The Study And Design Of Operating System Level Firewall

Operating system is the only software close to hardware, its security function is the basis of other software'security function. If lack for this basis, the application system and security system based on it ,for example PKI,encryption and decryption technology will not get essential guarantee. Nowadays, network security problems getting worse and worse, the demand for secure operating system is in impendence. With its wide appliance, Linux Operating System's security problems have attracted much attention. In fact, current Linux Operating System has many security problems such as too simple access control,too many root privilege and lack in process protection. This project forwards the scheme of operating system level firewalls, improving the security of Linux operating system from the angle of enhancing operating system access control. Operating system level firewalls and Linux' original access control form dual access control protection to Linux operating system. In the paper, the theory of access control,the concept of system call,the mechanism of loadable module and multiple security strategy framework--GFAC are introduced in emphasis. The paper also introduce particularly the architecture,function components,design and implementation of operating system firework and its each component' design and implementation. Because operating system firewall is implemented as a Linux loadable module, this system differs from other secure operating system in that this system does not modify Linux kernel source codes directly and this system is prone to expand, so this system has the strong points: easy to upgrade,flexible to load and fine expansibility.