SSH brute force attacks
On the desktop, download ncrack
Install libssl-dev package, then compile and install
ncrack by following the instructions on the source web site.
Install crunch package on the desktop, which is needed
for generating a password dictionary.
Deploy a new VM, testub, by cloning kvm1.
Deploy a new VM, testcent, by cloning CentOS7.
Make the both host names resolvable by creating their entries in /etc/hosts file on the desktop.
On the both VMs, create user account jerry. Assign password
jerry1 to user jerry. If the password PAM module doesn't allow you setting a such simple password, use command mkpasswd and enter the hash manually into /etc/shadow. Check if user jerry can login to the VM.
On the desktop, generate a password table, passwords.txt, by running crunch:
Run SSH bruteforce attacks onto account jerry on the both VMs:
crunch 5 6 jerry123 -o passwords.txt
Within a few minutes, ncrack should be able to identify the correct
password for user jerry from passwords.txt list.
ncrack -vv --user jerry -P passwords.txt testub:22
ncrack -vv --user jerry -P passwords.txt testcent:22