NAT-PAT-DHCP

ผศ.ดร. อนั�นัต์ ผลเพิ่ �มAsst.Prof.Anan Phonphoem, Ph.D.

anan@cpe.ku.ac.thhttp://www.cpe.ku.ac.th/~anan

Computer Engineering DepartmentKasetsart University, Bangkok, Thailand

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Network Address Translation IP depletion Problem ? Conserve IP addresses Enable networks to use private IP

addresses on internal networks Security ?

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Private IP address

Class

RFC 1918 CIDR prefix

A 10.0.0.0 – 10.255.255.255

10.0.0.0/8

B 172.16.0.0 – 172.16.255.255

172.16.0.0/12

C 192.168.0.0 – 192.168.255.255

192.168.0.0/16

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NAT Operates at the border of a stub

network

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NAT

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Configure NAT Static Translation Dynamic Translation

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Static Translation

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Dynamic Translation

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PAT (Overloaded NAT)

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PAT

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NAT command

debug ip nat

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Disadvantages of NAT Delay Loss of end-to-end ability Might not work with some

applications

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Dynamic Host Configuration Protocol (DHCP)

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DHCP Message

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Configure DHCPGW

Reserved Static IP (e.g. for servers)

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Verifying DHCP

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DHCP Relay

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DHCP Relay