Surprisingly: # lspci -vvv | grep 'Device Serial Number' Capabilities: [140 v1] Device Serial Number 00-1e-67-ff-ff-7f-9c-98 Capabilities: [140 v1] Device Serial Number 00-1e-67-ff-ff-7f-9c-98 Capabilities: [140 v1] Device Serial Number 00-1e-67-ff-ff-7f-9c-98 Capabilities: [140 v1] Device Serial Number 00-1e-67-ff-ff-7f-9c-98 Capabilities: [148 v1] Device Serial Number 00-1e-67-03-00-81-37-0c Capabilities: [140 v1] Device Serial Number 90-e2-ba-ff-ff-46-ef-30 Capabilities: [140 v1] Device Serial Number 90-e2-ba-ff-ff-46-ef-30 So for mentioned eth1 which should have MAC 00:1e:67:7f:9c:99 there is no entry in lspci but for all 4 ports of Intel I350 the MAC in lspci seems to be the same :) First four lines above are for Intel I350 ethernet adapter and I suspect that some settings in bios could change due to some unknown reason, I will check this. BR, Rafal.