root login through ssh and change ssh service port for decrease chance to got attack by Bot or Attacker

We will hardening by modify ssh configuration file (/etc/ssh/sshd.config) * you can use :set number for view line number

vim + :set number

Then edit line 17 by type i for insert text delete # for and change #port 22 to port 2222 in this case i use port 2222 for new ssh service port

Change port number ssh service

Then edit line 46 PermitRootLogin yes to PermitRootLogin no for not permit use root user to login

Change PermitRootLogin

Then save change of this file by :wq ( :wq is mean write and quit ) , then restart sshd service systemctl restart sshd

can’t restart service sshd

In this case we have problem to restart sshd service , if you have SE-Linux on server like this (I create cloud server service for test) you have to add permission in SE-Linux for this by use this command

semanage port -a -t ssh_port_t -p tcp 2222

it mean [SE-Linux( semanage ) manageport ( port) add( -a) service type ( -t) ssh_port_t (name of service) protocol ( -p) tcp 2222(port number)

Now you can restart sshd service

after add semanage allow tcp 222 , now can restart service

SSH Service port change from port 22 to 2222

Now lets test it should can’t login by root user and have to use port 2222 to login only

can’t use root user to login & only use port 2222 to login

Done !

Hope you guys got something from this content and sorry if i mistaking something feel free to advise me

Thanks you.