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

[Boudewijn (Bob) Tenty]

If you want to have the rip broadcast by ucsd populate the route table for ipip in Linux
you'll need to have a daemon running like, ampr-ripd what is listening for these broadcasts.
Without a daemon (and so a tunl0 interface) you will see no ipip routes in the table.  If you
want this to handled by jnos instead, you'll have to forward it jnos. All most all gateway
operators have a deamon running in Linux.

Bob VE3TOK

On 2022-12-18 11:59, Chris Maness wrote:
> 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
>
-- 
There is nothing permanent except change
  
-Heraclitus