El Capitan

[Michael Zacherl]

On 13.Oct 2015, at 9:35 , K9 Kai Niggemann <canine at waf80.de> wrote:

>> But, SIP prevents my mobile data stick to work.
>> Since it's out of production I don't think any signed drivers will show up.
> 
> What is SIP?

System Integrity Protection.
Basically a security layer in the system kernel which prevents even root (the now former almighty superuser) to alter system files, such as drivers. With SIP active (which is by default for a reason) only the system itself (vaguely speaking) can modify its files.
3rd party kernel extensions (such as drivers) which are not signed won't be loaded at all.
Like the drivers for my ZET MF180 mobile data stick:
10.10.2015 15:36:30,000 kernel[0]: USBMSC Identifier (non-unique): MF1800ZTED010000 0x19d2 0x2000 0x0, 2
10.10.2015 15:36:31,256 com.apple.kextd[52]: Untrusted kexts are not allowed
10.10.2015 15:36:31,256 com.apple.kextd[52]: ERROR: invalid signature for com.ZTE.driver.ZTEUSBMassStorageFilter, will not load

It's possible to disable SIP when booting from the recovery partition, but it's not recommended for obvious reasons: for one it is a solid security feature (which actually remains to be proven) and also it's foreseeable that such a feature will become manifest over the c(o)urse of forthcoming OS X versions. 
I.e. you won't be able to disable it anymore. So to adapt and get used to it is likely the best strategy - if one decides to stick with OS X. ;) 
m.

--
http://mz.bluemole.com