WEB FILTERING

Internet Censorship

Omid Abbasi (Student at Shiraz University)

1/21

Our Goals

• What is the censorship?

• When it started?

• Why ?

• Who started?

• What is the scope of censorship?

• Who censor the internet?

• How does the censorship take place?

• Where is the censorship happening?

• How to get ride of it?

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What is internet censorship?

• Internet censorship is essentially a method used by corporations, governments and others in order to filter what a user can view on the internet.

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Why Started?

4/21

Critics

• Families:• limit what sites their children can access.

• Governments:• Viewing political pages that are against the ruling party.

• News pages that would inform citizens of conflicts.

• Pages they would deem obscene.

5/21

Solution

• Shutdown the internet• Control publishers• Control Access

6/21

What Countries censors?

Not Free Partially Free

Free No Data7/21

Censor What?Traditional social values

Political National security

8/21

What Iran censors

9/21

Types of censorship

What is facebook.com

facebook.com is 173.252.110.20

Hello are you there?

VPS

Give me facebook.com homepage

Normal web browsing

Censorship node

10/21

DNS hijacking

What is facebook.com

10.10.34.34

Hello are you there?

VPS

Censorship node

Types of censorship (cont’d)

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Address or Port blocking

Hello are you there?

Censorship node

What is facebook.com

facebook.com is 173.252.110.20

Types of censorship (cont’d)

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Web content filtering

Hello are you there?

Censorship node

What is facebook.com

facebook.com is 173.252.110.20

Hello are you there?

Types of censorship (cont’d)

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Where Internet filtering accrues(Iran)?

14/21

When there is a problem there is a solution

15/21

Primary objective

Connect censored users to the uncensored Internet

securely and anonymously.

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Anatomy of Anti-Censorship System

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Anti censorship methods

http proxy

18/21

CGI proxy

phproxy

James Marshall

Anti censorship methods (cont’d)

19/21

IP tunneling (VPN)

In IP tunneling, every IP packet, including addressing information of its source and destination IP networks, is encapsulated within another packet format native

to the transit network.

Anti censorship methods (cont’d)

20/21

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