[PLUG] centos/rhel 7 ttyUSB group ownership with FTDI adapter

[Ben Koenig]

Even if you removed your custom rules, there might still be a default rule
that triggers for that device.
Maybe try searching through the config files in rules.d for the
vendor:product IDs of that particular adapter.

On Mon, Nov 26, 2018 at 2:32 PM Galen Seitz <galens at seitzassoc.com> wrote:

> Hi,
>
> When I connect a Prolific-based USB serial adapter to my CentOS 7
> machine, the corresponding ttyUSB device has dialout group ownership.
>
> [root at toto ~]# ls -l /dev/ttyUSB*
> crw-rw----. 1 root dialout 188, 0 Nov 26 14:15 /dev/ttyUSB0
>
> However, when I connect an FTDI-based serial adapter, the device has
> root group ownership.
>
> [root at toto ~]# ls -l /dev/ttyUSB*
> crw-rw----. 1 root dialout 188, 0 Nov 26 14:15 /dev/ttyUSB0
> crw-rw----+ 1 root root    188, 1 Nov 26 14:16 /dev/ttyUSB1
>
> Note the trailing '+' on the permissions.  It appears something is
> setting up an ACL, but only for the FTDI.
>
> [root at toto ~]# getfacl /dev/ttyUSB1
> getfacl: Removing leading '/' from absolute path names
> # file: dev/ttyUSB1
> # owner: root
> # group: root
> user::rw-
> user:galens:rw-
> group::rw-
> mask::rw-
> other::---
>
> The ACL suggests that I should have rw access, but kermit can't open the
> port.
>
> Note that I removed all of my custom udev rules and ran udevadm control
> --reload-rules before performing this test.
>
> I can sudo to workaround the problem, but I shouldn't have to.  Any
> ideas as to what is going on?
>
>
> thanks,
> galen
> --
> Galen Seitz
> galens at seitzassoc.com
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