Linux User Management Scripts

A collection of bash scripts for Linux system administration, focusing on user account management, monitoring, and remote command execution.

📋 Scripts Overview

User Account Management Scripts

add-local-user.sh

Creates a new user account with an automatically generated password.

Features:

• Requires superuser privileges
• Generates secure random passwords
• Forces password change on first login
• Displays username, password, and hostname

Usage:

sudo ./add-local-user.sh USERNAME [COMMENT]

Example:

sudo ./add-local-user.sh jsmith "John Smith - Developer"

disable-local-user.sh

Disables, deletes, and/or archives user accounts on the local system.

Features:

• Multiple operation modes (disable, delete, archive)
• Protection against system account deletion (UID < 1000)
• Optional home directory archiving
• Bulk user processing

Options:

• -d - Delete accounts instead of disabling
• -r - Remove home directory when deleting
• -a - Create archive of home directory

Usage:

sudo ./disable-local-user.sh [-dra] USERNAME [USERNAME2...]

Example:

# Disable a user
sudo ./disable-local-user.sh jsmith

# Delete user and remove home directory
sudo ./disable-local-user.sh -d -r jsmith

# Archive home directory then delete
sudo ./disable-local-user.sh -a -d jsmith

Remote Execution Script

run-anywhere.sh

Executes commands on multiple remote servers via SSH.

Features:

• Dry run mode for testing
• Verbose output option
• Custom server list file
• Sudo support for remote commands
• Error handling and reporting

Options:

• -f FILE - Specify custom server list file (default: /vagrant/servers)
• -n - Dry run (display commands without executing)
• -s - Execute with sudo on remote servers
• -v - Verbose mode (show server names)

Usage:

./run-anywhere.sh [-f FILE] [-nsv] COMMAND

Example:

# Check uptime on all servers
./run-anywhere.sh uptime

# Update package lists with sudo
./run-anywhere.sh -s "apt update"

# Dry run with verbose output
./run-anywhere.sh -n -v "hostname"

Security Monitoring Script

show-attackers.sh

Analyzes login attempts and identifies potential attackers based on failed login counts.

Features:

• Parses system log files for failed login attempts
• Groups failures by IP address
• Provides geolocation information
• Configurable threshold for alerts

Requirements:

• geoiplookup command (install with: apt install geoip-bin)
• System log file with authentication entries

Usage:

./show-attackers.sh LOG_FILE

Example:

./show-attackers.sh /var/log/auth.log

Output:

Count, IP, Location
15, 192.168.1.100, United States
12, 10.0.0.50, Unknown

📦 Prerequisites

• Linux system (CentOS/RHEL 7+ recommended)
• Root/sudo access for user management operations
• SSH access configured for remote execution scripts
• geoiplookup command (for show-attackers.sh)

🔧 Installation

1. Clone the repository:

git clone https://github.com/uv012/linux-user-management-scripts.git
cd linux-user-management-scripts

2. Make scripts executable:
```bash
chmod +x *.sh

3. For run-anywhere.sh, create a servers file:

echo "server1.example.com" > /vagrant/servers
echo "server2.example.com" >> /vagrant/servers

🔒 Security Considerations

• All user management scripts require root privileges
• Passwords are displayed only once during account creation
• System accounts (UID < 1000) are protected from deletion
• SSH connections use timeout to prevent hanging
• Scripts include error handling and validation

⚠️ Error Handling

• Each script includes comprehensive error checking:
• Input validation
• Privilege verification
• Command execution status checking
• Meaningful error messages
• Appropriate exit codes

🤝 Contributing

Feel free to submit issues and enhancement requests!

📜 License

This project is open source and available under the MIT License.