2009/4/15 Nathaniel W Filardo <n...@cs.jhu.edu>: > On Wed, Apr 15, 2009 at 02:03:35PM +0200, Patrick Kristiansen wrote: >> I'm thinking of writing a NAT implementation for plan 9. > > I would suggest instead that it might be easier to write an adaptor program > for non-Plan 9 hosts which made their network stacks talk to a /net. That > is, you'd want a program which spoke TAP/TUN out one end to the host kernel > and out the other dialed and imported /net from the Plan 9 gateway. AFAIK > TAP/TUN-like things exist on most OSes, and there's good example code in > OpenVPN (for example).
It's not simpler, requiring N implementations for heterogeneity, where N is the number of non-Plan 9 hosts you support. Certainly Windows, Linux, OS X, and FreeBSD would all need separate implementations. OS X doesn't have a tap(4) device per default, and Windows needs a driver as well. Of course some code can be shared, but I believe this will simply lead to bloat. If we want Plan 9 to work with other operating systems, let's make it work with other operating systems... I don't think forcing everyone else to conform to us is the right answer, in this case. NAT is well-defined, well-understood, and honestly not that difficult to implement. > The program would have to know enough about the on-the-wire representation > of TCP/IP and UDP/IP to do connection tracking etc. (much like NAT, I > suppose) but the advantage is that it wouldn't impact the Plan 9 kernel. NAT can be implemented in userland in Plan 9 as is. > --nwf; > > P.S. This idea shamelessly stolen from vsrinivas, but he's mailing-list shy. Not trying to come off as catty, I just don't think this is a practical idea. Might be a fun project, nonetheless. --dho
