I have reviewed this document as part of the security directorate's ongoing effort to review all IETF documents being processed by the IESG. Document editors and WG chairs should treat these comments just like any other last call comments. This draft is about trying to secure access to IPv4 FTP servers from IPv6 clients. The results are not terribly encouraging but I find they are quite accurately described in the Security Considerations Section and I don't think you could do much better given a requirement to work with existing FTP servers. I have a bit of a problem with the title ("An FTP ALG for IPv6-to-IPv4 translation") and the slant of some of the wording. It claims to be able to describe, as an Application Level Gateway, various recommendations which are then combined with a separate existing IPv6-to-IPv4 ALG. It talks about multiple ALGs being implemented at a single entity that are handling an single FTP session. This just all seems very odd to me as it isn't very clear what the interface between these different ALGs all somehow cooperating on one session is. I believe, in reality, anyone implementing this will take an existing ALG and modify it as suggested in the draft. The draft would therefore make more sense if written as suggested changes to a single ALG rather than as an additional ALG that is somehow compounded with an existing FTP ALG... Just my opinion. Thanks, Donald =============================  Donald E. Eastlake 3rd   +1-508-333-2270 (cell)  155 Beaver Street  Milford, MA 01757 USA  d3e3e3 at gmail.com