文档介绍：Introducing ACL Operation
Access Control Lists
Outline
Overview
ACL Overview
ACL Applications
Types of ACLs
ACL Operations
ACL Statement Processing
Wildcard Masking Process
Summary
Why Use ACLs?
Filtering过滤: Manage IP traffic by filtering packets passing through a router
Classification分类: Identify traffic for special handling
ACL Applications: Filtering
Permit or deny packets moving through the router.
Permit or deny vty access to or from the router.
Without ACLs, all packets could be transmitted to all parts of work.
ACL Applications: Classification
定义被保护的流量
定义被过滤的路由选择更新
定义需要转换的地址
Special handling for traffic based on packet tests
Types of ACLs
Standard ACL标准列表: (1-99)
检查数据包的源地址
一旦应用会对所有的协议调用
Extended ACL扩展列表: (100-199)
检查数据包的源地址和目的地址
对特定的某些协议某些端口进行调用
Named ACL: standard and extended ACLs:
Numbered ACLs use a number for identification
Named ACLs use a descriptive name or number for identification
How to Identify ACLs
Numbered standard IPv4 lists (1–99) test conditions of all IP packets for source addresses. Expanded range (1300–1999).
Numbered extended IPv4 lists (100–199) test conditions of source and destination addresses, specific TCP/IP protocols, and destination ports. Expanded range (2000–2699).
Named ACLs identify IP standard and extended ACLs with an alphanumeric string (name).
标准ACL 的工作原理
出站访问列表的工作原理
Wildcard Bits: How to Check the Corresponding Address Bits
0 means to match the value of the corresponding address bit
1 means to ignore the value of the corresponding address bit