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