Objective
Perform a comprehensive security audit of network devices such as routers and switches. Identify potential vulnerabilities, apply security best practices, and verify access control policies to ensure proper authentication and device security.
Scenario
As a network administrator, it is crucial to ensure that all network devices are configured securely to prevent unauthorized access and network breaches. In this exercise, you’ll audit a router or switch, identify security weaknesses, and implement best practices for hardening the device.
⚠️ Important: Perform this exercise in a controlled and authorized environment. Unauthorized access to network devices is illegal and unethical.
Lab Instructions
Step 1: Access the Network Device
a. Connect via SSH or Console
- For SSH access:
ssh admin@<device-ip>
- For console access, use a terminal emulator like PuTTY or Minicom.
b. Enter Privileged EXEC Mode (Cisco Example)
enable
Step 2: Perform Baseline Configuration Review
a. Review the Running Configuration
show running-config
- Check for:
- Default or weak passwords.
- Unused or unnecessary services enabled.
- Open and unused ports.
- Lack of encryption for management access.
b. Identify Open Ports and Services
show ip interface brief
show control-plane host open-ports
c. Review User Accounts and Access Levels
show users
show running-config | include username
Step 3: Identify Security Vulnerabilities
- Weak Passwords: Default or simple passwords.
- Outdated Firmware: Check firmware version:
show version
- Open Management Interfaces: Open Telnet/HTTP access.
- Unsecured Remote Access: Lack of SSH or encrypted management protocols.
Step 4: Apply Security Best Practices
a. Enforce Strong Password Policies
username admin secret StrongPass!2024
- Use complex passwords with uppercase, lowercase, numbers, and symbols.
b. Disable Unused Services
no service finger
no ip http server
no ip http secure-server
c. Enable SSH and Disable Telnet
line vty 0 4
transport input ssh
no transport input telnet
ip domain-name example.com
crypto key generate rsa
d. Implement Access Control Lists (ACLs)
access-list 10 permit 192.168.1.0 0.0.0.255
line vty 0 4
access-class 10 in
e. Update Device Firmware
- Check the vendor’s website for the latest firmware.
- Follow device-specific instructions to apply updates.
f. Enable Logging and Monitoring
logging buffered 10000
logging console
Step 5: Test Access Control Policies
a. Verify SSH Access
- Attempt to log in with authorized and unauthorized accounts.
- Confirm that only permitted IPs can access the device.
b. Check for Disabled Services
- Ensure Telnet, HTTP, and other unnecessary services are disabled.
c. Monitor Logs for Unauthorized Attempts
show logging
Solution & Explanation
Why Network Device Security is Important
- Routers and switches are critical infrastructure devices that, if compromised, can lead to data breaches and network outages.
Common Vulnerabilities
- Default or weak passwords.
- Outdated firmware.
- Unnecessary open ports and services.
- Lack of encrypted communication.
Security Best Practices
- Strong Passwords: Implement complex passwords and regular password changes.
- Encrypted Access: Use SSH instead of Telnet for remote management.
- Firmware Updates: Regularly update device firmware.
- Access Control: Limit management access using ACLs.
- Disable Unused Services: Reduce the attack surface.
- Logging: Enable logging to monitor device activity.
Testing & Verification
- SSH Access: Confirm SSH access works and Telnet is disabled.
- ACLs: Verify that only authorized IPs can access the device.
- Logs: Check logs for suspicious activities.
Security Best Practices
- Change Default Credentials: Replace factory-set usernames and passwords.
- Use Encrypted Protocols: Always use SSH, HTTPS, and SNMPv3.
- Implement ACLs: Limit access based on IP addresses.
- Disable Unused Ports/Services: Close unnecessary services.
- Enable Logging and Alerts: Monitor devices for unusual behavior.
- Regularly Audit Devices: Perform routine security audits.
Additional Script (Optional)
Automate basic security hardening for network devices:
#!/bin/bash
# Basic Network Device Hardening Script
# Set strong password
username admin secret StrongPass!2024
# Disable unnecessary services
no service finger
no ip http server
no ip http secure-server
# Enable SSH
ip domain-name example.com
crypto key generate rsa modulus 2048
line vty 0 4
transport input ssh
no transport input telnet
# Enable logging
logging buffered 10000
logging console
echo "Basic security hardening applied."
Conclusion
In this exercise, you performed a security audit of a network device, identified vulnerabilities, and implemented best practices for securing routers and switches. Regular audits and continuous monitoring are critical for maintaining secure network infrastructure and preventing unauthorized access.
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