There are two ways. 1) change bind-interfaces to bind-dynamic. It is able to wait until requested address/interface becomes available.
2) change systemd unit, add After=network-online.target to dnsmasq [Unit]. Starts dnsmasq after network interfaces are configured. Cheers, Petr On 2/13/22 18:20, 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. > > It works OK on Raspberry Pi systems but apparently not on a pretty > standard ubuntu Linux system. > > When I try to start dnsmasq I get this error:- > > root@esprimo# systemctl status dnsmasq.service > × dnsmasq.service - dnsmasq - A lightweight DHCP and caching DNS server > Loaded: loaded (/lib/systemd/system/dnsmasq.service; enabled; vendor > preset: enabled) > Active: failed (Result: exit-code) since Sun 2022-02-13 16:56:27 > GMT; 1min 46s ago > Process: 3839 ExecStartPre=/etc/init.d/dnsmasq checkconfig > (code=exited, status=0/SUCCESS) > Process: 3847 ExecStart=/etc/init.d/dnsmasq systemd-exec > (code=exited, status=2) > CPU: 19ms > > 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. > > Does the error mean that Ubuntu Linux isn't among "systems which support it"? > > Is there any other way to get the result I want? That is dnsmasq running but > not > actually being visible as a server on the LAN until I do something to "switch > it > on"? > -- Petr Menšík Software Engineer Red Hat, http://www.redhat.com/ email: pemen...@redhat.com PGP: DFCF908DB7C87E8E529925BC4931CA5B6C9FC5CB _______________________________________________ Dnsmasq-discuss mailing list Dnsmasq-discuss@lists.thekelleys.org.uk https://lists.thekelleys.org.uk/cgi-bin/mailman/listinfo/dnsmasq-discuss
