On Feb 18, 2012, at 3:31 AM, Masataka Ohta wrote: > David Barak wrote: > >>> From: Owen DeLong o...@delong.com >> >>> Sigh... NAT is a horrible hack that served us all too well in > >> address conservation. Beyond that, it is merely a source of pain. >> >> I understand why you say that - NAT did yeoman's work in address > > conservation. However, it also enabled (yes, really) lots of > > topologies and approaches which are *not* designed upon the > > end-to-end model. Some of these approaches have found their way > > into business proceses. > > I'm afraid both of you don't try to understand why NAT was > harmful to destroy the end to end transparency nor the end > to end argument presented in the original paper by Saltezer > et. al: > > The function in question can completely and correctly be > implemented only with the knowledge and help of the application > standing at the end points of the communication system. Therefore, > providing that questioned function as a feature of the > communication system itself is not possible. > > While plain NAT, which actively hide itself from end systems, > which means there can be no "knowledge and help of the > application" expected, is very harmful to the end to end > transparency, it is possible to entirely neutralize the > harmful effects, by let NAT boxes ask help end systems. > >> An argument you and others have made many times boils down > > to "but if we never had NAT, think how much better it > > would be!" > > The reality is much better that NAT is not so harmful if NAT > clients and gateways are designed properly to be able to > reverse the harmful translations by NAT gateways. > > I have running code to make the reverse translations, with > which protocols such as ftp with PORT commands are working. > > Masataka Ohta
No, I think you do not understand... I have a NAT gateway with a single public address. I have 15 FTP servers and 22 web servers behind it. I want people to be able to go to ftp://<hostname> and/or http://<hostname> for each of them. Please explain to me how your code solves this problem? Yeah, thought so. Owen
