[nos-bbs] encap source IP on the bottom of the two?

[Chris Maness]

I am not sure the first post made it so here is the second try:

A note about what I am trying to do may be helpful:

I want to be able to have JNOS and Linux reach 44-net.  This was easy
in the past with encap and ISP's not being so picky about
proxy ARP for my GW Public address that I had situated on the inside
of the JNOS tun0.  Encap would automatically put the correct source
and destination addresses on the IPIP top and bottom layer (of IPIP)
with the encap interface inside of JNOS -- easy peasy lemon squezy.

Fast forward to 2022.  Now all is done with RIP, so I have tried
various tricks with some limited success.  I like amprd because
it works automagically, but it seems to ignore packets routed
to it to go to 44-net.  It maybe designed just to make Linux reach
the AMPR-net and not JNOS.  I had assumed that it would encap
anything sent to it via ip route add tools.  But I see that outbound
traffic routed to it does not come out encapsulated to eth0 it just
goes in and does nothing, or is just dropped outside the amprd0
device.  That is what I see using wireshark.

I don't know how to get amprd to unload IPIP frames that are not destined 
for one of its predefined interfaces.  Those become source IP's for my 
hosts outbound telnet connections.  It also does not seem to pack them for 
outbound travel either.  If I try to ping another 44-net host from inside 
of JNOS and route the packet to ampr0 device created by amprd, it does not 
seem to encap the outbound packet.  It just spits it out of tun0 as a RAW 
IP packet even though there are routes for fit to get picked up -- but 
maybe that is the issue with the tun0 device is that it does not 
encapsulate in an ethernet frame.  I am not sure what the amprd is looking 
for.

I have a workaround in mind.  Until I can get RIP working in JNOS, I
would just source the encap.txt for outbound encapsulation, but how to
I make the encap device lie about the source IP for the bottom IP?  It
seems to put the tun0 JNOS side IP.  I can't use my host's IP for
that.  My ISP's router only seems to like one IP mapped to any given
ethernet address.

Also, what is ec0 device in JNOS? The documentain does not go into any
detail about this other than it is the ethernet card on the host box.
Is it attached directly?  Cause that device does not exist by default.

Regards,
Chris KQ6UP DM14