[tproxy] netcat for tproxy (and additional noob questions)

[John Lauro]

> I have a very simplistic patch for netcat here:
> 
> http://home.sch.bme.hu/~piglet/netfilter/tproxy/netcat-ip_transparent-
> support.patch

I think I came across that patch before.  The problem is I can not find that
version (1.10) of netcat anywhere.  Found some places that mention being
pointers to it, but dead links...  It appears there a new GNU version that
has lower version number, and also a BSD version, but it is way different
too (or at least different enough that the patch doesn't apply).

 
> 
> Reusing the original port is usually a bad idea. A notable example of
> things breaking is Netfilter connection tracking, which gets confused
> if
> you reuse the exact same endpoints for a different connection.

Technically they are not the exact same if you include the interface.  If it
doesn't consider the interface then they would appear the same.