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Re: [Captive-portals] API / ICMP for status and remaining time

Ideally, the "Policy Class" hint could be used instead of putting the URL in the ICMP packet (which was our original thought). I think it helps to require RFC 7710 to get the base CP URL so that Capport ICMP is meaningless in networks not configured with Capport DHCP. 

On Tue, Sep 6, 2016 at 12:46 PM, Michael Richardson <[email protected]> wrote:

Dave Dolson <[email protected]> wrote:
    > An ICMP extension could notify a sender that a 5-tuple connection is walled
    > off‎. It works for all IP protocols (TCP, UDP, GRE, even ICMP-echo).
    > ‎This will be more real-time than relying on the sender to periodically probe
    > well-known servers on port 80.

Agreed, it's good.  Like all ICMPs, we must assume that they could be forged.

    > Such a message should indicate a reason, which could be a URL to a JSON/REST
    > interface.
    > Or, it could simply be an event that means "go probe port 80 to get
    > redirected"

While I think it's slight less attackable to get redirected; I also favour
putting the URL in the packet, even if we ultimately can not trust it.

Michael Richardson <[email protected]>, Sandelman Software Works
 -= IPv6 IoT consulting =-