User guide

Introduction to Network Security
6 WatchGuard Firebox X Edge
About PPPoE
Some ISPs assign their IP addresses through Point-to-Point Protocol
over Ethernet (PPPoE). PPPoE expands a standard dial-up connec-
tion to add some of the features of Ethernet and PPP. This system
allows the ISP to use the billing, authentication, and security sys-
tems of their dial-up infrastructure with DSL modem and cable
modem products.
Domain Name Service (DNS)
If you do not know the address of a person, you can frequently find
it in the telephone directory. On the Internet, the equivalent to a
telephone directory is the Domain Name Service (DNS). You use DNS
all the time, but you may not know it. When you use a “.com”
address such as www.mysite.com. www.mysite.com is the domain
name of the Web site. A special computer on your corporate net-
work or at your ISP does DNS resolution to find the IP address
which goes with the domain name. When you type the .com address
into your Internet browser, your computer gets the real IP address
from the DNS server.
A URL (Uniform Resource Locator) identifies each IP address on the
Internet. An example of a URL is:
http://www.watchguard.com/
Services
A service opens access from your network to a computer that is
external to your network. You use services to send e-mail or move
files from one computer to a different computer through the net-
work. These services use protocols. Frequently used Internet services
are:
• World Wide Web access uses Hypertext Transfer Protocol (HTTP)
• E-mail uses Simple Mail Transfer Protocol (SMTP)
• File transfer uses File Transfer Protocol (FTP)
• Changing a domain name to an Internet address uses Domain
Name Service (DNS)
• Remote terminal access uses Telnet or Secure Shell