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

14 July 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

14 July 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 ????

14 July 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

14 July 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

14 July A normal web transaction User IP: Security……How Do I Care???

14 July Transaction through a proxy User IP: proxy.inst.edu IP: More secure…. Add firewall…packet filter; block access to sites

14 July Caching –Proxy (Cache MISS!!) proxy.inst.edu IP: Cache MISS User IP:

14 July Caching –Proxy ( cache HIT) User IP: proxy.inst.edu IP: Cache HIT Improves speed of surfing

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

14 July 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

14 July Default Gateway ???  Like routers…

14 July 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 July 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

14 July 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

14 July 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

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

14 July  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

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

14 July Configuring Internet Explorer

14 July Click Start, Programs, Internet Explorer

22 Click Tools, Internet Options

14 July Click Connections

14 July 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)

14 July Click LAN Settings LAN connections ONLY

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

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

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

14 July 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….

14 July

14 July