Kernel hardening with sysctl on Slackware

1. When to use it

Useful when you want to raise the baseline defense level without moving into invasive customization.

2. Base setup

cat > /etc/sysctl.d/99-hardening.conf <<'EOF'
kernel.randomize_va_space = 2
net.ipv4.conf.all.rp_filter = 1
net.ipv4.icmp_echo_ignore_broadcasts = 1
fs.protected_hardlinks = 1
EOF
sysctl --system

Adjust host names, IPs, interfaces, paths, and versions to the real system before making the change persistent.

3. Quick verification

sysctl kernel.randomize_va_space
sysctl net.ipv4.conf.all.rp_filter
sysctl fs.protected_hardlinks

Confirm that the output matches the expected state before considering the intervention complete.

4. Operational notes

Apply a few changes at a time and observe the effects: writing the file is easy, managing regressions is the real work.

Quick checklist

[ ] Steps completed\n[ ] Config updated\n[ ] Tests executed\n[ ] Rollback ready\n[ ] Logs checked

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