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CONFIGURING A PROXY SERVER IN LINUX. BY ROHIT KAUL CS , BITS-PILANI. 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
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CONFIGURING A PROXY SERVER IN LINUX BY ROHIT KAUL CS , BITS-PILANI
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
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 ????
What is a Proxy Server ?? • Intermediary server between clients and the 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
Uses of Proxy-Server • Enhancing Security not individual security concerns, saves resources, money etc • Caching faster web surfing • Firewall • Filtering Contents
www.jstor.org User IP: 1.2.3.4 A normal web transaction Security……How Do I Care???
proxy.inst.edu IP: 2.3.4.5 www.jstor.org User IP: 1.2.3.4 Transaction through a proxy More secure…. Add firewall…packet filter; block access to sites
proxy.inst.edu IP: 2.3.4.5 www.jstor.org User IP: 1.2.3.4 Caching –Proxy (Cache MISS!!) Cache MISS
proxy.inst.edu IP: 2.3.4.5 www.jstor.org User IP: 1.2.3.4 Caching –Proxy ( cache HIT) Cache HIT Improves speed of surfing
Proxy In Linux… • Installation • Connecting Linux PC to LAN • Configuring proxy module/application • Configuring prospective clients’ browsers • INSTALLATION easy!!!
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
Default Gateway ??? • Like routers…
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
Configuring SQUID • Squid???? • it is a proxy – caching server which runs on *nix based platforms. Why Squid? apart from others.. • Available free of cost , open-source • Features content-filtering and password authentication for users using external programs
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 clean • Similar to WINZIP
Squid.conf file • Open in any standard editorvi/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
Restricting Internet Access • ACLs ( access control Lists ) • Acl acl_nameacl_typedata • 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
Starting squid squid start /etc/init.d squid start / restart • Stopping squid Squid stop /etc/init.d squid stop
Dummy interface?? • What is dummy interface??? • eth0 eth1 • eth0 eth0:0 • Interface at startup • .bashrc file
Select Your Connection For LAN connection (within RRL) For Dial-UP Connection (from Home)
LAN connections ONLY Click LAN Settings
Select Use a proxy server for this connection.In Address box, type 10.10.7.245 & in Port box 8080Select Bypass proxy server for local addresses
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
Click OK. • Click OK. • Click OK. Similarly one can configure graphical browsers like MOZILLA or OPERA
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….