interfaces: spoofed MAC should be compared as case insensitive

[stormy1777]

Full details here:

https://forum.opnsense.org/index.php?topic=4328.0

In short, if MAC address is set to any valid value in Interfaces[WAN] page and that type is PPPOE, then network only works after a reboot. There after pressing the PPPOE disconnect button and connect, produces unstable system, no internet, and frequently two mpd5 processes running in the background, ping delays in excess of 2 seconds on the wan network (to the adsl modem).

Workaround: leave MAC field Empty on pppoe wan interface!!

Not confirmed by others yet, but on my box, reproduced on 16.7 & 17.1RC1, reimaged several times to confirm this.

The issue kept happening even if interface_ppps_configure in interfaces.inc was disabled, placed sleep(100000); at top of it.. so clearly some other mechanism was not liking that MAC address setting on the pppoe interface. Reproduces every time on my side. Also ran test with power cycling the ADSL modem several times to "honor" the set MAC address, to no avail. Only working system was without a MAC set.

[AdSchellevis]

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