On Fri, Jul 15, 2011 at 1:23 PM, prasanth kp <[email protected]> wrote: > i am a begginer in linux,so i have so many doubts in linux.so i will share > my doubts with u >
Sure :-) > 1.what is squid?(and its use) > Squid is a Proxy Server to start with for a beginner a beginner. So Squid will sit most probably on your firewall. When users in the LAN access http, https, ftp and such protocols the proxy intersects it and the proxy connects to the servers on the internet and fetched the data for them Squid can also cache the files so when the next user asks for the same file it can server the user from the cache and not fetch it again from the internet. Squid can also act as a reverse proxy. A reverse web proxy sits in front of web servers and caches the contents of the web server and gives it to users accessing the web server. Squid is actually called Squid-Cache http://www.squid-cache.org/ Apache can also act as a reverse proxy http://www.apachetutor.org/admin/reverseproxies Also there are other proxy/caches too like https://www.varnish-cache.org/ http://haproxy.1wt.eu/ http://haproxy.1wt.eu/#othe to mention a few. > 2.what is ip table?(and its use) > IP tables is the firewall that comes with the Linux kernel. Most other firewalls in Linux are a front end to iptables. Firewalls are some times called packet filters too. A few examples are. http://www.openbsd.org/faq/pf/ http://mail-index.netbsd.org/netbsd-announce/2010/09/13/msg000110.html http://en.wikipedia.org/wiki/IPFilter The popular easy to configure Firewall suite pfSense is based on OpenBSD's PF. http://www.pfsense.org/ > 3.what is dansguardien?(and its use) > Dansguardian is a content filter. Let us say you use PF/NPF/IPF/IPTables as a firewall you can only filter using IPs, Port Nos, protocols etc. If you wanted to filter using URLs like you want to block all URLs ending with .exe or .mp3 you should you some thing like Squid which filters stuffs on a higer level. But if you want to block web pages with some particular content the you should use a content filter like dansguardian which filters on an even more higher level. Now if you want to know what the different levels are then read http://compnetworking.about.com/cs/designosimodel/a/osimodel.htm http://en.wikipedia.org/wiki/OSI_model > 4.What is transparent proxy?(and its use) > Well when you configure a proxy like squid you should make the users enter the proxy information in their browser either manually or automatically. In a transparent proxy the client side needs no configuration. the proxy transparently does its job. > i have a linux firewall in my office(Zentyal).Here i am using transparent > proxy.i don't know what is this.My problem is ...i can block all http > sites,but can't block https site.This is the major issues existing in my > company.so pls help me > never used zentyal, but it you can do it with http then you should be able to do it with https and ftp at least in any decent firewall :-) hope this helps --Siju _______________________________________________ Indian Libre User Group Cochin Mailing List http://www.ilug-cochin.org/mailing-list/ http://mail.ilug-cochin.org/mailman/listinfo/mailinglist_ilug-cochin.org #[email protected]
