ModSecurity is an embeddable web application firewall, which means it can be deployed as part of your existing web server infrastructure (Apache, IIS7 and Nginx).

This deployment method has certain advantages:

1. No changes to existing network. It only takes a few minutes to add ModSecurity to your existing web servers. And because it was designed to be completely passive by default, you are free to deploy it incrementally and only use the features you need. It is equally easy to remove or deactivate it should decide you don't want it any more.
2. No single point of failure. Unlike with network-based deployments, you will not be introducing a new point of failure to your system.
3. Implicit load balancing and scaling. Because it works embedded in web servers, ModSecurity will automatically take advantage of the additional load balancing and scalability features. You will not need to think of load balancing and scaling unless your existing system needs them.
4. Minimal overhead. Because it works from inside the web server process there is no overhead for network communication and minimal overhead in parsing and data exchange.
5. No problem with encrypted or compressed content. Many IDS systems have difficulties analysing SSL traffic. This is not a problem for ModSecurity because it is positioned to work when the traffic is decrypted and decompressed.

ModSecurity is known to work well on a wide range of operating systems. Our customers are successfully running it on Linux, Windows, Solaris, FreeBSD, OpenBSD, NetBSD, AIX, Mac OS X, and HP-UX.