John,
John C Klensin wrote:
My goal is precisely to avoid ending up with either two
standards or eight verbs. Explanation of the latter:
IPv4 IPv6 & self-referent DNS StableID
address address
RFC 959 2428 ??? ???
Verb PORT,PASV EPRT,EPSV ?DPRT,DPSV? ?IPRT,IPSV?
That seems to me excessive, if we can avoid it. So the
suggestion is whether, given that 2428 is at Proposed,
maybe it would be worth revising it, and the syntax for
EPRT and EPSV, to _permit_ use of a DNS name now and to
provide a clear extension path for a generic/stable
identifier.
There is an issue with backwards compatibility here:
Let's say we have a source host that has an implementation that allows
EPRT and EPSV to use a name as well as an address. The destination host
is a legacy host (meaning, a host implementing only 2428 as it is today,
address only). How will the destination react when receiving an EPSV
with a name instead of an address?
More generically, how will a host react when receiving an EPSV with foo
when foo is unknown? I am curious about the mechanism you envision to
determine what kind of info is being passed.
Michel.