Network services are common services you can expect to find on just about any network. These typically include:
- WINS (legacy; less common today)
- Authentication/Directory Services
- File and print
- Remote Access
Nearly all network services have been vulnerable to attack at some point or another. Usually the vulnerability lies with the specific product or implementation. In some cases, however, the vulnerability lies less with the server and more with the process itself. For example, DHCP is broadcast-based with no authentication. This means a rogue DHCP server handing out incompatible IP addresses would be very disruptive to a network. When scanning network services, you can use a good general vulnerability scanner. If your network has unusual services, you might have to use a specialized tool.
Note: Do not confuse network service with network device. A network service provides client services. A network device such as a router or switch connects devices and moves traffic along the network.