[Dnsmasq-discuss] Is there any way found this "Cannot assign requested address"?

[Matus UHLAR - fantomas]

On 13.02.22 17:20, Chris Green wrote:
>I want to configure a system to listen on an address that it doesn't
>actually have until I add the address to the network interface.

https://duckduckgo.com/?q=linux+bind+foreign+IP&t=seamonkey&ia=web

on linux you should set net.ipv4.ip_nonlocal_bind=1

>    Feb 13 16:56:27 esprimo systemd[1]: Starting dnsmasq - A lightweight DHCP and caching DNS server...
>    Feb 13 16:56:27 esprimo dnsmasq[3847]: dnsmasq: failed to create listening socket for 192.168.1.2: Cannot assign requested address
>    Feb 13 16:56:27 esprimo dnsmasq[3847]: failed to create listening socket for 192.168.1.2: Cannot assign requested address
>    Feb 13 16:56:27 esprimo dnsmasq[3847]: FAILED to start up
>    Feb 13 16:56:27 esprimo systemd[1]: dnsmasq.service: Control process exited, code=exited, status=2/INVALIDARGUMENT
>    Feb 13 16:56:27 esprimo systemd[1]: dnsmasq.service: Failed with result 'exit-code'.
>    Feb 13 16:56:27 esprimo systemd[1]: Failed to start dnsmasq - A lightweight DHCP and caching DNS server.


>In the dnsmasq man page it has:-
>
>    -z, --bind-interfaces
>          On  systems  which support it, dnsmasq binds the wildcard address, even when it
>          is listening on only  some  interfaces.  It  then  discards  requests  that  it
>          shouldn't reply to. This has the advantage of working even when interfaces come
>          and go and change address. This option forces dnsmasq to really bind  only  the
>          interfaces  it is listening on. About the only time when this is useful is when
>          running another nameserver (or another instance of dnsmasq)  on  the  same  ma‐
>          chine.  Setting  this  option  also enables multiple instances of dnsmasq which
>          provide DHCP service to run in the same machine.
>
>I thought this would mean I could do what I want which is to have:-
>
>    listen-address=192.168.1.2,127.0.0.1
>
>... and only actually create the IP 192.168.1.2 on the network interface
>when I want this system to be the DHCP/DNS server.

no, this affects how dnsmasq calls bind(), not how bind() will respond.

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