Basic Setup - First 5 minutes on a new server

• Copy SSH ID: ssh-copy-id
• Update server: sudo apt update; sudo apt upgrade
• Firewall:
  • apt install ufw
  • ufw allow ssh
  • ufw enable
• Reboot server: reboot
• Install mosh:
  • apt install mosh
  • ufw allow 60000:61000/udp
  • ufw enable
• Create new user:
  • adduser tom
  • usermod -aG sudo tom
• Add server to local SSH config and give it a name.
• Reconnect to server: mosh name
• Install vim: sudo apt install vim
• Configure default editor: update-alternatives --config editor
• Lock the root account to disable root login: sudo passwd -l root

Preference is security, not availability.

• Unattended upgrades: sudo apt install unattended-upgrades
• Fail2ban: sudo apt install fail2ban
• Restart each week: sudo crontab -e
  • 5 3 * * 1 reboot

Postfix as mailforwarder:

• Install postfix: sudo apt install postfix
• Choose internet with smart host
• Choose your domain name
• Choose the SMTP server
• Install sasl support: sudo apt install libsasl2-modules
• Edit /etc/postfix/main.cf:
  • Before relayhost:

smtp_sasl_auth_enable = yes
smtpd_sasl_auth_enable = yes
smtp_sasl_security_options = noanonymous
smtp_sasl_tls_security_options = noanonymous
smtp_sasl_password_maps = hash:/etc/postfix/smtp_auth
smtp_tls_security_level = encrypt
smtp_tls_note_starttls_offer = yes

• Create the mentioned /etc/postfix/smtp_auth with the following content:
  • mail.server.com user:passwort
• Create the db file: sudo postmap /etc/postfix/smtp_auth
• Delete the input file: sudo rm /etc/postfix/smtp_auth
• Rename the senders: sudo vim /etc/postfix/generic with the following content:
  • @hostname your@sender.address
• Restart postfix server: sudo systemctl restart postfix

Test postifx:

• Install mail command: sudo apt install mailutils

• Send test mail: mail -s "test" thomas@irgang.eu < /dev/null

• Watch logs: journalctl -f and check mail inbox

• Install useful tools: sudo apt install vim git tmux htop ripgrep python3 python3-venv

• Install docker and docker compose:

  • sudo apt install docker.io docker-compose docker-cli docker-buildx
  • sudo usermod -aG docker your_user