Opened 2 years ago
#21006 new defect
DHCP provides wrong DNS server address if DNS server address is not requested
| Reported by: | JiriS | Owned by: | |
|---|---|---|---|
| Component: | network/NAT | Version: | VirtualBox 6.1.34 |
| Keywords: | Cc: | ||
| Guest type: | other | Host type: | other |
Description
VirtualBox 6.1 on Fedora Linux with NAT networking:
If the DHCP client in the VM does not provide option 55 - Parameter Request List - or does provide one, but does not provide Item 6 - Domain Name Sever - in DCHDISCOVER, then the VirtualBox builtin DHCP server will respond with a DHCPOFFER containing a DNS Sever option, anyway.
But the address specified in this option will be invalid. More specifically, instead of providing 10.0.2.3, it will provide whatever is in /etc/hosts. This may go unnoticed if the DNS sever listed in /etc/hosts has a routable address.
On a Fedora Linux the DNS server in /etc/hosts has the address 127.0.0.53, which is not routable and as such when the VM tries to talk to it, it fails (it has no such local address configured).
Interestingly, if I manually configure the DNS server address in the guest OS to 10.0.2.3, the VirtualBox DNS server does not respond on that address.
I can reproduce this on HelenOS as of Git revision 52214a2d97559c2396ecbcd3de80863dab438fb3. Unfortunately this cannot be tested with a binary release (e.g. the latest, HelenOS 0.11.2) as it misses a fix for another problem that HelenOS DHCP has in VirtualBox.
