I have an established windows network of around 80 machines.
I want to reimplement the network using a centralized firewall and file server on one Redhat enterprise linux machine. The entire network except a couple of systems function on windows. Please suggest me the configuration required for this server and also advise me in steps, the software to be installed and configured for implementing this system.
Thanks in advance

Its a rather involved process, luckily if you are going the RHEL route, you will have tech support people to phone and they will probably install it to your exacting specifications.

Should you be using the "Idea" of RHEL, but not wanting to pay for it, then may I recommend CentOS, which is binary compatible, but without the logos..

How to enable the CentOS firewall. (looks a lot like the RHEL firewall.. lmao)
http://mirror.centos.org/centos/4/do...allconfig.html

Excellent Samba HOWTO's, show you how to setup your server to serve files.
http://us4.samba.org/samba/docs/man/...TO-Collection/

So, to install and configure this the easiest,

I would read something like this: http://www.howtoforge.com/perfect_setup_fedora_core_5

Then download CentOs: http://mirror.centos.org/centos/5/isos/

Then, during the install, when it asks you what roles you want, select:

FileServer

And thats it.

Then, when it asks you if you want to enable the firewall, enable it!

You will have to configure routing and rules yourself, because that is very network dependant, some sites require inbound VPN's, others need to serve HTTP from a DMZ etc.. its best to tailor that yourself. There are tools online to create the configs for you, this site explains iptables rather well:
http://www.howtoforge.com/linux_iptables_sarge (just read the Red Hat stuff..)

Its a start..

In addition to the excellent reply above, I would just like to give extra emphasis to a few points:

• Always keep in mind the basic principle of what you are trying to do with a firewall. Block everything, unless it is necessary for what you/your users need.
  
• In a situation like this, it would be useful to do some testing to ensure that the firewall is doing what you want it to. You need to think about how you are going to do that.
  
• In general, linux firewalls are netfilter/iptables based. There are various things which are touted as firewalls which are really 'easy to use front ends to iptables'. It is good to understand iptables and have a look at the rules that you have in place to see whether there are any surprises there. If you are stuck you may want to look at http://iptables-tutorial.frozentux.n...-tutorial.html
  but that might just be the wrong place to start, for you.
  
• In a situation like this, I would consider using Squid (web caching). It probably (slightly) boosts performance, it reduces bandwidth usage, it offers the possibility of controlling and doing some simple monitoring of acesses (blocking websites, listing accessed websites, time-based access controls...).
  
• I would also consider caching name look-ups, for performance reasons. Bind is the obvious app for this (although it may be more than is necessary, depending on the complexity of the system).

Given those comments (and given that this is in the Newbie forum) your first stop should be a plan. How are you going to develop/introduce this stuff without causing unacceptable service disruption?