1. Update existing packages
apt-get update && apt-get upgrade
apt autoremove && apt clean
2. Secure SSH
> sudo nano /etc/ssh/ssd_config
Port 29
PermitRootLogin prohibit-password
PubkeyAuthentication yes
3. Enable UWF
> sudo nano /etc/default/ufw
IPV6=yes
Then run:
sudo ufw default deny incoming
sudo ufw default allow outgoing
sudo ufw allow 29
sudo ufw enable
sudo ufw status numbered
4. Enable SWAP
Check what is enabled:
sudo swapon --show
free -h
Create SWAP:
sudo fallocate -l 2G /swapfile
sudo chmod 600 /swapfile
sudo mkswap /swapfile
sudo swapon /swapfile
ls -lh /swapfile
Make changes permanent:
sudo cp /etc/fstab /etc/fstab.bak
echo '/swapfile none swap sw 0 0' | sudo tee -a /etc/fstab
> sudo nano /etc/sysctl.conf
vm.swappiness=10
vm.vfs_cache_pressure=50
Check again:
cat /proc/sys/vm/swappiness
cat /proc/sys/vm/vfs_cache_pressure
5. Set correct timezone
dpkg-reconfigure tzdata