How can I have a bridge that uses DHCP?

Question

I have set up a linux box (centos 7) to use for virtualizing some servers. I have set up a bridge, but I need to do it with DHCP, but it doesn't seem to like it. The reason I need DHCP is because static IP addresses don't seem to go through my crap xfinity cable router. Sometimes they can talk with the other computers, but I can't access the internet at all.

Yes this box needs a static IP; I have set it up in the router, but it needs to do DHCP to get it.

I have also tried setting up a static IP on the bridge and then having a subinterface that gets a dhcp IP, but it didn't seem to want to work; however, I was able to get a DHCP interface with a static subinterface to work on another computer (debian--of course I haven't restarted this computer yet, and that might break everything).

Any suggestions? Would adding some static routes help? I tried a few and they didn't seem to work, but I may have just not been doing them right.

Answer 1

It should be possible to run dhclient br0 to request a DHCP lease and assign the IP to the bridge.

Your cable router (or actually: your ISP's infrastructure) probably needs you to do a DHCP request to fix the routing of your IP address, even if you have a static IP; I've seen that before. In some cases using dhcping may help to "fake" the DHCP request so that routing works.