Fail2ban — ban status
fail2ban-client status # list active jails fail2ban-client status sshd # detail for one jail fail2ban-client set sshd unbanip X.X.X.X # unban an IP
Firewall
ufw status verbose # show all rules ufw allow 8080/tcp # open a port ufw delete allow 8080 # close it again
Client isolation summary
SFTP : chroot to /var/www/clients/<client> — cannot escape PHP : FPM pool per client, open_basedir enforced MySQL : dedicated user, single database — no cross-client access Shell : login shell is /usr/sbin/nologin — no interactive access
SSH hardening (applied)
PasswordAuthentication yes (for ubuntu admin) PermitRootLogin prohibit-password ClientAliveInterval 30 (keepalives for poor connections) SFTP clients ForceCommand internal-sftp, no TCP forwarding
Check for listening services
ss -tulpn
View auth failures
journalctl -u sshd -n 50 --no-pager journalctl -u postfix -n 50 --no-pager