Week 4 Unix Security - Physical Security

Security is one of the most important things to consider when your computer is hooked up to a network. It is very important that there are no unwanted users on your network. Some unwanted users intend to do no harm, while others will want to damage your system or take your information. This paper's purpose is to discuss security on Unix systems. The sections will focus on physical security, network security, account security, and file system security (Unix Tools, 2008).

Physical Security

Physical security is the first step at securing a system, yet it is often times overlooked. Physical security is what you would do to keep your actual system safe. One of the easiest ways to get information from a system is to walk up to it and use it, or to steal it. The computer needs to be in a place that cannot be accessed by others. A computer is not necessarily secure when you turn it off. Even if it is password protected, someone could be able to turn on the computer and interrupt the boot process. This can get access to the root user, and if the root password is not very strong, the intruder can guess it giving them access to the system. Systems (severs especially) should be in a secure room that few people have access to. If the company is big enough and the information is sensitive enough (ie government agencies) there can even be around the clock security guards protecting these secure rooms.

Another aspect of physical security is data security. Companies should be sure to have onsite back up disk in case of downtime, as well as a back up disk that is at an off site location. These disks should be in a locked container, and only authorized personnel would have the key.

The last thing to consider with physical security is users being responsible. All users should make sure to log out of their system when they are not at their desks. They should also be sure to use a strong password that uses a combination of upper/lowercase and numbers. The user should never have any passwords or hits written down.

Network Security

You have to make sure to keep unwanted users out of your system. Once you are connected to any network, it increases the number of people that would be able to get on to your system. The act of keeping unwanted users from being on the network is filtering. It is important for networks to have routers with firewall capabilities. When the firewall is at the router level, any unwanted activity coming from the outside is stopped fairly early on.

Another thing that a router can do for the Unix network is to prevent spoofing. A packet of information can imitate a host on the network by using the same host name. A way to make sure that this does not happen is to turn off source routing on the router. Once it is off, a filter can be applied that makes sure that packets coming from the outside do not have a source IP that is the same as inside the network. This means that another machine cannot pretend to be a trusted host.

Account Security

As mentioned earlier, passwords are important for security purposes. It is not only up to the user, but the network administrator to make sure that all accounts have an un-guessable password. The administrator