Can't access console/local command prompt

elliot01 · 09-29-2013, 11:49 AM

Hi all,

I have a RHEL6 server sitting in a data centre. We hardly ever have cause to access the local console, but we can do remotely using a KVM in the same rack.

I have been doing some maintenance remotely and have noticed that once RHEL6 has booted, a console is not presented locally.

All other services startup fine (that we know of). This is a production server running multiple critical services to a mid-size company.

I have reason to make some changes with the network config and don't want to while I have to no access to the local console via the KVM (I can remotely connect to the KVM, then operate the server as though I was local).

It's impossible to know when this problem manifested because, as mentioned, we typically don't use the local console.

One tip I read was to ensure there is a "console" entry in my /etc/securetty file. it's already there.

Is there any common cause for this which anyone can suggest looking into first?

Thanks in advance.

Elliot

kbp · 10-05-2013, 06:56 AM

Maybe check the kernel boot arguments to make sure the console hasn't been redirected to a serial port or similar ?

elliot01 · 10-07-2013, 01:13 PM

Hi kbp,

Thank you for the reply, I will follow up on this and take a look.

trey85stang · 10-07-2013, 01:44 PM

the default consoles (the ones accessed on cntrl alt F1/F2 etc) are generally launched via inittab. Default centos6 should have these entries:

# Run gettys in standard runlevels
1:2345:respawn:/sbin/mingetty tty1
2:2345:respawn:/sbin/mingetty tty2
3:2345:respawn:/sbin/mingetty tty3
4:2345:respawn:/sbin/mingetty tty4
5:2345:respawn:/sbin/mingetty tty5
6:2345:respawn:/sbin/mingetty tty6

if you dont have those then tty's will just be blank. I've worked at a few companies that want those disabled except for in init1.

elliot01 · 10-09-2013, 09:12 AM

Hi guys,

These are my active kernel parameters:

"
kernel /boot/vmlinuz-2.6.32-358.18.1.el6.x86_64 ro root=UUID=0af825b9-7016-4de1-a967-1c315ef72826 rd_NO_LUKS rd_NO_LVM rd_NO_MD rd_NO_DM LANG=en_US.UTF-8 SYSFONT=latarcyrheb-sun16 KEYBOARDTYPE=pc KEYTABLE=uk crashkernel=auto intremap=off
"

A quickl Google reference doesn't seem to indicate the problem lies here - but confirmation would be appreciated

Checking inittab next.

elliot01 · 10-09-2013, 09:52 AM

The server I am working on is RHEL6 and the inittab is as follows. As far as I'm aware this hasn't been changed since installation. Does this look right - I'm not familiar with changing this file:

Code:

# inittab is only used by upstart for the default runlevel.
#
# ADDING OTHER CONFIGURATION HERE WILL HAVE NO EFFECT ON YOUR SYSTEM.
#
# System initialization is started by /etc/init/rcS.conf
#
# Individual runlevels are started by /etc/init/rc.conf
#
# Ctrl-Alt-Delete is handled by /etc/init/control-alt-delete.conf
#
# Terminal gettys are handled by /etc/init/tty.conf and /etc/init/serial.conf,
# with configuration in /etc/sysconfig/init.
#
# For information on how to write upstart event handlers, or how
# upstart works, see init(5), init(8), and initctl(8).
#
# Default runlevel. The runlevels used are:
#   0 - halt (Do NOT set initdefault to this)
#   1 - Single user mode
#   2 - Multiuser, without NFS (The same as 3, if you do not have networking)
#   3 - Full multiuser mode
#   4 - unused
#   5 - X11
#   6 - reboot (Do NOT set initdefault to this)
#
id:3:initdefault:

Thanks

elliot01 · 10-09-2013, 09:57 AM

I'm just comparing the inittab and going through the referenced files, against a CentOS 6 server I have in the same rack, which displays the console login fine. So far these files are looking identical.

elliot01 · 10-09-2013, 10:11 AM

I'm not sure I have been clear on something. When I reboot the server and remotely connect to the console session via the KVM, I can actually see the bootup process and watch all the services startup etc, but it's when the server appears to have fully started up I would expect to be given the local login prompt - at this stage, nothing happens. I'm not sure how else to explain it, but this is probably down to my lack of familiarity with linux.

Here's a screenshot of the local console, 17.5 hours after bootup. Where my login prompt!?

kbp · 10-09-2013, 04:09 PM

What happens if you press [enter] ?

elliot01 · 10-16-2013, 06:34 AM

The screen scrolls up a line if I press enter, appearing to prove that keyboard input is passed through the KVM to the Red Hat console without a problem.

If I enter CTRL-C, q, enter, enter, enter.. etc no command prompt appears.

I can key in random text which appears on the console screen, but there's no shell/interpreter so nothing happens.

kbp · 10-16-2013, 07:44 AM

This DBfax scheduler init script seems to be not exiting cleanly, just staying active. If you log in via ssh and disable this service does the console come up ok on reboot?