TCP/IP Firewall

The combined set of protocols is called the Transmission Control Protocol and Internet Protocol TCP/IPprotocol suite.

As a network administrator, it is important that you understand the nature of potential attacks on computer security. We'll briefly describe the most important types of attacks so that you can better understand precisely what the Linux IP firewall will protect you against. You should do some additional reading to ensure that you are able to protect your network against other types of attacks. Here are some of the more important methods of attack and ways of protecting yourself against them:

Unauthorized access
This simply means that people who shouldn't be allowed to use your computer services are able to connect to and use them. For example, people outside your company might try to connect to your company accounting host or to your NFS server.
There are various ways to avoid this attack by carefully specifying who can gain access through these services. You can prevent network access to all except the intended users.


A malicious person who gains access to a computer system may guess system passwords or exploit the bugs and idiosyncratic behavior of certain programs to obtain a working account on that host.