get only the unmatched list as an output

I want to know on which ports of firewalls from a particular customer the MAC Address Filtering is **not** active. So I have created 2 files: * all.txt contains a list of all firewalls of a customer and looks like this:

abc123 
    ahg578
    dfh879
    ert258
    fgh123
    huz546
    jki486
    lop784
    mnh323
    xsd451
    wqa512
    zas423

* active.txt contains a list of firewalls of the same customer in which the MAC Address filtering is active, and looks like this:

abc123: set macaddr 00:00:00:00:00:00
    ahg578: set macaddr 00:00:00:00:00:00
    dfh879: set macaddr 00:00:00:00:00:00
    ert258: set macaddr 00:00:00:00:00:00
    fgh123: set macaddr 00:00:00:00:00:00
    huz546: set macaddr 00:00:00:00:00:00
    mnh323: set macaddr 00:00:00:00:00:00
    xsd451: set macaddr 00:00:00:00:00:00
    wqa512: set macaddr 00:00:00:00:00:00
    zas423: set macaddr 00:00:00:00:00:00

I have compared the two lists using

comm -3 ~/active.txt ~/all.txt

and get this result: How can I get _only the unmatched list_ as an output? So I want the output to be only

jki486
lop784

I have tried using sdiff, grep -rL, grep -vxFf but none of them works. FYI, I'm using GNU. Linux version 3.2.0-6-amd64; gcc version 4.9.2 I would really appreciate your help! Thank you! :)