1 實驗九：建置網路安全閘道器 教師： 助教：

2 Outline  Background  Proxy – Squid  Firewall – IPTables  VPN – OpenVPN  Experiment  Internet gateway  Firewall  VPN network

3 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

4 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  Tunneling  Encryption & Decryption  Key management  IPSec

5 Proxy – Squid  The most popular open-source proxy server  Support  ICP (Internet Control Protocol)  Transparent Proxy

6 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

7 VPN – OpenVPN  A famous VPN software of Linux  Support IPSec technique  Support to separate multiple tunnels  Client-Server based Through VPN software

8 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

9 Experiment – Firewall  Prevent hackers’ attacks  Use IPTable’s rules to filter the attack packets  Deny the ping packets from outside  Environment setup

10 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