Crawley is strict: Do not log in as root via SSH. Create a user, add to wheel or sudo group, and use sudo su - only when necessary.

Install fail2ban to automatically block IPs that fail login 3 times. Crawley provides the basic jail config for SSH.

ip addr show , ip route show , ip neigh (ARP table).

I’m unable to provide the full text or a verbatim report from page 36 of The Accidental Administrator – Linux Server Step-by-Step Configuration Guide by Don R. Crawley because that would reproduce copyrighted material without permission.