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teggenberger 10-24-2019 10:35 AM

Ubuntu Serial Port usage
I have a desktop PC running Ubuntu 18.4. The PC has a DB-9 Serial port on the back and i'm trying to connect direct to a piece of hardware console port.

The Port is recognized on Ubuntu as:

teggenbe@teggenbe:~$ dmesg | grep tty
[ 0.000000] console [tty0] enabled
[ 0.801726] 00:02: ttyS0 at I/O 0x3f8 (irq = 4, base_baud = 115200) is a 16550A

However, when i try to connect using SercureCRT i see this:

Unable to open serial port /dev/ttyS0:
  Permission denied

I've tried different speeds and 'flow control' but always get the same message.
Is there a setting somewhere i'm missing?
I even tried to add 'sudo' in the pre-connect properties option.


berdmann 10-24-2019 03:24 PM

Hi teggenberger,

SecureCRT makes a call to the system to open the serial port when a serial connection is made. So it is likely that the behavior is a result of a configuration issue on the machine. This theory is also supported by the "Permission denied" error that you are seeing. SecureCRT is not allowed to prohibit or grant access to operating system level functions.

Is your user account a member of the dialout group listed for your console cable?

We had a customer report similiar behavior in the past and he provided the following steps:

1. Confirm that /dev/ttyS0 is member of the dialout group using:

        ls -l /dev/ttyS0
2. Make your user account a member of the dialout group using:

        sudo adduser <username> dialout
3. Reboot using:

        sudo reboot

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