RE: Securing a Local Network

[Meidinger Chris <chris.meidinger () badenit de>]

Hi John,

just want to touch on a couple of points:

a linux domain controller would certainly be a possibility, with a
combination of samba/openldap/krb5 you can even simulate ADS. The
implementation costs, however, will be much higher than the
license/implementation costs with a wintendo DC.  

There would be many reasons to put a server in there, you could run
file/patch/auth/anti-virus and more on one machine for that size network. 

As far as AV, I would suggest putting in client-side AV for now, and
planning to expand to a virus-gateway for smtp/http/ftp at some point in the
future. At the moment, I would guess that the risk of getting infected files
from disks is similar to the risk of getting infected stuff by downloading
it. 

Regarding 'a good way to set up a solid base of security' I would recommend
you think about defense in depth, and start with things that will have the
largest impact first. The largest impact will be your DC and AV, which you
have correctly identified. Are you able to audit the router configs
yourself? If not then, add firewall to the 'large impact' items. Otherwise,
you probably can lock your router down tight enough to allow you to wait
with a firewall. (Some people will disagree, but I think that your
priorities are definitely your domain and you anti-virus.) 

If you want to talk in more detail, feel free to email me back.

Cheers,

Chris Meidinger

> -----Original Message-----
> From: John Roberts [mailto:roberts () tridecap com] 
> Sent: Tuesday, April 13, 2004 7:17 PM
> 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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to facilitate one-on-one interaction with one of our expert instructors. 
Attend a course taught by an expert instructor with years of in-the-field 
pen testing experience in our state of the art hacking lab. Master the skills 
of an Ethical Hacker to better assess the security of your organization. 
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