🚀 go-pugleaf

Frederick V. Heitkamp wrote:

> OK.  What if you wrote to the NIC (or whatever it's called) and got your
> own class C addresses for the two machines?  Would you still need to do
> the masquerading deal?  Do you still need to tell your ISP?

A whole C-class block for 2 machines ? Bit of a waste unless you are going
to use them for other things. Your ISP allocates you 1 IP (maybe dynamically)
otherwise you wouldn't be connected. You could use this 1 IP num and masquerading
to allow other hosts on your end access to the net, or, if your ISP (big if) is
co-operative you could ask for one more IP and see if they will add both IP
nums to their routing tables - this is not much good unless you have a permanent
connection though. If you have an ethernet on your end then another way is to
get a subnet allocated to you by your ISP and you can manage it as you see fit.

inet <-?-> isphost <-ppp-> yourhost-a <-ppp-> yourhost-b

Simplest case of two static IP nums allocated to you by your ISP. When you dial
in to isphost from yourhost-a you already have a default-route established by
doing something like: 

/usr/sbin/pppd /dev/cua1 38400 crtscts modem defaultroute proxyarp 123.45.67.89:

so when you ping anything other than yourhost-a or yourhost-b the packets will
flow out to isphost, fine. Now, to get yourhost-b working you need to have
isphost know about it, something like this needs to be done on isphost:

route yourhost-b gw yourhost-a dev ppp0

then on yourhost-b you need to do the reciprical:

route isphost gw yourhost-a dev ppp0

Without co-operation or root perms on isphost this is almost impossible to do
but gives you a little idea of one approach. The whole issue is extremely complex
and it would be excellent to have access to a small-time ISP C-class type FAQ
on IP routing, as most examples I've seen relate to B-class blocks.

-- 
Mark Constable (+61 7 55275724)
mailto:markc@ion.com.au
http://www.ion.com.au/linus/markc