Forward traffic to my Linode port to my home VirtualBox

VirtualBox: [2001:DB8:3759::456]:6789
192.168.1.123:6789

As I pointed out here:

https://www.linode.com/community/questions/22626/cant-ping-nodes-with-private-ip

these IP addresses belong to networks that are not routable. In particular, the IPv6 address is part of the network that is for documentation and example source code (RFC3849)…so it’s not even for operational use (this makes the IPv6 traffic on your home LAN very secure).

The VirtualBox v4 address is behind the provider's NAT, so I don't really see a way to forward packets it.

More likely both the addresses are behind a home wifi router. Also, the IP addresses of your router are dynamically allocated by your ISP so you can't count on the router having the same IP address after a DHCP lease renewal.

Thus, I think I am SOL on this plan.

That would be my assessment as well.

Spin up a nanode with Ubuntu 14.04 on it and run your app there. Linode won't care. Ubuntu won't care. Canonical extended the support life for 14.04 and 16.04 to 10 years:

https://ubuntu.com/blog/ubuntu-14-04-and-16-04-lifecycle-extended-to-ten-years

so you'll still be able to get patches & security updates for it.

-- sw

Thank you Steve. To amplify your thoughts for other readers, documentation addresses are specified in RFC3849, and should be used in documentation, but never used in live networks. I use them in threads such as this, when I want to protect my actual network addresses.

Actually, git@github.com:a-mcintosh/git-an-IPv6.git produces the fd::/8 addresses (RFC4193) from the git commit ID. This is useful when I want a few VirtualBoxes to talk to each other without eavesdroppers, and Steve's comments about routability apply to them as well.

I did spin up a 14.04, and everything on it is a go. The problem is that the Linode addresses are still receiving incoming traffic, and I want a way to respond to that traffic, or to have a 14.04 Linode.

I did spin up a 14.04, and everything on it is a go. The problem is that the Linode addresses are still receiving incoming traffic, and I want a way to respond to that traffic, or to have a 14.04 Linode.

See here:

https://linuxconfig.org/how-to-turn-on-off-ip-forwarding-in-linux

Once you set the magic sysctl parameter, you can do this with iptables.

However, this method, while relatively easy, has a caveat…depending on the nature of the traffic on port 6789 between the two nodes, forwarding it using iptables does not do so in a secure manner. You might look at setting up an ssh tunnel to handle this:

https://www.howtouselinux.com/post/exploring-ssh-port-forwarding-with-examples

You should make the tunnel two-way so the server can reply in a secure manner as well.

Actually, I would probably use a combination of the two:

• Use iptables to forward inbound/outbound traffic on port 6789 to the Linode's private IP address. The private IP address is an address in 192.168.0.0/16 (so not routable).
• Set up the tunnel between the two Linodes using the two private IP addresses as the endpoints.

This keeps the traffic between the two Linodes secure and unroutable.

You have lots of alternatives here…

-- sw