I’m not sure I understand how you’d shred your fingers on them. I put my nail under the tab and lift until my finger can get under it

Sorry, I was looking more specifically at that DNAT rule

8   480 DNAT       6    --  *      *       0.0.0.0/0            0.0.0.0/0            tcp dpt:2222 to:192.168.101.4:22

That rule exists in the host 192.168.86.73, correct? And from the guest, 192.168.101.4 you are attempting to ssh into 192.168.86.73:2222?

It might not be your issue (or only issue), but that DNAT rule says that if a connection comes in on port 2222, instead send it to 192.168.101.4:22. So 192.168.101.4->192.168.86.73:2222->192.168.101.4:22. I would have thought you’d want it to be a DNAT to 192.168.86.73, functionally doing port bending, so it goes 192.168.101.4->192.168.86.73:2222->192.168.86.73:22.

That doesn’t explain the connection refused, though, based on what you’ve said; there’s some fringe possibilities, but I wouldn’t expect for your setup if you hadn’t said (like your ~/.ssh/ssh_config defining an alternate ssh port for your guest OS than 22). It’s somewhat annoying, but it might be worthwhile to do a packet capture on both ends and follow exactly where the packet is going. So a

tcpdump -v -Nnn tcp port 22 or tcp port 2222

For general awareness, not all flags can match all parts of an iptables command; the part you included there with “–to offset” is only valid with the string module, and not the DNAT action. That said after playing around with it a little, iptables actually does short flag matching, so ‘DNAT --to 1.2.3.4’ ‘DNAT --to-d 1.2.3.4’ and ‘DNAT --to-destination’ are all equivalent, so not the source of your issue.

I am having trouble following the IP scheme, though. Is your Alma guest 192.168.101.4, or is that the host IP? If it’s Alma’s and you are attempting to ssh from that IP to the host with that iptables rule, what should happen is that DNAT would then redirect that connection back to Alma. If the guest doesn’t have a :22 listener, you’d get a connection refused from itself.

Your hook has

/sbin/iptables -t nat -I PREROUTING -p tcp --dport $HOST_PORT -j DNAT --to $GUEST_IP:$GUEST_PORT

But I’d didn’t think that “–to” was a flag for DNAT, I thought it was “–to-destination”

If you ‘iptables -nvL’ and ‘iptables -t nat -nvL’ do you see both your DNAT and forwarding rules (although if the default is ACCEPT and you don’t have other rules, the FORWARD one isn’t needed), and do you see the packet count for the rules increase?