1. Use Cases for the Public Suffix List

Gervase Markham - IETF 89 dbound - London - 2014-03-06



2. PSL 101

http://www.publicsuffix.org/

 * List of suffixes, with wildcards and exceptions
 * Algorithm for interpreting list
 * (Recently) ICANN area and PRIVATE area
 * Given a domain name of a number of labels, calculate:
    1. suffix, and/or
    2. 'registered' domain (suffix + 1)



3. PSL Example

*.uk
*.sch.uk
!bl.uk
!british-library.uk
!mod.uk
!national-library-scotland.uk
!nic.uk
!parliament.uk
...
            


4. Uses 1: Browsers

It's all about the Same Origin Policy.

 * Cookies/LSOs
 * document.domain
 * URL bar and other UI things
 * Distinguishing searches from navigations (ignores PRIVATE)
 * Wildcard certificate acceptance (ignores PRIVATE)
 * Quotas, permissions and exceptions
 * Process separation
 * Shared Dictionary Compression for HTTP (SDCH)



5. Uses 2: Others

 * CAB Forum Baseline Requirements (avoid over-broad wildcards)
 * DMARC (anti-spam)
 * HTML5 (for document.domain definition)
 * ...
 
    Insert your use here:
    https://wiki.mozilla.org/Public_Suffix_List/Uses



6. So What's The Common Denominator?

 * Common ownership inside
 * Trust boundary at the edge



7. Operational Considerations

 * No blocking lookups
 * No DOS targets
 * No large datasets
 * Problems with making esoteric DNS requests



8. Any Questions?

https://wiki.mozilla.org/Public_Suffix_List/Uses