Introduction
When you’re handed the keys to a virtual machine (VM) without documentation — no network diagrams, no SOPs, no nothing — it’s like walking into a datacenter blindfolded. This post shows how you can quickly profile the system, identify critical configurations, assess security posture, and inventory applications using a systematic Bash script.
Reality Check
Note: Many organizations restrict root access, direct file system scans, or bulk configuration dumps — for valid security reasons. The level of access this script assumes is often only available in lab, dev, or smaller org setups. Always check with your security team before running such scripts in production.
1. Identify the Landscape
Start with basic VM profiling:
- Hostname and OS details
- Memory, disk, and root access check
- SSH status
Script Insight:
hostname
cat /etc/*release
free -h
df -h /
ss -tuln | grep :22
2. Who’s Been Here Before?
Audit all user accounts, last login times, shells, and home directories. Look for any dormant or suspicious accounts.
Example:
getent passwd
lastlog
3. Explore User Environments
Understand user behavior:
- Shell aliases
- Environment variables
- SSH keys and known hosts
These give clues about frequently used tools and remote access patterns.
4. Inventory What’s Installed
Identify packages, services, and manually installed software:
- Use
dpkg,rpm, orsystemctl - Parse command histories (
.bash_history) for install commands
This is especially useful for recreating environments or detecting manual tweaks.
5. Configuration Files and Services
Look for:
- Config files in
/etc/ - VPN, firewall, and SSH configs
- Cron jobs and auto-start services
You’ll find both intended and legacy configurations here — some of which may need cleanup.
6. Web and Network Stack
Check for:
- Listening ports
- Apache/Nginx server blocks
- Docker or Podman containers
- SSL certificate locations and expiration
This helps identify publicly accessible apps and how traffic is routed.
7. Infrastructure Components
The script scans for:
- Kubernetes clusters
- LXD/LXC containers
- Logging/monitoring tools
- Configuration management (Chef, Puppet)
Knowing what’s managing what saves hours of troubleshooting.
8. Security Concerns
Flag large files, git repos, and potentially suspicious processes. Also, look for:
- SSO systems (LDAP, Okta, Kerberos)
- Cloud credentials or SDK configs (AWS, GCP, Azure)
Conclusion: Structure Before Strategy
Once you’ve mapped out the VM, only then can you:
- Triage security risks
- Design automation
- Implement monitoring
- Apply hardening steps
Final Tip
Turn this script into an Ansible playbook or systemd timer to periodically snapshot system state — especially in dev/test VMs.
