LinuxAdvanced TopicsSystem Administration

System Administration

Learn about Linux system administration, system configuration, and maintenance.

System Administration

System administration in Linux involves managing system resources, users, services, and system configuration. This guide covers essential aspects of Linux system administration.

User Management

User Commands

useradd  # Add new user
usermod  # Modify user
userdel  # Delete user
passwd   # Change password

Group Management

groupadd # Add new group
groupmod # Modify group
groupdel # Delete group
gpasswd  # Change group password

Package Management

Package Managers

  1. Debian/Ubuntu

    apt update
apt install package
apt remove package

  2. RHEL/CentOS

    yum update
yum install package
yum remove package

  3. Arch Linux

    pacman -Syu
pacman -S package
pacman -R package

Service Management

System Services

systemctl start service    # Start service
systemctl stop service     # Stop service
systemctl restart service  # Restart service
systemctl status service   # Check service status

Service Configuration

systemctl enable service   # Enable service at boot
systemctl disable service  # Disable service at boot
systemctl reload service   # Reload service configuration

System Monitoring

Resource Monitoring

top      # Process monitoring
htop     # Interactive process viewer
vmstat   # Virtual memory statistics
iostat   # I/O statistics

System Information

uname    # System information
df       # Disk space usage
free     # Memory usage
lscpu    # CPU information

System Configuration

Network Configuration

# Network interface configuration
ifconfig
ip addr
# Network service configuration
systemctl status NetworkManager

System Time

# Time synchronization
timedatectl status
# NTP configuration
systemctl status chronyd

System Maintenance

System Updates

# Update system packages
apt update && apt upgrade  # Debian/Ubuntu
yum update                 # RHEL/CentOS
pacman -Syu               # Arch Linux

System Cleanup

# Clean package cache
apt clean                 # Debian/Ubuntu
yum clean all            # RHEL/CentOS
pacman -Sc               # Arch Linux
 
# Clean temporary files
rm -rf /tmp/*

Security Administration

Firewall Configuration

# UFW (Ubuntu)
ufw enable
ufw allow ssh
ufw status
 
# Firewalld (RHEL/CentOS)
firewall-cmd --list-all
firewall-cmd --add-service=ssh

Security Monitoring

# Log monitoring
tail -f /var/log/auth.log
# Security scanning
lynis audit system

Backup and Recovery

Backup Tools

# File backup
tar -czf backup.tar.gz /path/to/backup
# System backup
dd if=/dev/sda of=/backup/system.img

Recovery Procedures

  1. System Recovery

    • Boot from live media
    • Mount system partition
    • Restore from backup

  2. Data Recovery

    • Use recovery tools
    • Check file systems
    • Restore from backup

System Logs

Log Files

Common log files:

  • /var/log/syslog: System logs
  • /var/log/auth.log: Authentication logs
  • /var/log/apache2/: Web server logs
  • /var/log/mysql/: Database logs

Log Management

# View logs
tail -f /var/log/syslog
# Rotate logs
logrotate -f /etc/logrotate.conf

Best Practices

  1. System Administration

    • Regular updates
    • Backup procedures
    • Security monitoring
    • Performance tuning

  2. User Management

    • Strong passwords
    • Regular audits
    • Access control
    • User monitoring

  3. Service Management

    • Service dependencies
    • Resource limits
    • Monitoring
    • Documentation

Next Steps

Continue learning about:

  • Advanced system administration
  • System hardening
  • Performance optimization
  • Disaster recovery
  • System automation
Shell ScriptingSecurity