1. 14 July 2004 1 CONFIGURING A PROXY SERVER IN LINUX BY ROHIT KAUL CS, BITS-PILANI

2. 14 July 20042 PRESENTATION LAYOUT  Brief introduction to LINUX  What is a proxy???  Its Uses and Need???  Security aspects and Web Caching  Connecting a PC to LAN  Introduction and Configuration of Squid  Configuration of clients’ Browser  Conclusions

3. 14 July 20043 Introduction to Linux  Linux – a phenomenon?  Linux has provided a common platform for the Free software that was being created all over the world….  Linus Torvalds, 1991, University of Helsinki  GPL (General Public License)  Distributions in market Red Hat, Debian etc  WHY LINUX ????

4. 14 July 20044 What is a Proxy Server ??  Intermediary server between clients and the actual server actual server  Proxy processes request  Proxy processes response  Receives the client request  Decides if request will go on to the server  May have cache & may respond from cache  Acts as the client with respect to the server  Uses one of it’s own IP addresses to get page from server

5. 14 July 20045 Uses of Proxy-Server  Enhancing Security not individual security concerns, saves resources, money etc not individual security concerns, saves resources, money etc  Caching faster web surfing faster web surfing  Firewall  Filtering Contents

6. 14 July 20046 A normal web transaction User IP: 1.2.3.4 www.jstor.org Security……How Do I Care???

7. 14 July 20047 Transaction through a proxy www.jstor.org User IP: 1.2.3.4 proxy.inst.edu IP: 2.3.4.5 More secure…. Add firewall…packet filter; block access to sites

8. 14 July 20048 Caching –Proxy (Cache MISS!!) proxy.inst.edu IP: 2.3.4.5 Cache MISS User IP: 1.2.3.4 www.jstor.org

9. 14 July 20049 Caching –Proxy ( cache HIT) User IP: 1.2.3.4 proxy.inst.edu IP: 2.3.4.5 www.jstor.org Cache HIT Improves speed of surfing

10. 14 July 200410 Proxy In Linux…  Installation  Connecting Linux PC to LAN  Configuring proxy module/application  Configuring prospective clients’ browsers  INSTALLATION easy!!! easy!!!

11. 14 July 200411 Connecting Linux PC to LAN  Red Hat menu, System Settings  Network  ( or type “neat” as root )  Network configuration window appears  Devices tab  eth0 interface ( double-click)  A pop-up window appears asking for:  DHCP / Static Addressing  Choose Static….and fill in IP Address, Netmask, Default Gateway Address. click OK, close the window and click ACTIVATE

12. 14 July 200412 Default Gateway ???  Like routers…

13. 14 July 200413 Configuring DNS information  DNS ???  Click DNS tab in network configuration window..  Enter primary and secondary DNS nameservers ….in case local DNS is configured enter the address as primary DNS  Click APPLY button at the bottom  Click CLOSE, and ACTIVATE

14. 14 July 200414 Configuring SQUID  Squid????  it is a proxy – caching server which runs on *nix based platforms. *nix based platforms. Why Squid? apart from others.. 1.Available free of cost, open-source 2.Features content-filtering and password authentication for users using external programs

15. 14 July 200415 Installation of squid  From RPM packages…  Use Package Manager and install from CD  From Source  Unzip in some temporary directory  Move to it…and run./config  Run make make install make install make clean make clean  Similar to WINZIP

16. 14 July 200416 Squid.conf file  Open in any standard editor vi/vim emacs  Lots of options, anybody with basic knowledge of proxy and networking can configure it.  http port default 3128  Cache_mem default 8MB  Cache_dir directory subdirectory subsub directories /var/squid/cache

17. 14 July 200417 Restricting Internet Access  ACLs ( access control Lists )  Acl acl_name acl_type data  Acl node scr 10.10.7.239  Acl node2 scr 10.10.7.72  Acl lunchtime time M 13:00-14:00  http_access deny node lunctime  http_access deny node

18. 14 July 200418  Starting squid squid start /etc/init.d squid start / restart squid start /etc/init.d squid start / restart  Stopping squid Squid stop /etc/init.d squid stop

19. 14 July 200419 Dummy interface??  What is dummy interface???  eth0 eth1  eth0 eth0:0  Interface at startup .bashrc file

20. 14 July 200420 Configuring Internet Explorer

21. 14 July 2004 21 Click Start, Programs, Internet Explorer

22. 22 Click Tools, Internet Options

23. 14 July 200423 Click Connections

24. 14 July 200424 Select Your Connection For LAN connection (within RRL) For LAN connection (within RRL) For Dial-UP Connection (from Home) For Dial-UP Connection (from Home)

25. 14 July 200425 Click LAN Settings LAN connections ONLY

26. 14 July 200426 Select Use a proxy server for this connection. In Address box, type 10.10.7.245 & in Port box 8080 Select Bypass proxy server for local addresses

27. 14 July 200427 Select Use the same proxy server for all protocols. Type *.ou.ac.lk; 192.248.73.* in Do not use proxy server for addresses beginning with box

28. 14 July 200428  Click OK. Similarly one can configure graphical browsers like MOZILLA or OPERA

29. 14 July 200429 Conclusions  In an era where even a single click of mouse is potent enough to cause a full fledged attack, installing proxies and other security modules is no more a luxury that every system administrator enjoys…  Its a necessity….

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