I'm on 10.9, and I had been using internet sharing successfully again for the first time since Lion. Today though, it just decided to stop working again.
Modem -ethernet-> Router -ethernet-> Mac Pro -ethernet-> MacBook Pro Retina
The internet works fine on the Mac Pro, but it is no longer forwarding the proper DHCP settings to the MacBook.
Previously, the MacBook would get the IP address of 192.168.2.12, and was able to surf the web fine. (Though it wasn't able to connect to any AirPlay/AirPrint devices while on the ethernet interface)
Sometime today, a setting got messed up, and I'm not sure how to fix it or what setting it is.
The MacBook now has a "Self-assigned" IP of 169.254.121.24, even though it is set to use DHCP. The ethernet port on the Mac Pro that the MacBook Pro is connected to is showing a "Self-assigned" IP of 169.254.36.53, even though it is set up to use DHCP as well.
The internet sharing options appear to be correct: share connection from Ethernet 1 to Ethernet 2.
But alas, for no apparent reason, I'm not getting internet access.