DHCPd using wrong interface

glenn.satchell at uniq.com.au glenn.satchell at uniq.com.au
Tue Dec 22 08:07:49 UTC 2020


Hi Dan

Which bind server is it trying to update? Those updates are sent as 
unicast packets and are subject to normal routing rules. Perhaps it's 
trying to update the ISP's DNS server?

Can you use tcpdump to see what the destination IP address is?

regards,
Glenn

On 2020-12-19 18:23, Dan Egli wrote:
> I am completely stumped on how to solve this one. I have a machine
> with two NICs. It's my gateway machine between my home private LAN and
> the internet. The gateway machine has enp0s3 with an address of
> 10.0.2.15 as it's world facing address (yes, my ISP wants to run
> everything through NAT. Don't ask me why). The LAN address range is
> `192.168.10.0/24 on enp0s8.  I configured dhcpd to completely ignore
> anything coming from 10.0.0.0/8, and I even have enp0s8 listed on the
> command line (and NOT enp0s3). Yet when dhcpd tries to send update
> requests to bind, it keeps using the 10.0.2.15 address, which bind
> properly refuses to listen to. How do I make dhcpd send messages from
> enp0s8's 192.168.10.2 address vs the 10.0.2.15 address?


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