# What are shadow perimeters in industrial environments?

Shadow perimeters refer to undocumented or unauthorised connections that bypass established security boundaries, such as rogue cellular modems or vendor-installed wireless access points. These connections create invisible entry points into the operational technology network, circumventing firewalls and monitoring tools. To maintain a secure posture, organisations must perform physical and logical audits to identify and secure these hidden entry points. Learn more about [securing boundaries in our strategic blueprint](https://www.agilicus.com/white-papers/industrial-cyber-security-best-practices/).

For more information, see [Industrial Cyber Security Best Practices](https://www.agilicus.com/white-papers/industrial-cyber-security-best-practices/).