/dev/ttyS0 permission error

[Mikkel L. Ellertson]

Jay Cliburn wrote:
> Mikkel L. Ellertson wrote:
>> The difference is
>> probably in the settings of console permissions. (man console.perms)
> [snip]
>> Now, if you want the user that is logged into the console to be able
>> to use the serial ports, you could probably do something like create
>> a file /etc/security/console.perms.d/10-serial.perms with something
>> like:
>>
>> # Serial port rules.
>> <serial>=/dev/ttyS*
>>
>> <console>  0660 <serial>     0660 root.uucp
>>
>> If you just want to control /dev/ttyS0 then change ttyS* to ttyS0.
> 
> I looked at console.perms after seeing a reference to it during my web
> search. In FC6, anyway, there's no rule for serial ports.
> 
I should have explained this better. FC5 (and FC6?) do not use
console perms to control serial ports. But some other distributions
do. I know that Mandriva does, and I have run into other that do,
but I am not sure which ones.

> [jcliburn at osprey ~]$ egrep ^[^#] /etc/security/console.perms
> <console>=tty[0-9][0-9]* vc/[0-9][0-9]* :[0-9]\.[0-9] :[0-9]
> <xconsole>=:[0-9]\.[0-9] :[0-9]
> 
> Is there a rule governing serial ports in FC5?
> 
No, there is not a rule in FC5. That is why I said you might want to
add one in FC6. It is more secure then letting everyone access it.
The disadvantage is that you can not access the port(s) when
connecting remotely. If you need that type of access, then adding
the user to the uucp group works better.

One thing to keep in mind is that if FC5 and probably FC6, most of
the rules are in the /etc/security/console.perms.d directory, and
not the /etc/security/console.perms file. This lets you add local
rules that do not get overridden if the package gets upgraded.

Mikkel
-- 

  Do not meddle in the affairs of dragons,
for thou art crunchy and taste good with Ketchup!