How can I set the destination to "anywhere" in the iptables?

Solution 1:

You can omit the "-d ...", but INPUT is just to your local device.

When your destination is in another network (even if it is a virtual network) you need forwarding:

echo 1 > /proc/sys/net/ipv4/ip_forward

And the FORWARD chain is the right place to put your rules (but "ACCEPT" should already be the default)

Hint: iptables -S outputs the rules in the command-format