Port Blocked

[Thomas B.]

I have a Windows 10 VM on Nethserver/Centos using bridged Network.
I try to join the Samba Domain, but it doesn't work.
After hours of finding a mistake I found the following:
I can access the DNS Server on the Nethserver, but not the DNS Server on the Samba NSDC Instance:
telnet 192.168.0.1 53 (main machine and dnsmasq dns server) works
telnet 192.168.0.2 53 (nsdc machine with samba) connection error

Issuing the same commands from a physical Windows 10 works.

Why are ports from the vm blocked on a bridged network? After all reading this ist actually not possible.
How can I find out, why and who it's blocked
Thomas

[scottgus1]

Bridged typically connects to the network stack before the host firewall, at least on Windows hosts, so the host's firewall should not interfere between the LAN and the guest.

Bridged itself contains no port blocking or firewall settings in Virtualbox. It's an open highway.

Bridged puts the guest on the same LAN as the host, side-by-side. To the host the guest looks like another computer on the LAN. So you might need to open ports in the host firewall to allow the guest to see the host's services. See Virtualbox Networks: In Pictures: Bridged Adapter.

On Windows hosts, there are ports that need to be open for file sharing and shared folders. Maybe the same for Linux hosts? Not a Linux guru here, just Windows...

[Thomas B.]

Thats exactly how I understood the bridged concept.
That's why I don't understand why I can't access the other DNS server.
I tried a second VM Windows Image with the same result.
Anybody else has some glues?

[scottgus1]

First check that all the firewalls allow ICMP echo request, then check to see if you can ping the destination's IP address. If you can ping, then the Virtualbox network is working and the issues are in the OS's involved, not in Virtualbox.

The only networks Virtualbox provides that have a "port-forwarding" (and therefore port blocking, ie rudimentary firewall) are NAT and NAT network.