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LIS Discovery using IP address and Reverse DNS
draft-thomson-geopriv-res-gw-lis-discovery-03
Ray Bellis, Advanced Projects, Nominet UK
IETF 77, GeoPriv WG
Anaheim, 23rd March 2010
History
draft-ietf-geopriv-lis-discovery
• Uses a domain name to find a (U-)NAPTR record
– Domain name obtained via DHCP
• Previously also took the PTR record for the host and
mangled that host name to find the domain name
• DNS folks (myself included) didn’t like this:
– The LIS is part of the local network architecture
– But hostnames very often have no relationship to the
network architecture
Problem Statement
• DHCP option rollout will take years, particularly in
residential environments
• What’s your domain name, if PTR records are
unsuitable?
Proposed Solution
• Don’t invent a domain name – there’s already a domain
with a 1:1 mapping between IP and name:
– in-addr.arpa
– ip6.arpa
• The reverse DNS tree has a very strong association with
the underlying network architecture
• Find your public IP (using STUN)
• Put the U-NAPTR record directly in the reverse DNS tree
Example
• STUN says my public IP is 198.51.100.5
• Do a lookup for the /32 host address
– 5.100.51.198.in-addr.arpa. IN NAPTR?
• If lookup fails, try at the /24 boundary:
– 100.51.198.in-addr.arpa. IN NAPTR?
• If lookup fails, try at the /16 boundary
– 51.198.in-addr.arpa. IN NAPTR?
• If lookup fails, give up
• else pass the resulting NAPTR record to the normal LIS
Discovery algorithm
(Similar process documented for IPv6 addresses)
Next Steps
• Working Group adoption?