Mozilla Implements TLD Whitelist for Firefox in Response to IDN Homogr aphs Spoofing

Thu Jul 28 16:34:57 UTC 2005

Florian Weimer wrote:

>* Jason Sloderbeck:
>
>  
>
>>Yes, it's recognized by Mozilla and others as the job of the Internet
>>Architecture Board (in particular, the IAB-IDN group) to make a final
>>decision on how to deal with homographs.
>>    
>>
>
>Homographs are a classical example of a PR attack.  It's a complete
>non-issue.  In practice, people don't use domain names to assess the
>credibility of web sites.  1/l/I and 0/O are homographs as well, and
>the Internet hasn't collapsed as a result.
>
>The really stunning thing about the whole mess is that nobody seems to
>grasp that technically, TLDs are not in a position to restrict name
>server operators to any character sets in the domain names they use.
>After all, I can add any domain name I want to my zone files.
>
>
>
>  
>
Indeed you can.

But since the TLD registry operators can, and do, control the delegation 
of their TLDs, they have de-facto control over the sets of labels that 
can be used for second-level domain labels that are publically visible 
within their TLD domains, unless you can persuade people to point at 
your nameserver other than through the normal delegation from the root. 
This means that they can, if they so wish, apply character set 
restrictions to those labels. Your TLD registry, for example, can and 
does enforce such a policy. (http://www.denic.de/en/richtlinien.html)

On the other hand, there's nothing anyone can do to stop you resolving 
whatever labels you like on your own public nameservers, within your 
third-level, fourth-level and so on domains. However, this is unlikely 
to cause security problems for anyone apart from yourself and/or your 
customers.

 -- Neil

-- Neil