sudo not available after configuring ipmi serial over lan

[Ian Lepore]

On Thu, 2018-11-08 at 12:47 -0500, Jordan Caraballo wrote:
> Hi Ian,
> Changing the line following line from std.115200 to 3wire.115200
> worked.
> Can you explain the why? I am not entirely sure of the difference
> between
> 3wire and std there.
> 
> ttyu0   "/usr/libexec/getty 3wire.115200" vt100   on          secure
> 
> Thanks,
> - Jordan
> 

The standard setting honors the modem control lines on the serial port,
so any attempt to open that serial device will block until the carrier-
detect line on the port is asserted.

The 3wire setting indicates that only RX, TX, and GND are connected,
and modem-control signals should be ignored. An open of such a device
will return immediately whether anything is actually connected to the
serial port or not.

A /dev/ttyN device is assumed to be a "call-in" device and has the
blocking behavior by default. A /dev/cuaN device is assumed to be a
"call-out" device that doesn't wait for modem carrier by blocking.
Using the std vs 3wire designations in /etc/ttys causes init(1) to set
termios(4) flags to implement blocking-open or immediate-open behavior
without needing to change the device name as well.

-- Ian

> El jue., 8 nov. 2018 a las 10:39, Ian Lepore (<ian at freebsd.org>)
> escribió:
> 
> > 
> > On Thu, 2018-11-08 at 06:10 +0700, Eugene Grosbein wrote:
> > > 
> > > 08.11.2018 5:56, Jordan Caraballo wrote:
> > > 
> > > > 
> > > > 
> > > > Hi guys,
> > > > 
> > > > After configuring ipmi serial over lan console, I am not being
> > > > able
> > > > to
> > > > execute any command related to sudo; not even "sudo su -". I am
> > > > using ttyu0
> > > > and COM1 on a Dell R530. Everything regarding receiving output
> > > > and
> > > > typing
> > > > at the serial console is fine; the only command not working is
> > > > sudo.
> > > > 
> > > > Any ideas? Below are the configurations.
> > > > 
> > > > /etc/ttys
> > > > 
> > > > # Serial terminals
> > > > # The 'dialup' keyword identifies dialin lines to login,
> > > > fingerd
> > > > etc.
> > > > #ttyu0  "/usr/libexec/getty 3wire"      vt100   onifconsole
> > > > secure
> > > > ttyu0   "/usr/libexec/getty std.115200"
> > > > vt100   on          secure
> > > Use network access to perform the following:
> > > 
> > > 1) Change "on" to "off" for ttyu0 then run "init q" to apply
> > > changes.
> > > 2) Replace "ttyu0" with "cuau0" within same line then run "init
> > > q"
> > > again.
> > > 
> > > Then retry using console and sudo.
> > The easy way to accomplish the same thing is to change std.115200
> > to
> > 3wire.115200 (and then do 'init q').
> > 
> > -- Ian
> > 
>