Chapter 5 - ACLs docx

Học viện mạng Bach Khoa - Website: www.bkacad.com 14STANDARD ACLs... Học viện mạng Bach Khoa - Website: www.bkacad.com 27Standard ACLs to Control Telnet/SSH... Học viện mạng Bach Khoa -

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Chapter 5 - ACLs

CCNA Exploration 4.0

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Học viện mạng Bach Khoa - Website: www.bkacad.com 2

What is an ACL ?

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Packet Filtering OSI Model

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ACL Configuration Guidelines

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ALC – 3P

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ACL Direction

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ACL Direction

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ACL Operation

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What is an ACL ?

• ACLs perform the following tasks:

1 Limit network traffic to increase network performance For example, if

corporate policy does not allow video traffic on the network, ACLs that

block video traffic could be configured and applied This would greatly

reduce the network load and increase network performance

2 Provide traffic flow control ACLs can restrict the delivery of routing

updates If updates are not required because of network conditions,

5 Control which areas a client can access on a network

6 Screen hosts to permit or deny access to network services ACLs can

permit or deny a user to access file types, such as FTP or HTTP.

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Where to place ACLs

1 Use ACLs in firewall routers positioned between your internal network and an external network such as the Internet

2 Use ACLs on a router positioned between two parts of your network to control traffic entering or exiting a specific part of your internal network

3 Configure ACLs on border routers-routers situated at the edges of your networks

This provides a very basic buffer from the outside network, or between a less

controlled area of your own network and a more sensitive area of your network

4 Configure ACLs for each network protocol configured on the border router interfaces You can configure ACLs on an interface to filter inbound traffic, outbound traffic, or both.

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ACL Best Practices

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Types of Cisco ACLs

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Numbering and Naming ACLs

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STANDARD ACLs

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How a Standard ACL works ?

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Configuring a Standard ACL

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Configuring Standard ACL

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Standard ACL Command Syntax

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Procedure for Configuring Standard ACLs

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ACL Wildcard Masking

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Wildcard Bit Mask Keywords

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Wildcard Bit Mask Keywords

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Documenting an ACL

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Standard ACL Examples

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Standard ACLs to Control Telnet/SSH

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Standard Named ACLs

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Verifying ACLs

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Removing an ACL

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Editing Numbered ACLs

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Editing Named ACLs

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EXTENDED ACLs

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Extended ACL Flow

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Extended ACLs

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Configuring Extended ACLs

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Extended ACL Command Syntax

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TCP Ports

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TCP Ports

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TCP Conversation

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TCP Conversation

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UDP Ports

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Applying Extended ACLs to Interfaces

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Extended ACLs Examples

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Extended ACLs Examples

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Named Extended ACLs

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ACL Practise

• Inside network can ping to outside, but Outside can not ping into

inner network

• Don’t allow TCP traffic from outside going in, but going out and

others traffic is allowable

• Hosts in LAN2, LAN4 can telnet to Router3

• Hosts in LAN1, LAN3 can not telnet to Router3

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ACL Practise

• Don’t allow IP traffic from LAN1 to LAN2, and LAN1 to LAN3

• Deny all TCP traffic from LAN1 to other network except WEB access, allow all

others.

• Allow FTP traffic from LAN2 to LAN3

• Don’t allow IP traffic from LAN2 to LAN3

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Standard ACL Placement

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Extended ACL Placement

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COMPLEX ACLs

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Types of Complex ACLs

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Dynamic ACLs

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Dynamic ACLs

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Dynamic ACLs

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Reflexive ACLs

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Reflexive ACLs

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Time-based ACLs

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Time-based ACLs

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Time-based ACLs

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Troubleshooting Common ACL Errors

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Summary

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Tiêu đề	Chapter 5 - ACLs
Trường học	Học viện mạng Bach Khoa
Chuyên ngành	Networking
Thể loại	lecture notes

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