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

[maiko at pcsinternet.ca]

IF you have a static IP address, and it's listed in your gateways entry,
you can use something like this to send ALL incoming IPIP packets direct
to JNOS via the tun interface between JNOS and linux :

    iptables -t nat -A PREROUTING -i eth0 -p 4 -j DNAT --to-destination 
192.168.200.201

In the above example 192.168.200.201 is the JNOS SIDE of the tun 
interace.

Of course my JNOS does the IPIP, not linux. You could probably use a 
form of the
above as well if all you want is just the RIP packets and nothing else ?

Not sure why I am posting this though, since I have the feeling you 
don't have
a static IP address at your disposal, so what Bob mentioned probably 
applies.

Maiko

On 2022-12-18 18:08, Chris Maness wrote:
> Totally got that.  I have that daemon compiled.  I just wanted to see
> if I could just pipe the RIP into JNOS with IPtables.  I may do it
> that way, but feel compelled to try to figure out what went wrong with
> my first idea as I would like to have a better understanding of
> IPtables.
> 
> Chris KQ6UP
> 
> On Sun, Dec 18, 2022 at 2:44 PM Boudewijn (Bob) Tenty <bob at tenty.ca> 
> wrote:
>> 
>> Oops, I mean to jnos
>> 
>> On 2022-12-18 17:39, Boudewijn (Bob) Tenty wrote:
>> > 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
>> 
>> 
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