Ubuntu - how to ignore dns and default route on all but one?


  • https://serverfault.com/questions/674731/multiple-dhcp-uplinks-how-to-ignore-dns-and-default-route-on-all-but-one
  • https://serverfault.com/a/674738

(I am still interested in solutions that only touch /etc/network/interfaces{,.d/}, but not /etc/dhcp/. In the absence of such solutions, I use this one.)

In /etc/dhcp*/dhclient.conf, remove the options routers, domain-name-servers, domain-name, domain-search from the global request statement. Then add this (assuming eth0 is the device where default route and DNS shall not get ignored):

interface "eth0" {
    also request routers, domain-name-servers, domain-name, domain-search;

This solution works at least for isc-dhcp-client version 4.2.2.dfsg.1-5+deb70u8 as it is shipped with Debian 7. I assume it works for later versions too.


Confirmed that the original idea works with minor changes (eth0 must be quoted, and it should be request, not required) Specified the dlclient version this works for