[nos-bbs] Not Sure if my IPtables forwarding RIP is working

[Chris Maness]

I cross posted this on Reddit (I am disclaiming that fact as if it is
a sin, but don't know why it is a bad thing).  Read virtual host on
virtual lan tun/tap tun0 as JNOS and 4.3.2.1 as my GW address that is
on eth0 of this machine.

I thought I had this right, but I am not seeing packets on the TUN/TAP
device to the virtual lan. The host that needs RIP2 data is on
192.168.2.1 using the tun0 TUN/TAP on a Linux host. I am using
wireshark to see weather RIP is making it to TUN/TAP, but not sure I
understand that device correctly. I was thinking that I can see RIP
frames come in on eth0 and then subsequently see them on tun0 as it is
listed in wireshark. However, as I was composing this post, I realized
that the RIP packet may not need to be retransmitted on tun0 because
it acts like a wiretap on eth0 so would not need to have any frames
retransmitted on it, but I am not certain in this behavior. However,
the bottom line is RIP does not seem to be populating tables on the
192.168.2.1 host. Public IP's in my example here has been obfuscated
by 4.3.2.1 -- take that as an IP exposed to the wild. Here are my
IPTABLES commands:
# iptables -t nat -A PREROUTING --dst 4.3.2.1 -p udp --dport 520 -j
DNAT --to-destination 192.168.2.1
# iptables -t nat -n -L
Chain PREROUTING (policy ACCEPT)
target prot opt source destination
DNAT udp -- 0.0.0.0/0 4.3.2.1 udp dpt:520 to:192.168.2.1
Chain INPUT (policy ACCEPT)
target prot opt source destination
Chain OUTPUT (policy ACCEPT)
target prot opt source destination
Chain POSTROUTING (policy ACCEPT)
target prot opt source destination
###
I hope that is clear as to what I am trying to accomplish, and weather
or not this should work.
Thanks in advance,
Chris KQ6UP

-- 
Thanks,
Chris Maness