RE: [fw-wiz] Sources for Extranet Designs?

From: Steven A. Fletcher (sfletcher_at_bcsc.com)
Date: 02/23/04

  • Next message: Wes Noonan: "RE: [fw-wiz] Sources for Extranet Designs?"
    To: "Firewall-Wizards" <firewall-wizards@honor.icsalabs.com>
    Date: Mon, 23 Feb 2004 14:43:22 -0600
    
    

    My opinion on that would that it's up to the clients to protect
    themselves. Recently, I set up a connection for a law enforcement
    customer who would be accessing a county database and a state wide
    database through this connection. Other county departments would also
    be accessing this same network. Since I was already putting in a
    firewall as a requirement for this connection, I included a third NIC so
    that the internal network would be protected from this other network
    also.

    My theory is that if I can't control anything on that network, then I'm
    not going to trust it. This applies to the Internet, so why should it
    not apply to other unfamiliar, untrusted networks? I would spell this
    out in the partner agreement to alleviate any liability.

    Steve Fletcher
    Senior Network Engineer, MCSE, Master ASE, CCNA
    BCSC Technology Solutions
    Phone: (309)664-8129
    Toll Free: (888) 764-8100 ext. 129
    Fax: (309) 662-6421
    sfletcher@bcsc.com

    -----Original Message-----
    From: firewall-wizards-admin@honor.icsalabs.com
    [mailto:firewall-wizards-admin@honor.icsalabs.com] On Behalf Of Bob
    Alberti
    Sent: Monday, February 23, 2004 2:09 PM
    To: Firewall-Wizards
    Subject: RE: [fw-wiz] Sources for Extranet Designs?

    One thing I always wonder about in Extranet designs: how liable are you
    (the host of the Extranet) if two of your Extranet customers are
    competitors? If Customer A can hack your Extranet to, for instance,
    inspect
    Customer B's orders, or even to hack Customer B's network, how liable
    are
    you for not providing a more secure Extranet environment?

    Its one thing to protect the host organization from Extranet clients:
    its
    another entirely to protect clients from each other.

    -----Original Message-----
    From: firewall-wizards-admin@honor.icsalabs.com
    [mailto:firewall-wizards-admin@honor.icsalabs.com]On Behalf Of Wes
    Noonan
    Sent: Monday, February 23, 2004 1:31 PM
    To: 'Baumann, Sean C.'; 'R. DuFresne'
    Cc: 'Paul Robertson'; firewall-wizards@honor.icsalabs.com
    Subject: RE: [fw-wiz] Sources for Extranet Designs?

    > 1.) If you say you should never allow access to resources on your
    > protected or internal network, how do you handle giving access to
    > services that reside on machines that cannot be duplicated (i.e.
    > expensive mainframes)?

    There are a couple of approaches that I can think of off hand. Approach
    1 is
    to design the services with extranet connections in mind. Simply put,
    maybe
    the mainframe isn't the right place to house that resource. This is
    probably
    not the answer that you want to hear though. Approach 2 is to accept
    that
    you have a business limitation that is going to force you to implement a
    less than ideal security solution. At that point, you mitigate it. What
    precise ports need to be opened from the extranet to the internal
    resource
    and grant *only* that access. If they need SQL access but not NFS access
    then make sure that your firewall only permits SQL traffic to pass
    between
    the two networks. Things like that.

    > 2.) Do most companies require routable address on their extranet?
    > Currently we use RFC1918 address for our extranet, but we see that
    this
    > will become a problem in the future as we add partners.

    Depends. Assuming that you are going to be using firewalls and
    advertising
    your internal resources as something else (through the use of NAT, etc.)
    then you can do that and make the routable addresses what the extranet
    partners think they are going to connect with. That being said, you can
    pretty much pick any RFC1918 address space at that point and use it in a
    similar fashion. The obvious alternative is that someone will need to
    change
    their address space.

    More detailed design you will probably have to pay me for. :-)

    One thing that this scenario really graphically depicts is why
    separation of
    resources is such a valuable objective. Sure, it sounds really nice to
    have
    all your stuff running on a mainframe running Linux hosts but these are
    the
    kinds of security problems you will then run into. (feel free to expand
    this
    statement as you see fit - i.e. integrated firewall/ids/content
    filter/spam
    control/virus scanning or separate switches vs. VLANs).

    HTH

    Wes Noonan
    mailinglists@wjnconsulting.com
    http://www.wjnconsulting.com
    Hardening Network Infrastructure - A concise how to guide
    Available Spring 2004
    Order at http://tinyurl.com/2nof4

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