Re: Wi-Fi User Authentication

From: Tiago Filipe Dias (tiago.dias_at_tp.telepac.pt)
Date: 07/21/03

  • Next message: David Gillett: "RE: Microsot Liability for vulnerabilities"
    Date: Mon, 21 Jul 2003 17:17:14 +0100
    To: security-basics@securityfocus.com
    
    

    Why simply not use FreeRADIUS or even inspite expensive, radiator ?

    One of the solutions could be radius configurated communicating with a ldap.

    sincero

    On Sun, 20 Jul 2003 13:29:32 -0400
    N407ER <n407er@myrealbox.com> wrote:

    > Hi, folks,
    >
    > We're (I use the anonymous "we" here with apologies) in the process of
    > setting up a Wi-Fi access point here. Bear in mind that we have little
    > control over client configuration or consistency--personal computers
    > would be used, with any OS--and don't want to spend a lot of time
    > providing technical support.
    >
    > One of the other groups here went with a product called ReefEdge to
    > provide Wi-Fi authentication to prevent unauthorized usage; as far as I
    > can tell from chatting with them, it does pretty much the same as what
    > we were thinking; however, due to cost, we'd prefer to develop something
    > in-house or use something open source.
    >
    > So the plan I had was this:
    >
    > Set up the gateway with a firewall which would by default redirect all
    > outgoing tcp/80 traffic to some the local machine, which would have a
    > "sign-in" page. Users authenticate with their username/password, and a
    > ruleset is temporarily added to the firewall allowing them full outgoing
    > traffic. When they are done, they log out, deleting the ruleset (or we
    > time out their connection after a certain amount of inactivity).
    >
    > The real question I have is, even if we were to use MAC address matching
    > instead of IP (iptables has an option in the 2.4 kernel for MAC
    > matching, as I recall) anyone can grab all the information he needs to
    > spoof a valid connection from a single captured packet. Now, assuming we
    > close or timeout connections when the user logs out, he'd have to take
    > over a connection still in use. There is no guarantee, though, that the
    > victim client would even notice (nor would we), especially if it is
    > running something like ZoneAlarm and simply drops, with no ICMP reject,
    > all unexpected packets. This would mean the attacker could simply pick
    > up all the responses to his spoofed connections without the victim
    > noticing.
    >
    > So how can you prevent this without using something which would require
    > client-side support, like VPN? VPN is not much of an option for us, I've
    > been told that a Mac VPN client costs money, and regardless, we don't
    > want to have to support user configuration. Do I have to simply hope no
    > one will be able to hijack a connection which is in use?
    >
    > I've seen software which claims to detect attempts to hijack Wi-Fi
    > networks, but most appear to just detect brute-forcing on the IP
    > address, etc. Any attacker could merely passively capture a single
    > packet and bypass this detection in a snap.
    >
    > Thanks for any help.
    >
    >
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