network-101 — Claude Code skill: lab network services, setup

---
name: network-101
description: 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.
metadata:
  author: zebbern
  version: "1.1"
---

# 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 |