[Mimedefang] [Patch] relay_is_* not ipv6 friendly

Michiel Brandenburg apex at xepa.nl
Tue Feb 2 14:44:48 EST 2010

On 2-2-2010 19:01, David F. Skoll wrote:
> In other words, what is the difference between an SMTP client coming
> from "::ffff:" or "" ?
or ::ffff:c0a8:a01. Well not a lot I would guess except that one is ipv6 
the other ipv4.  Guess it all depends on semantics .. probably nothing 
functional but I thought I would bring it up.

> I made the C code recognize mapped IPv4 addresses and convert them to
> plain IPv4 addresses to simplify the filter code.  If you get an IPv4
> address, fine... you can handle it.  Similarly, if you get an IPv6
> address, you don't need to worry about the (IMO hackish and ugly)
> IPv4-mapped special case.
No questions remarks there :)

>> Say you are on a ipv4 only network you would never receive those
>> addresses while if you are on a ipv6 only network all of a sudden you
>> might get data from an ipv4 address (but you are ipv6 only), that might
>> throw a spanner in the works.
> How so?
Well database and code could only assume that they get ipv6 addresses. 
But then I guess there is no one stopping you encoding all ipv4 as 6 :) 
and I guess we can revisit when more of the world is using ipv6 .. like 
in 100 years :)

> I doubt any RBL would list the IPv6-variant without also listing the
> IPv4 variant.
I have yet to use RBL's that even deal with ipv6 let alone ipv4 mapped 

I will see when I can get the patch altered not to take into account the 
ipv6 mapped ipv4, as the c code handles that part.

Michiel Brandenburg

More information about the MIMEDefang mailing list