DevHeads.net

Postings by isdtor

Meltdown and Spectre

Does anyone know if Red Hat are working on backporting improved mitigation techniques and features from newer, 4.14.14+ kernels?

$ grep . /sys/devices/system/cpu/vulnerabilities/*
/sys/devices/system/cpu/vulnerabilities/meltdown:Mitigation: PTI
/sys/devices/system/cpu/vulnerabilities/spectre_v1:Vulnerable
/sys/devices/system/cpu/vulnerabilities/spectre_v2:Vulnerable: Minimal generic ASM retpoline
$

dbus-daemon and CentOS6

We are seeing high load developing over time on some machines that have dozens of user sessions. One common characteristic is that dbus-daemon uses near 100% cpu.

Red Hat seems to be aware of the problem, but the solutions are available to subscribers only.

<a href="https://access.redhat.com/solutions/110403" title="https://access.redhat.com/solutions/110403">https://access.redhat.com/solutions/110403</a>
<a href="https://access.redhat.com/solutions/363554" title="https://access.redhat.com/solutions/363554">https://access.redhat.com/solutions/363554</a>

Does anyone have access and can summarize here?

Thanks.

Flash player beta

Has anyone tried the new flash player beta for Linux?

<a href="http://labs.adobe.com/downloads/flashplayer.html" title="http://labs.adobe.com/downloads/flashplayer.html">http://labs.adobe.com/downloads/flashplayer.html</a>

I can't get it to work on CentOS 6.8, ff 45.3.0-1, all x86_64.

CentOS 6.8 and samba

Other than the original 6.8 release version 3.6.23-33, samba has not been functioning correctly for me under 6.8.

The symptoms are that about 6-7 days after starting the server, users start complaining that they can no longer open documents on their share. Upon inspection, I find several, sometimes nearly a dozen smb
processes owned by a single user, on top of those run under root. Stopping the service does not stop these processes. They are only killable with SIGKILL, and after that, a service restart does not result
in a functioning service, i.e.

Gnome weather applet stranded

The Gnome weather report applet has ceased working on CentOS5/6. <a href="http://weather.noaa.gov/" title="http://weather.noaa.gov/">http://weather.noaa.gov/</a> says "This service is no longer available". Are there any good alternatives? I liked the applet as it allowed the use of a custom radar map.

As I just discovered, the weather functionality of the CentOS6 Gnome clock applet was using the same service.

CenOS 6.8 and libGL failures

Ever since I upgraded to CentOS 6.8, some software has stopped working alogether.

Kickstarting bonded interfaces

Since CentOS 6.4, anaconda supports kickstarting from bonded interfaces. Has anyone managed to get this working?

Bonding modes 1, 5, 6 work fine, and they do not need any particular support on the switch.

x2go on CentOS6

Has anyone managed to get the x2go server working on CentOS 6.7?

I started testing x2go from EPEL under 6.6, and it worked well. Then I didn't use it in 6 months plus, eventually upgraded the machine to 6.7, and it's no longer working. Both Windows and Linux clients error out with "Connection failed.

groupadd failure

The munin rpms from EPEL failed to install correctly on a particular
machine. This is why

# /usr/sbin/groupadd -r munin
groupadd: Can't get unique system GID (no more available GIDs)
#

but I don't understand why this happens. Even after checking the man pages
for groupadd and login.defs, I have been unable to determine what the
settings for SYS_GID_MIN/SYS_GID_MAX on RHEL/CentOS are. None of the 5/6
machines I have access to list them in login.defs. Even assuming
relatively conservative values of 201/499, resp.

Migrating to IdM

I have just started looking through the RHEL6 IdM guide, and while the documentation seems quite thorough and extensive, the examples are somewhat on the weak side. Migration scenarios can be much more complex - e.g. migrating away from NIS while at the same time moving to LDAP or AD for user account management.

PXE question

I was wondering, where is the format and options of files like
/usr/share/system-config-netboot/pxelinux.cfg/default from
system-config-netboot-cmd described? There are plenty of PXE tutorials
with examples out there, but nothing that looks like actual
documentation.

CentOS6 gvfs disk thrashing

We recently started upgrading users' workstations to CentOS6. Now
we've come across an interesting issue:
~user/.local/share/gvfs-metadata is filling up with tons of files.
Once there are around 69270 of them, no more are being created, and
the NetApp filer the user's home is on logs:

Directory ..../user/.local/share/gvfs-metadata/ reached the maxdirsize
limit. Reduce the number of files or use the vol options command to
increase this limit..

Nearly all of the files are exactly 32k in size and they are named
.openXXXXXX.

3rd party repositories

Can anyone comment on the use of 3rd party repos for newer versions of
software like php, python and mysql? Two I am aware of are puias and ius.

Is one preferable to the other? Can their packages be installed in parallel
to and without interfering with base packages?

Merging os and updates

I've been able to successfully kickstart CentOS 3.9 from the base
repo, but no such luck after merging os and updates. I think I did
everything right - updated base/comps.xml and regenerated
hdlist/hdlist2. Updated the yum repo as well although I'm pretty sure
it's not used by anaconda.

This is difficult to debug. The setup is running under kvm on a CentOS
6.4 host, and for some reason, a completely headless install fails
(--graphics none; virt-viewer complains loudly and dies).

Network interface status

Under CentOS6, is it possible to get an interface to RUNNING state
without assigning a (dummy) IP address?

# ifconfig em2
em2 Link encap:Ethernet HWaddr 78:2B:CB:67:3E:5C
UP BROADCAST MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)

This was working fine on RHEL3 simply by running ifconfig up.

# ifconfig eth1 up
# ifconfig eth1
eth1 Link encap:Ethernet HWaddr 00:11:25:57:8B:2D

CentOS6 and tilde expansion

Set up NIS and autofs on this new CentOS6 box, but it seems tilde
expansion no longer works in bash?

[root@frodo ~]# cd ~john
-bash: cd: ~john: No such file or directory
[root@frodo ~]# cd /home/john
[root@frodo john]# pwd
/home/john
[root@frodo john]#

It still works in t/csh:

[root@frodo ~]# /bin/csh
[root@frodo ~]# cd ~john
[root@frodo ~john]# pwd
/home/john
[root@frodo ~john]#

I couldn't find anything in the bash man page that suggests this
feature needs explicit configuration.