Network configuration

GNS3 | Network software emulator

The network topology was setup and configured using the Graphical Network Simulator 3 (GNS3) application. Using GNS3 networking devices can be emulated to create complex networks. Many corporations such as Walmart, AT&T, and NASA use GNS3 for testing network configurations before applying them in the real world. GNS3 is renowned in the computer networking field for being reliable as well as feature-rich. It is open-source and can be obtained for free at https://www.gns3.com/.

Appliances

Each device in GNS3 is known as an appliance. These appliances represent the virtual devices running in the topology. Below is a list of each device and operating systems that were used in the topology.

3x Cisco IOSv 15.7(3) routers
1x Cisco IOSvL2 15.2.1 switch
1x Kali Linux 2021.1 PC (PC – A)
1x Ubuntu 20.10 PC (PC – B)
1x Ubuntu Server 18.04.3 (PC – C)

IP address scheme

Device configuration

Cisco routers

Interfaces were configured per the above IP addressing scheme. Any unused ports were shutdown to ensure security. Banners were applied to enforce unauthorized access policies. An admin user was created and passwords were encrypted using the scrypt hashing algorithm. A domain name of SnrProj.com was set and SSH access was configured to allow local login.

OSPF was implemented as the routing protocol using the area ID of 0. OSPF authentication was also configured to establish trust within the network configuration.

After penetration testing was performed more security measures were implemented to prevent further attacks.

Cisco switch

The VLANs were configured per the above IP addressing scheme. All unused ports were shutdown and switchport port-security was thoroughly impended on each used interface. The interfaces were configured to only allow 1 MAC address and was set to cache the address. Ports were set to shutdown immediately if a policy violation occurs.

Ubuntu server

Before configuration began on the Ubuntu server, the system was updated. A temporary internet connection was given to the machine to complete the updates. The host was then statically assigned per the above IP addressing scheme. The Ubuntu server was directly connected to G0/1 on the switch and was hosted in VLAN10.

Apache2 was installed and is used to host the web services. The website was accessible from all external sources via the IP address of the system. To further simulate a rea-world attack, a domain name for the website was configured.

Finally, Very Secure File Transfer Protocol Daemon (VSFTPD) version 2.3.4 was specifically installed for The Metasploit Framework attack.

Ubuntu desktop

Internet access was given to the system in order to complete system updates. The host was statically assigned per the above IP addressing scheme and was directly connected to G1/0 on the switch. Access to VLAN20 was configured on this interface. Next, an FTP user was created and VSFTPD version 3.0.3 was installed.

The system's host file was modified to resolve the Ubuntu server's domain name to the correct IP address.

Kali Linux

The host was statically assigned per the above IP addressing scheme. The Kali Linux system was directly connected to the attack router on G0/1. All the programs required for the penetration test came pre-installed. No updates or additional programs were installed.