1) To determine your IP address, issue the command:
the output will show a list of interfaces. If you have 1 Ethernet interface, you will see entries for Eth0, if you have 2 interfaces, you will see entries for Eth0 and Eth1. Both interfaces will have an IP address associated with them in the list of info. You will also see an "dummy" or loopback interface lo0, associated with address 127.0.0.1, which is the address applications need to use when sending data to other applications on the same machine.
2)to find your hostname, issue the command:
3) firewalls are built into the kernel in Linux, so all you need is to either know the commands for the kernel, or because that is pretty hard first time round, you can use a firewall manager. A good CLI-based one is "Shorewall", ( http://www.shorewall.net
) and very nice Gui-based one is "Firestarter" ( http://www.fs-security.com/
)...Ultimately, they all control IPTABLES (http://www.netfilter.org/
) functions in the kernel
That's a pretty basic answer, post more details if you can be more specific about what you are trying to do