[COFF] UUCP on macOS / *BSD

[gtaylor at tnetconsulting.net (Grant Taylor)]

On 6/28/20 6:50 PM, Grant Taylor wrote:
> Does anyone have any experience with UUCP on macOS or *BSD systems that 
> would be willing to help me figure something out?

I ended up getting this to work.

I don't know if it was a macOSism or a *BSDism, but the root of the 
problem was crossing between users via setuid / setgid in relation to 
OpenSSH.

Two different versions of macOS behaved differently.

macOS Yosemite 10.10.5 runs the underlying ssh pipe command as the user 
account that initiates the uucp / uuto / uux.

macOS Catalina 10.15.15 runs the underlying ssh pipe command as the 
_uucp user, NOT the account that initiates the uucp / uuto / uux.

As such, on macOS Yosemite 10.10.5, I have to have the normal user's ssh 
public key in the authorized_keys file on the remote system.

Conversely, on macOS Catalina 10.15.15, I have to have the _uucp user's 
ssh public key in the authorized_keys file on the remote system.

I don't know why macOS Yosemite 10.10.5 and macOS Catalina 10.15.15 are 
behaving differently, but they are.

These inconsistencies made identifying which client ssh config file -- 
nominally ~/.ssh/config -- was used cumbersome.

For some unknown reason, I couldn't rely on "~/" or defaults to specify 
the _uucp user's key (Identity) file or the known_hosts file on macOS 
Catalina 10.15.15, despite the fact that it was running as the _uucp 
user.  I ended up having to hard code the paths, as they were defaulting 
to the original user account that initiated the uucp / uuto / uux.

I can only surmise that something is fundamentally different between 
Linux and macOS in how it does things when changing user accounts via 
setuid & setgid as I did not have any of these problems on multiple 
Linux machines.  I can further surmise that something is different 
between macOS Yosemite 10.10.5 and macOS Catalina 10.15.15.  I don't 
know if this is related to System Integrity Protection or something else.



-- 
Grant. . . .
unix || die

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