While bringing my self-made ESXi hosts into service I saw that only one of two network cards was detected. The reasons for this issue was that VMware ESXi offers no driver for the second network card Intel 82579LM.
The software packages just needs to be transfered to a datastore the ESXi host has access to before it can be installed. You also need to make sure that installing VIB packages that are not signed by VMware is allowed (community-supported):
# esxcli software acceptance set --level=CommunitySupported # esxcli software vib install -v /vmfs/volumes/VOLUME/net-e1000e-2.3.2.x86_64.vib
After a system reboot two network cards can be used: