Network 101
Purpose
Configure and test common network services (HTTP, HTTPS, SNMP, SMB) for penetration testing lab environments. Enable hands-on practice with service enumeration, log analysis, and security testing against properly configured target systems.
Inputs/Prerequisites
- Windows Server or Linux system for hosting services
- Kali Linux or similar for testing
- Administrative access to target system
- Basic networking knowledge (IP addressing, ports)
- Firewall access for port configuration
Outputs/Deliverables
- Configured HTTP/HTTPS web server
- SNMP service with accessible communities
- SMB file shares with various permission levels
- Captured logs for analysis
- Documented enumeration results
Core Workflow
1. Configure HTTP Server (Port 80)
Set up a basic HTTP web server for testing:
Windows IIS Setup:
- Open IIS Manager (Internet Information Services)
- Right-click Sites → Add Website
- Configure site name and physical path
- Bind to IP address and port 80
Linux Apache Setup:
# Install Apache
sudo apt update && sudo apt install apache2
# Start service
sudo systemctl start apache2
sudo systemctl enable apache2
# Create test page
echo "<html><body><h1>Test Page</h1></body></html>" | sudo tee /var/www/html/index.html
# Verify service
curl http://localhost
Configure Firewall for HTTP:
# Linux (UFW)
sudo ufw allow 80/tcp
# Windows PowerShell
New-NetFirewallRule -DisplayName "HTTP" -Direction Inbound -Protocol TCP -LocalPort 80 -Action Allow
2. Configure HTTPS Server (Port 443)
Set up secure HTTPS with SSL/TLS:
Generate Self-Signed Certificate:
# Linux - Generate certificate
sudo openssl req -x509 -nodes -days 365 -newkey rsa:2048 \
-keyout /etc/ssl/private/apache-selfsigned.key \
-out /etc/ssl/certs/apache-selfsigned.crt
# Enable SSL module
sudo a2enmod ssl
sudo systemctl restart apache2
Configure Apache for HTTPS:
# Edit SSL virtual host
sudo nano /etc/apache2/sites-available/default-ssl.conf
# Enable site
sudo a2ensite default-ssl
sudo systemctl reload apache2
Verify HTTPS Setup:
# Check port 443 is open
nmap -p 443 192.168.1.1
# Test SSL connection
openssl s_client -connect 192.168.1.1:443
# Check certificate
curl -kv https://192.168.1.1
3. Configure SNMP Service (Port 161)
Set up SNMP for enumeration practice:
Linux SNMP Setup:
# Install SNMP daemon
sudo apt install snmpd snmp
# Configure community strings
sudo nano /etc/snmp/snmpd.conf
# Add these lines:
# rocommunity public
# rwcommunity private
# Restart service
sudo systemctl restart snmpd
Windows SNMP Setup:
- Open Server Manager → Add Features
- Select SNMP Service
- Configure community strings in Services → SNMP Service → Properties
SNMP Enumeration Commands:
# Basic SNMP walk
snmpwalk -c public -v1 192.168.1.1
# Enumerate system info
snmpwalk -c public -v1 192.168.1.1 1.3.6.1.2.1.1
# Get running processes
snmpwalk -c public -v1 192.168.1.1 1.3.6.1.2.1.25.4.2.1.2
# SNMP check tool
snmp-check 192.168.1.1 -c public
# Brute force community strings
onesixtyone -c /usr/share/seclists/Discovery/SNMP/common-snmp-community-strings.txt 192.168.1.1
4. Configure SMB Service (Port 445)
Set up SMB file shares for enumeration:
Windows SMB Share:
- Create folder to share
- Right-click → Properties → Sharing → Advanced Sharing
- Enable sharing and set permissions
- Configure NTFS permissions
Linux Samba Setup:
# Install Samba
sudo apt install samba
# Create share directory
sudo mkdir -p /srv/samba/share
sudo chmod 777 /srv/samba/share
# Configure Samba
sudo nano /etc/samba/smb.conf
# Add share:
# [public]
# path = /srv/samba/share
# browsable = yes
# guest ok = yes
# read only = no
# Restart service
sudo systemctl restart smbd
SMB Enumeration Commands:
# List shares anonymously
smbclient -L //192.168.1.1 -N
# Connect to share
smbclient //192.168.1.1/share -N
# Enumerate with smbmap
smbmap -H 192.168.1.1
# Full enumeration
enum4linux -a 192.168.1.1
# Check for vulnerabilities
nmap --script smb-vuln* 192.168.1.1
5. Analyze Service Logs
Review logs for security analysis:
HTTP/HTTPS Logs:
# Apache access log
sudo tail -f /var/log/apache2/access.log
# Apache error log
sudo tail -f /var/log/apache2/error.log
# Windows IIS logs
# Location: C:\inetpub\logs\LogFiles\W3SVC1\
Parse Log for Credentials:
# Search for POST requests
grep "POST" /var/log/apache2/access.log
# Extract user agents
awk '{print $12}' /var/log/apache2/access.log | sort | uniq -c
Quick Reference
Essential Ports
| Service | Port | Protocol |
|---|---|---|
| HTTP | 80 | TCP |
| HTTPS | 443 | TCP |
| SNMP | 161 | UDP |
| SMB | 445 | TCP |
| NetBIOS | 137-139 | TCP/UDP |
Service Verification Commands
# Check HTTP
curl -I http://target
# Check HTTPS
curl -kI https://target
# Check SNMP
snmpwalk -c public -v1 target
# Check SMB
smbclient -L //target -N
Common Enumeration Tools
| Tool | Purpose |
|---|---|
| nmap | Port scanning and scripts |
| nikto | Web vulnerability scanning |
| snmpwalk | SNMP enumeration |
| enum4linux | SMB/NetBIOS enumeration |
| smbclient | SMB connection |
| gobuster | Directory brute forcing |
Constraints
- Self-signed certificates trigger browser warnings
- SNMP v1/v2c communities transmit in cleartext
- Anonymous SMB access is often disabled by default
- Firewall rules must allow inbound connections
- Lab environments should be isolated from production
Examples
Example 1: Complete HTTP Lab Setup
# Install and configure
sudo apt install apache2
sudo systemctl start apache2
# Create login page
cat << 'EOF' | sudo tee /var/www/html/login.html
<html>
<body>
<form method="POST" action="login.php">
Username: <input type="text" name="user"><br>
Password: <input type="password" name="pass"><br>
<input type="submit" value="Login">
</form>
</body>
</html>
EOF
# Allow through firewall
sudo ufw allow 80/tcp
Example 2: SNMP Testing Setup
# Quick SNMP configuration
sudo apt install snmpd
echo "rocommunity public" | sudo tee -a /etc/snmp/snmpd.conf
sudo systemctl restart snmpd
# Test enumeration
snmpwalk -c public -v1 localhost
Example 3: SMB Anonymous Access
# Configure anonymous share
sudo apt install samba
sudo mkdir /srv/samba/anonymous
sudo chmod 777 /srv/samba/anonymous
# Test access
smbclient //localhost/anonymous -N
Troubleshooting
| Issue | Solution |
|---|---|
| Port not accessible | Check firewall rules (ufw, iptables, Windows Firewall) |
| Service not starting | Check logs with journalctl -u service-name |
| SNMP timeout | Verify UDP 161 is open, check community string |
| SMB access denied | Verify share permissions and user credentials |
| HTTPS certificate error | Accept self-signed cert or add to trusted store |
| Cannot connect remotely | Bind service to 0.0.0.0 instead of localhost |