RE: Securing a Local Network

["Halverson, Chris" <chris.halverson () encana com>]

1. Show the Management of your company the insecurity of the Peer to Peer
setup and discuss what risks are they willing to accept.  
        Ex. Computer with the financial data's hard drive crashes, discuss
length of time that it would take to get that data back up and running.  
        Ex.2 Virus with payload enters network and causes all the machines
to crash and productivity is lost for the day.  What do all these things
mean to them???

2. Plan, plan, plan.  Design three alternate solutions for them a bronze,
silver, and Gold solution.  All with price tag's associated to them.    
        2a. Make the bronze least expensive solution, with only a few
components per year,
                the silver the preferred method for yourself to administer,
                and the gold the Cadillac of setups, planning for enormous
growth from the company (50 + users in 2 years)
All of these should contain an outline of what the pros, cons, and potential
risks associated to them.
        
Things to consider in the plans:
-Make sure that centralized server managed AV solution and if possible a
gateway AV solution as well.  This should be at the top of the list for the
infrastructure upgrade.  
-Look to securing the perimeter, test the reliability of the Firewall with
some scanning software and looking through the vulnerabilities list for your
specific product.  If this is a little Linksys Packet Filtering Firewall
look maybe to a Linux FW (ex. IPCOP, smoothwall or netfilter)
-Plan your Authentication factors.  Windows Active Directory, Samba/SMB
Linux Folder permissions, or keep the peer to peer (highly not recommended)
-Internal Training for the users 
-Time for setup
-Support for the products that you may purchase.
-Cost of getting the web server and the mail server internally versus having
it hosted externally.
-Make sure anything that is accessible from the internet should not be
internal to the rest of your network.
-Always account for your time for everything...
-Plan for future growth, and upgrade time frames (don't expect to have all
the things done in the next month, have a two to three year plan)
-Ensure milestones and expected time of completion.
-Include restore times for any possible failure or incident

Personal Recommendation:
For your situation I would look at MS small business server 2003 (caveat :
this product only goes up to 50 user licenses)
        -Utilize the Domain Services and the Exchange features of this
product ONLY.  
        -Pick up Xeon or Opteron processor based machine with minimum 1 Gb
of ram and redundant disk storage.  (Use easily available parts or Name
Branded Products and have spare parts in case)
        -Have a nightly backup procedure using tape and/or digital backup
media and safe offsite storage of this backup medium.
-Get a Cisco 1721 series Router using the FW inspection module with two WICS
to have a DMZ for external based services.  Mail Front End, web server, and
IDS
-Use an older box for Intrusion Detection on the internal network as well.
-Documentation of every step that you took to install and setup this new
configuration
-good logging facilities.

There is a lot more you could do and I am sure you will hear numerous
solutions.  Take them with a grain of salt and make sure the solution will
be easy for you to manage...

--- to the remainder of security gurus on the list ---
I have been looking at a good way for windows clients to authenticate to a
directory such as Active Directory within Linux and I have yet to find
anything of value.  There is PAM but I find it is not as robust as AD :( 

Does anyone have some sort of solution for this?

------------------------------------------------------










-----Original Message-----
From: John Roberts 
Sent: Tuesday, April 13, 2004 11:17 AM
To: security-basics () securityfocus com
Subject: Securing a Local Network


I started working as a sys admin at a small company (about 15 people) and
they are starting to think it's time to upgrade their network.  Right now
it's just 20 computers, running a mix of xp and 2000 on a local network,
sharing files, with almost no anti virus and the only protection from the
outside world is the NAT that the routers perform.  

I've tried to get the to upgrade to a domain, add a file server for backup,
get some office wide virus protection and maybe even take our email in
house, but they've balked at the price to setup a legit windows domain.  The
main goals are access control on the local network and virus / worm
protection.  I'm suggesting a Windows domain controller to enforce access
control and then an centralized anti-virus product.  Is this enough, and are
there other (easier, cheaper, more effective ways) to make sure that only
the people who need to can access the financial records, the computer people
can access the all computers when they need to, and some user decides to
download a cute little program won't destroy the whole network with a virus.


Is a linux domain controller a solution, considering everything else in
house is windows?  Is an anti-virus solution at the gateway better than an
anti-virus solution on each desktop?  Basically, what's a good way to set up
a solid base of network security, which can then be expanded on?

John Roberts


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any course! All of our class sizes are guaranteed to be 10 students or less 
to facilitate one-on-one interaction with one of our expert instructors. 
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of an Ethical Hacker to better assess the security of your organization. 
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