Firewall Systems

You can set up a firewall system to protect the resources in your network from outside access. A firewall system is a secure host that acts as a barrier between your internal network and outside networks. The internal network treats every other network as untrusted. You should consider this setup as mandatory between your internal network and any external networks, such as the Internet, with which you communicate.

A firewall acts as a gateway and as a barrier. As a gateway, it passes data between the networks. As a barrier, it blocks the free passage of data to and from the network. A user on the internal network must log in to the firewall system to access hosts on remote networks. Similarly, a user on an outside network must first log in to the firewall system before being granted access to a host on the internal network.

A firewall can also be useful between some internal networks. For example, you can set up a firewall or a secure gateway computer to restrict the transfer of packets by address or by protocol. You could then allow packets for transferring mail but not allow packets for the ftp command.

In addition, all electronic mail that is sent from the internal network is first sent to the firewall system. The firewall then transfers the mail to a host on an external network. The firewall system also receives all incoming electronic mail, and distributes the mail to the hosts on the internal network.

A firewall system should not have any trusted hosts. A trusted host is a host from which a user can log in without being required to supply a password. A firewall system should not share any of its file systems, or mount any file systems from other servers.

IPsec and the IP Filter feature of Oracle Solaris can provide firewall protection. For more information about protecting network traffic, see Securing the Network in Oracle Solaris 11.2 .