Re: [fw-wiz] Firewalls acting as access controllers

From: Kevin (kkadow_at_gmail.com)
Date: 05/26/05

  • Next message: Chris Buechler: "Re: [fw-wiz] Firewalls acting as access controllers"
    To: firewall-wizards@honor.icsalabs.com
    Date: Wed, 25 May 2005 19:11:19 -0500
    
    

    On 5/25/05, Green Horn <teachgreenhorn@yahoo.com> wrote:
    > Hi,
    > I am new to firewalls.
    > Do firewalls provide dynamically defined access
    > control i.e., can they act as access controllers.

    In general, firewalls can be configured to enforce
    authentication to the firewall before users are
    permitted to access select services. Often the
    policy can be defined so that once the user has
    authenticated to any one service, the firewall
    will permit that source IP address to access to
    multiple services/ports (similar to "authpf"), for
    a limited duration. This feature is often labeled
    as "Single Sign On".

    There is exposure by in just opening up TCP/IP
    access to multiple ports/protocols for all requests
    from a given source IP address based on a remote
    user authenticating once for just one service.

    The common alternative to mitigate this risk is to
    instead use a VPN or "SSL VPN".

    > e.g., it should be able to do the following, a user
    > tries to access a resource, the packets would come to
    > the firewall, if they are HTTP packets and the user is
    > new (from IP address not being in the authenticated
    > list), the packets would be redirected to a webproxy,
    > the webproxy tries to get the user authenticated by a
    > AAA server (say RADIUS), the firewall would get an
    > authorization message from the AAA server (or
    > webproxy), saying the time the user must be allowed
    > access, the resources he can access etc.
    > The firewall would provide that access.

    Yes, except usually the firewall does MITM on the
    protocol for the authentication prompt and processing,
    assuming a protocol like HTTP, FTP, Telnet where a
    password prompt can be presented to the user for a
    response. Pretty slick.

    The firewall then checks the username and password
    against an internal account table, against RADIUS,
    LDAP, or another authentication service, checking only
    for a basic Pass/Fail response.

    While it's possible that a firewall might actually pass
    details about the resource being requested to a AAA
    server and ask for not only Authentication of the user
    credentials but also Authorization for that specific
    resource, this is rare. Usually controls (what resources
    authenticated IPs can access for how long) are just set
    internally in the firewall's own user/group database.

    Kevin Kadow
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  • Next message: Chris Buechler: "Re: [fw-wiz] Firewalls acting as access controllers"

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