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實驗九：建置網路安全閘道器

教師：助教：

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Outline

Background Proxy – Squid Firewall – IPTables VPN – OpenVPN Experiment

Internet gatewayFirewallVPN network

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Background (1/2)

Proxy Acts as a gateway between a local area network and the Internet Transparent Proxy

Clients forced to pass through proxy for monitoring purpose Security control

ACL (Access-Control-List) A list of permissions attached to a URL or a website

ICP (Internet Control Protocol ) Tracks the internet address of nodes, routes outgoing messages, and recognizes incoming messages

Firewall Use static policies to filter specific traffic types Filter parameters consist of

Source and target address Ports Direction Protocols

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Background (2/2)

VPN A VPN can send data across secured and encrypted private channels

between two points over a public network. Used to provide secure communication

TunnelingEncryption & DecryptionKey management IPSec

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Proxy – Squid

The most popular open-source proxy server Support

ICP (Internet Control Protocol) Transparent Proxy

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Firewall – IPTables

Rule-based packet filter Three types chain of rules

Input chain – Input packet rule control chain Output chain – Output packet rule control chain Forwarding chain – IP masquerade packet rule control chain

Three types chain of rules on NAT table Prerouting chain – Rule control chain before routing packets Postrouting chain – Rule control chain after routing packets Output chain – Rule control chain for output packets

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VPN – OpenVPN

A famous VPN software of Linux Support IPSec technique Support to separate multiple tunnels Client-Server based

Through VPN software

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Experiment – Internet gateway

Configure security gateway to manage traffic Add three rules

Adult websites Denial of a part of a computer’s connections Denial of downloading

Environment setup

Our Linux gateway

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Experiment – Firewall

Prevent hackers’ attacks Use IPTable’s rules to filter the attack packets Deny the ping packets from outside

Environment setup

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Experiment – VPN Network

Connect two networks using VPN Install the VPN software on two linux servers Configure the tunnel parameters Build security connections between LANs

Environment setup