virtualbox nataliasmode proxyonly breaks local network connectivity on windows 10

[Vipin Jain]

Hi,

I have enabled proxyonly for the nat and now for the entire local network i am unable to access the guest machine in any of the protocols. thoouh it is accessible from the internet.

Thanks, Vipin

[Klaus Espenlaub]

Could you please clarify the description? It's totally unclear what you do from where.

Also, what do you expect should happen with this very unusual configuration and why can't you use the default one?

[Vipin Jain]

Hi Klaus,

I have installed a webserver on guest ubuntu with nat enabled.

So to get the transparent IP of the client computer i have enabled nataliasmode<1-N> proxyonly for that VM.

Then after updating the NAT mode i can open the websites from internet but not from the local network computer i.e. 192.168.1.XXX.

Thanks, Vipin

[Valery Ushakov]

It's still not clear from your description what's going on.

You tell about installing webserver in the guest. How is that relevant to the fact that you cannot access other websites on the local network?

In general, what are you trying to achieve? proxyonly is a bit of a historic mistake; it probably doesn't do what you want :)

[Vipin Jain]

not other websites. the websites hosted on the webserver guest.

proxyonly is a bit of a historic mistake; it probably doesn't do what you want :)

Yes it does what is required, making client IPs available to the NAT enabled guest.

[Valery Ushakov]

Sorry, but I don't understand. Can you give a detailed specific example?

[Vipin Jain]

Ok lets see what is the structure of my server.

i have one windows machine configured as DMZ on my router. In this windows machine i have one Ubuntu VM where my webserver is installed with NAT networking forwarding webserver ports.

So to access ports from local network i cannot access it through my public IP cause it opens my router access. so i need to setup my DNS server for local networks separately where my server hosted websites resolve to the local address and not my public IP.

Now i see that on my ubuntu guest the access logs contain only aliased IPs i.e. 10.0.0.2. So i decided to switch to transparent IPs for NAT by enabling nataliasmode for that network connection to proxyonly. Now i successfully have my access log with actual client IPs and not 10.0.0.2.

But now i cannot access any port forwarded on that ubuntu VM from local IPs i.e. 192.168.1.XXX.

I believe this makes everything clear.

Thanks, Vipin

[Valery Ushakov]

Thanks. That does make everything clear. However I can't seem to reproduce the problem. I can connect to the forwarded ports from another machine on the local network just fine. Are you sure you split-brain dns has the correct address for the host machine, i.e. do clients from the local network try to connect to the right destination?

Can you capture traffic for the failing connection with wireshark/tcpdump on both guest and host?