Agent skill

Network 101

This skill should be used when the user asks to "set up a web server", "configure HTTP or HTTPS", "perform SNMP enumeration", "configure SMB shares", "test network services", or needs guidance on configuring and testing network services for penetration testing labs.

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Metadata

Additional technical details for this skill

author
zebbern
version
1.1

SKILL.md

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:

  1. Open IIS Manager (Internet Information Services)
  2. Right-click Sites → Add Website
  3. Configure site name and physical path
  4. Bind to IP address and port 80

Linux Apache Setup:

bash
# 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:

bash
# 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:

bash
# 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:

bash
# 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:

bash
# 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:

bash
# 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:

  1. Open Server Manager → Add Features
  2. Select SNMP Service
  3. Configure community strings in Services → SNMP Service → Properties

SNMP Enumeration Commands:

bash
# 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:

  1. Create folder to share
  2. Right-click → Properties → Sharing → Advanced Sharing
  3. Enable sharing and set permissions
  4. Configure NTFS permissions

Linux Samba Setup:

bash
# 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:

bash
# 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:

bash
# 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:

bash
# 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

bash
# 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

bash
# 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

bash
# 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

bash
# 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

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