My Macbook can connect to ethernet over Ubuntu but not OS X I'm currently dual booting Ubuntu 14.04 and OS X Mavericks (10.9.4) on my 2014 Macbook Pro. When running Ubuntu, I can plug in the Ethernet cable and instantly be connected. But when running OS X, there's no Ethernet connection detected.

Since I was able to connect on Ubuntu instantly, I shouldn't have the issue of having to set up additional configurations, such as a PPoE connection. Since I'm dual booting I'm obviously also using the same laptop, the same Ethernet cable, and the same Ethernet port so it doesn't seem like there should be a hardware issue either.

What could be the issue here?



When I run "ifconfig" in my terminal while booting OS X, this is what I get:

lo0: flags=8049&lt;UP,LOOPBACK,RUNNING,MULTICAST&gt; mtu 16384
    options=3&lt;RXCSUM,TXCSUM&gt;
    inet6 ::1 prefixlen 128 
    inet 127.0.0.1 netmask 0xff000000 
    inet6 fe80::1%lo0 prefixlen 64 scopeid 0x1 
    nd6 options=1&lt;PERFORMNUD&gt;
gif0: flags=8010&lt;POINTOPOINT,MULTICAST&gt; mtu 1280
stf0: flags=0&lt;&gt; mtu 1280
en0: flags=8863&lt;UP,BROADCAST,SMART,RUNNING,SIMPLEX,MULTICAST&gt; mtu 1500
    ether 80:e6:50:16:b0:c0 
    inet6 fe80::82e6:50ff:fe16:b0c0%en0 prefixlen 64 scopeid 0x4 
    inet 192.168.70.245 netmask 0xffffff00 broadcast 192.168.70.255
    nd6 options=1&lt;PERFORMNUD&gt;
    media: autoselect
    status: active
en1: flags=8963&lt;UP,BROADCAST,SMART,RUNNING,PROMISC,SIMPLEX,MULTICAST&gt; mtu 1500
    options=60&lt;TSO4,TSO6&gt;
    ether 72:00:05:04:94:20 
    media: autoselect &lt;full-duplex&gt;
    status: inactive
en2: flags=8963&lt;UP,BROADCAST,SMART,RUNNING,PROMISC,SIMPLEX,MULTICAST&gt; mtu 1500
    options=60&lt;TSO4,TSO6&gt;
    ether 72:00:05:04:94:21 
    media: autoselect &lt;full-duplex&gt;
    status: inactive
bridge0: flags=8863&lt;UP,BROADCAST,SMART,RUNNING,SIMPLEX,MULTICAST&gt; mtu 1500
    options=63&lt;RXCSUM,TXCSUM,TSO4,TSO6&gt;
    ether 82:e6:50:61:cb:00 
    Configuration:
        id 0:0:0:0:0:0 priority 0 hellotime 0 fwddelay 0
        maxage 0 holdcnt 0 proto stp maxaddr 100 timeout 1200
        root id 0:0:0:0:0:0 priority 0 ifcost 0 port 0
        ipfilter disabled flags 0x2
    member: en1 flags=3&lt;LEARNING,DISCOVER&gt;
            ifmaxaddr 0 port 5 priority 0 path cost 0
    member: en2 flags=3&lt;LEARNING,DISCOVER&gt;
            ifmaxaddr 0 port 6 priority 0 path cost 0
    nd6 options=1&lt;PERFORMNUD&gt;
    media: &lt;unknown type&gt;
    status: inactive
p2p0: flags=8843&lt;UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST&gt; mtu 2304
    ether 02:e6:50:16:b0:c0 
    media: autoselect
    status: inactive


After reinstalling OS X I can no longer see the rEFInd screen and thus cannot boot Ubuntu. However, I remember when I ran "ifconfig" earlier I saw an item that started with "eth0"
If you can see the interface in /Utilities/System Configration > "Ethernet Cards", try creating a new network location.

If the issue persists in a new location, you can reset OS X's detected network interfaces by (re)moving /Library/Preferences/SystemConfiguration/NetworkInterfaces.plist.  If you want to play it absolutely safe, you could (re)move the entire SystemConfiguration folder, but this will affect other settings (like custom network authentication, power management settings, etc.). NOTE: this step supersedes testing it in a new user since it removes global preferences (which affect every user).

If you're still not seeing it, try booting to your Recovery Partition, launching Terminal, and running ifconfig to see if the Recovery partition can see the network interface.  If the Recovery Partition sees it, a reinstall of OS X might be needed.  If it doesn't, well then you did something that I've never seen... :)