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Schaller: The long journey towards good free video conferencingSchaller: The long journey towards good free video conferencingPosted Oct 15, 2012 20:57 UTC (Mon) by dlang (✭ supporter ✭, #313)In reply to: Schaller: The long journey towards good free video conferencing by raven667 Parent article: Schaller: The long journey towards good free video conferencing
except that none of these systems are really local-only services.
If nothing else, I'll bet that every single one of them is going to want to do NTP lookups to set their clock. That will require hitting the Internet.
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Schaller: The long journey towards good free video conferencing Posted Oct 15, 2012 21:49 UTC (Mon) by martinfick (subscriber, #4455) [Link]
True! It would be nice if all these nifty too powerfull, bufferbloat producing, home gateway routers could server ntp by default to internal networks. And that if only there were a default protocol (perhaps DHCP?) that would point these device to our internal NTP gateway, and if only our new devices would do this by default for us if the gateway advertises this, instead of always relying on an outbound connection! Anyone device vendors working on standardising this one yet?
Schaller: The long journey towards good free video conferencing Posted Oct 15, 2012 21:57 UTC (Mon) by dlang (✭ supporter ✭, #313) [Link]
If you use DHCP to allocate IPv6 addresses, this is possible, but the link-local addresses are defined as being created independantly of any DHCP server.
and once you get an IP address from the DHCP server, you now have a real IPv6 address that is accessible from anywhere on the Internet (unless you have a firewall or NAT device in place)
Schaller: The long journey towards good free video conferencing Posted Oct 16, 2012 2:35 UTC (Tue) by elanthis (guest, #6227) [Link]
Link local addresses can still use service discovery on the local network to find things like an NTP server. Link local addresses basically depend on service discovery to even be useful.
Also, a DHCP server does not guarantee a binary option between public Internet connectivity or the use of a firewall/NAT. There's nothing in the world that says a DHCP server can't assign local addresses (fc00::/7) that don't route over the 'Net. You'd need a truly bad ISP for attackers to even be able to send you packets to those addresses, or receive packets from those addresses.
Schaller: The long journey towards good free video conferencing Posted Oct 16, 2012 2:36 UTC (Tue) by kevinm (guest, #69913) [Link]
There is already a DHCP option defined for specifying NTP server addresses, and NTP also supports broadcasting a query on the local subnet. It would make sense for home routers to listen on the local subnet for NTP broadcast requests and reply to them.
Schaller: The long journey towards good free video conferencing Posted Oct 15, 2012 22:01 UTC (Mon) by raven667 (subscriber, #5198) [Link]
I understand that there is a reason these devices are being connected to the Internet so a truly local-only device is probably rare. One added point though is that the device could use is public address for client connections (NTP, download updates, DNS, etc.) and advertise its fe80:: address for management and local-only services using multicast-DNS as is standard now-a-days. That's very simple to implement and greatly reduces the attack surface for services that shouldn't be remotely accessible.
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