D-1
Cisco Security Appliance Command Line Configuration Guide
OL-10088-01
APPENDIX
D
Addresses, Protocols, and Ports
This appendix provides a quick reference for IP addresses, protocols, and applications. This appendix
includes the following sections:
• IPv4 Addresses and Subnet Masks, page D-1
• IPv6 Addresses, page D-5
• Protocols and Applications, page D-11
• TCP and UDP Ports, page D-11
• Local Ports and Protocols, page D-14
• ICMP Types, page D-15
IPv4 Addresses and Subnet Masks
This section describes how to use IPv4 addresses in the security appliance. An IPv4 address is a 32-bit
number written in dotted-decimal notation: four 8-bit fields (octets) converted from binary to decimal
numbers, separated by dots. The first part of an IP address identifies the network on which the host
resides, while the second part identifies the particular host on the given network. The network number
field is called the network prefix. All hosts on a given network share the same network prefix but must
have a unique host number. In classful IP, the class of the address determines the boundary between the
network prefix and the host number.
This section includes the following topics:
• Classes, page D-1
• Private Networks, page D-2
• Subnet Masks, page D-2
Classes
IP host addresses are divided into three different address classes: Class A, Class B, and Class C. Each
class fixes the boundary between the network prefix and the host number at a different point within the
32-bit address. Class D addresses are reserved for multicast IP.
• Class A addresses (1.xxx.xxx.xxx through 126.xxx.xxx.xxx) use only the first octet as the network
prefix.
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