08-Lab-SSH-Hardening-and-sudo.md

Lab - SSH Hardening and sudo

• Take me to Lab

Solutions lab - SSH Hardening and sudo:

• All of These are the authentication methods used by SSH

• 22 is the default port used by SCP

• ssh -i is used to pass in the private key while connecting to a server via SSH?

• To create a user named jim on node01 host and configure password-less, Run

  
  $ ssh node01
  $ adduser jim
  set password you want
  Return back to controlplane host and copy ssh public key by running
  $ ssh-copy-id -i ~/.ssh/id_rsa.pub jim@node01
  test ssh access from controlpane host
  $ ssh jim@node01
  

• To change the password of user jim, Run

  
  $ ssh node01
  $ passwd jim
  switch to root user and run
  $ sudo su
  $ vi /etc/sudoers
  OR
  $ nano /etc/sudoers
  Add this line
  jim ALL=(ALL:ALL) ALL
  

• update user jim on node01 host so that jim can run sudo commands without entering the sudo password.

  ssh into node01 by running
  $ ssh node01
  $ vi /etc/sudoers
  change this line from
  jim ALL=(ALL:ALL) ALL
  To
  jim ALL=(ALL) NOPASSWD:ALL
  

• Add a new user rob on node01 host and set password to jid345kjf. Make user rob member of the admin

  
  SSH into node01 by running
  $ ssh node01
  Create user rob by running
  $ adduser rob
  Make it member of admin group by running
  $ usermod rob -G admin
  

• To investigate and fix this issue of sudo, Run

  
  $ ssh node01
  $ vi /etc/sudoers
  Edit this line to
  %admin ALL=(ALL) ALL
  

• To disable ssh root login and disable password authentication, Run

  
  $ ssh node01
  $ vi /etc/ssh/sshd_config
  Change: PermitRootLogin yes to no
  Change: #PasswordAuthentication yes to no
  Restart sshd service by running
  $ service sshd restart