The point about UDP was primarily that the key attribute is the ability to receive an unsolicited packet, not that it was better than ICMP. On Thu, 17 May 2018 at 17:10, Warren Kumari <war...@kumari.net> wrote:
> On Thu, May 17, 2018 at 10:00 AM Erik Kline <e...@google.com> wrote: > > On Thu, 17 May 2018 at 08:17, Michael Richardson <mcr+i...@sandelman.ca> > > wrote: > > > Erik Kline <e...@google.com> wrote: > > > > In the latter case especially, what becomes clear is that the UE > > needs > > > > to be able to receive an unsolicited packet. ICMP is a canonical > > > > example of receiving and processing an unsolicited packet. But > it > > > > could also be something like a UDP socket listening on a well > known > > > > port that receives a 1-byte datagram, which causes the UE to > enqueue > > > > (for rate-limiting purposes) a captive API query. > > > On POSIX systems, it's clearly a lot easier to open a UDP socket from an > > > unpriviledged application than to open an ICMP socket. > > > Is this a consideration for you? > > > > [3] NetworkMonitor already rate limits requests from > > applications > > > > to revalidate the network, and these would likely be no different > > (or > > > > pretty much the same). > > > Or would NetworkMonitor do this anyway, and it has all the priviledges > it > > > needs anyway? > > The fewer privilege escalation points the better, I suppose. From that > > perspective a UDP socket may be less concerning, but perhaps not by much. > > NetworkMonitor has the appropriate privileges to do the needful, > regardless. > I'll start off by admitting that this is a cheap shot, but: > https://access.redhat.com/security/vulnerabilities/3442151 > I'm uncomfortable with the "let's have all machines which might possibly > connect to a network with a captive portal have a daemon listening on a > well-known UDP port" idea. Yes, it is very similar to "let's have all > machines which might possibly connect to a network with a captive portal > have a thingie watching for special ICMP messages", but somehow it feels > very different. Yes, I understand the irony of building networks based on > what makes Warren uncomfortable, but... > W > > _______________________________________________ > > Captive-portals mailing list > > Captive-portals@ietf.org > > https://www.ietf.org/mailman/listinfo/captive-portals > -- > I don't think the execution is relevant when it was obviously a bad idea in > the first place. > This is like putting rabid weasels in your pants, and later expressing > regret at having chosen those particular rabid weasels and that pair of > pants. > ---maf
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