User guide

Introduction to Network Security
4 Firebox X Edge e-Series
This table shows common network masks and their equivalents in slash notation.
About entering IP addresses
When you type IP addresses in the Quick Setup Wizard or dialog boxes in Firebox management software, type
the digits and periods in the correct sequence. Do not use the TAB key, arrow key, spacebar, or mouse to put
your cursor after the periods.
For example, if you type the IP address 172.16.1.10, do not type a space after you type 16. Do not try to put
your cursor after the subsequent period to type 1. Type a period directly after 16, and then type 1.10. Press the
slash (/) key to move to the netmask.
Static and dynamic IP addresses
ISPs (Internet service providers) assign an IP address to each device on their network. The IP address can be
static or dynamic.
A static IP address is an IP address that always stays the same. If you have a web server, FTP server, or other
Internet resource that must have an address that cannot change, you can get a static IP address from your ISP.
A static IP address is usually more expensive than a dynamic IP address, and some ISPs do not supply static IP
addresses. You must configure a static IP address manually.
A dynamic IP address is an IP address that an ISP lets you use temporarily. If a dynamic address is not in use, it
can be automatically assigned to a different device. Dynamic IP addresses are assigned using either DHCP
or PPPoE.
About DHCP
Dynamic Host Configuration Protocol (DHCP) is an Internet protocol that computers on a network use to get
IP addresses and other information such as the default gateway. When you connect to the Internet, a
computer configured as a DHCP server at the ISP automatically assigns you an IP address. It could be the same
IP address you had before, or it could be a new one. When you close an Internet connection that uses a
dynamic IP address, the ISP can assign that IP address to a different customer.
You can configure the Firebox as a DHCP server for networks behind the Firebox. You assign a range of
addresses that the DHCP server can choose from.
About PPPoE
Some ISPs assign their IP addresses through Point-to-Point Protocol over Ethernet (PPPoE). PPPoE expands a
standard dial-up connection to add some of the features of Ethernet and PPP. This network protocol allows
the ISP to use the billing, authentication, and security systems of their dial-up infrastructure with DSL modem
and cable modem products.
Network mask Slash equivalent
255.0.0.0 /8
255.255.0.0 /16
255.255.255.0 /24
255.255.255.128 /25
255.255.255.192 /26
255.255.255.224 /27
255.255.255.240 /28
255.255.255.248 /29
255.255.255.252 /30