1. GFI LanGuard
GFI LanGuard is an award winning network security and port scanning tool, which scans your business network and ports to detect, assess and correct security vulnerabilities. GFI LanGuard provides fast TCP & UDP port scanning & identification, as well as over 50,000 vulnerability assessments, including OVAL and SANS Top 20.
New security holes are automatically detected with scheduled comparisons of port scan results. Another great feature includes its assets inventory, which enables you to find network devices that you were not aware of. GFI LanGuard is one complete network security package that combines port scanning, patch management, vulnerability assessment and network auditing.