outgoning-interface

[Stuart Henderson]

On 2020/02/18 12:55, Dysmas de Lassus via Unbound-users wrote:
> Hello Andreas,
> 
> in your last answer to Sheikh Muhammed Ayub you write :
> 
> outgoing-interface: 192.168.64.131
> 
> -> if you have only one non loopback address, you don't need this
> 
> 
> 
> The meaning of this parameter has always been unclear for me. I read several
> times the doc, but it remains obscure. The question is practical :
> 
> I have three interfaces : eth0, eth1 and wlan0. eth1 and wlan0 are connected
> to the LAN, so the only outgoing interface is eth0. Presently, I have no
> "outgoning-interface" in my configuration, and unbound works very well
> without it, but perhjaps at the cost o f a slowdown ? Giving a value to this
> parameter is uneasy since eth0 is in DHCP (and must be in DHCP when the
> device is a mobile). Perhaps this parameter was added for more complex
> networks. Presently I don't use it, I wanted only to know if it is OK like
> that. Thanks.
> 
> Dysmas
> 
> 

It is usually totally OK to not set outgoing-interface and with your
setup using DHCP that's exactly what you want.

You may need it if you have multiple addresses on a machine and it
doesn't pick the right one by default (normally for IPv4 the OS will
select the address that matches the route used to send the packet, which
is normally but not always what you want).

Also if you have multiple static external addresses then you can set
this to multiple addresses and in that case unbound will select from all
of them randomly - this makes it harder for someone to blindly spoof
replies.