Best Practice for Allowing non-root Users Access to Serial Port?

[Roland Smith]

On Fri, Apr 01, 2005 at 11:17:14AM -0600, Martin McCormick wrote:
> 	What is the safest way to let non-root users access
> /dev/ttyd0?  I notice that in FreeBSD, /dev/ttydx is owned by
> root:wheel.  In linux, the ttySx's are in a special group so the trick
> there is to add users to that group and make sure the ttyS's are group
> writable.
> 
> 	Here, I want the users to be able to use C-kermit to talk to a
> remote device without them having to be root.

Since you want to dial out, I think you'll need to use /dev/cuaa*.

Making kermit users members of a group, and have that group own
/dev/cuaa* with read/write privileges seems like a good idea.

For instance, create a group "kermit" with 'pw groupadd kermit'. Then
you can use devfs(8) to change the ownership and permissions of the
relevant device: "devfs rule add path 'cuaa*' mode 0660 group
kermit". This setting will not survive a reboot, so you'll have to add the
following to /etc/devfs.rules: "add path 'cuaa*' mode 0660 group kermit".

Now add the relevant users to the group kermit: 
'pw groupmod kermit -m foo,bar,baz'

Roland
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