Operating System Does (Internal and External Security)

 Internal Security:

 

Internal security can be thought of as a way to protect the computer’s resources from the programs concurrently running on the system. Most operating systems set programs running natively on the computer’s processor. That brings on the problem of how to stop
these programs from doing the same task and having the same privileges as the operating system which is just a program too.
Processors used for general purpose operating systems are automatically blocked from using certain hardware instructions such as those to read or write from external devices like disks. Instead, they have to ask the privileged program, or operating system kernel) to read to write. The operating system, therefore, gets the chance to check the program’s identity and allow or refused the request.


An alternative strategy available in systems that don’t meet pre- set requirements is the operating will not run user programs as native code. Instead, they either emulate a processor or provide a host for a “p-Code” based system such as Java.


Internal security is especially important with multi-user systems as it allows each user of the system to have private files that the other users cannot tamper with or read.

External Security:

Typically, an operating system offers various services to other network computers and users. These services are usually provided through ports or numbered access points beyond the operating
systems network address. These services include offerings such as file sharing, print services, e-mail, web sites, and file transfer protocols (FTP).

At the front line of security are hardware devices known as firewalls. At the operating system level, there are a number of software firewalls available. Most modern operating systems include a software firewall which is enabled by default.


A software firewall can be configured to allow or deny network traffic to or from a service or application running on the operating system. Therefore, one can install and be running an insecure service such as Telnet or FTP and not have to be threatened by a security breach because the firewall would deny all traffic trying to connect to the service on that port.