Zero-Trust VPS Hardening: The 10 Essential Rules for Production Linux Nodes
From ed25519-sk hardware security keys and non-standard SSH ports to kernel sysctl hardening and auditd logging, here is our security checklist.
1. Disable Password Authentication and Root Login
The vast majority of automated internet scans target root SSH passwords with dictionary attacks. Disabling root SSH password logins immediately eliminates 99.4% of automated brute force noise:
bash
In /etc/ssh/sshd_config.d/99-hardened.conf:
PermitRootLogin prohibit-password
PasswordAuthentication no
ChallengeResponseAuthentication no
KbdInteractiveAuthentication no
UsePAM yes
2. Enforce Ed25519 or FIDO2 Hardware Keys
Standard RSA 2048 keys are deprecated in modern cryptography standards. Adopt modern Edwards-curve cryptography (Ed25519) or hardware FIDO2 tokens (Yubikey):
bash
ssh-keygen -t ed25519-sk -O resident -C "production-admin@nodexvps"
3. Kernel Sysctl Network Parameter Hardening
Prevent IP spoofing, drop invalid SYN packets, and ignore ICMP broadcast requests by tuning /etc/sysctl.d/99-security.conf:
bash
net.ipv4.conf.all.rp_filter = 1
net.ipv4.conf.default.rp_filter = 1
net.ipv4.tcp_syncookies = 1
net.ipv4.conf.all.accept_source_route = 0
net.ipv6.conf.all.accept_source_route = 0
net.ipv4.conf.all.accept_redirects = 0
net.ipv6.conf.all.accept_redirects = 0
Apply updates instantly with sudo sysctl --system.
4. Enable NodexVPS Cloud Firewall
Combine host-level UFW/nftables with NodexVPS out-of-band edge firewall rules to drop malicious traffic before it ever consumes a CPU cycle on your virtual network interface.