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Postings by Niki Kovacs

Apache and web content permissions

Hi,

Until a few months ago, when I had to setup a web server under CentOS, I
assigned (I'm not sure about the correct english verb for "chown"ing)
all the web pages to the apache user and group. To give you an example,
let's say I have a static website under /var/www/myserver on a CentOS
server running Apache.

CentOS 7 + NVidia Quadro 2000 graphic card

Hi,

I'm currently trying to install CentOS 7 (desktop) on a Lenovo
workstation with an NVidia Quadro 2000 graphical card.

Normally I know my way around NVidia cards and how to configure them
either using the ELRepo drivers or those downloaded from nvidia.com. I
have written a corresponding article on my blog:

<a href="https://blog.microlinux.fr/nvidia-centos/" title="https://blog.microlinux.fr/nvidia-centos/">https://blog.microlinux.fr/nvidia-centos/</a>

But this time it looks like I have no luck. ELRepo's nvidia-detect
utility detected the 'kmod-nvidia' driver, but installing it gave no
result.

Configure an Out Of Office Reply with Postfix?

Hi,

I'm running a Postfix mail server on CentOS 7 for our local school. Some
users would like to have an out of office reply for the holiday season.
I see there is a little utility called 'vacation', and I wonder if this
is the right tool for the job.

Any recommendations?

Niki

Transferring Thunderbird mail accounts: Windows vs. Linux

Hi,

One of my clients brought me his PC with Windows 7, so I can migrate it
to Linux, e. g. CentOS 7 + KDE. So far I made a backup of all the data,
but I wonder how I can migrate the existing Thunderbird account.

An operation I perform quite regularly is replace an existing Linux
system (Ubuntu, openSUSE, Fedora, whatever) by CentOS. When Thunderbird
is configured, I just backup the whole ~/.thunderbird directory and then
restore it on the new installation, which usually works perfectly. Any
idea if I do this when moving a desktop installation from Windows 7 to
CentOS?

Cheers,

Niki

Firefox Sync Server 1.5 on CentOS 7

Hi,

I'm currently experimenting with setting up my own Firefox Sync Server
on a public server running CentOS 7, following this document:

<a href="https://mozilla-services.readthedocs.io/en/latest/howtos/run-sync-1.5.html" title="https://mozilla-services.readthedocs.io/en/latest/howtos/run-sync-1.5.html">https://mozilla-services.readthedocs.io/en/latest/howtos/run-sync-1.5.html</a>

So far I have a partial success. Bookmarks are syncing via the basic
internal server running on port 5000, and I can also configure a MySQL
database for bookmark storage.

Accidentally removed sync system user

Hi,

As the subject says, I accidentally removed the 'sync' system user.

CentOS 7 not shutting down correctly

Hi,

I have CentOS 7 with KDE installed on my workstation. Sometimes - like
just now - the system refuses to shutdown correctly. The problem
appeared since I installed the OpenVAS vulnerability scanner (the one
from EPEL), so I don't know if this is linked.

New CentOS/RHEL group on Facebook

Hi,

There are currently two competing CentOS groups on Facebook. The "main"
group is managed by a small group of autocrats with very unilateral
communication skills.

SpamAssassin vs. SELinux

Hi,

I just installed SpamAssassin on two servers running CentOS 7 and
Postfix. One is my sandbox server for experimenting, the other one is
the server that hosts my company's web site, blog, mail, etc.

So far, SpamAssassin seems to work as expected.

Strange problem with CentOS 7 and guest additions in VirtualBox

Hi,

I'm having a very weird problem with CentOS as a VirtualBox guest. Let
me explain it step by step.

tl;dr: I can install VirtualBox Guest Additions and configure a
fullscreen 1280x1024 graphical resolution on a full install, but not on
a reduced install with a lightweight window manager.

Here's what I did.

1. Install vanilla CentOS 7 with KDE.

2. Boot to reduced 1024x768 resolution.

3. Install gcc, make and kernel-devel.

4. Build VirtualBox Guest Additions.

5. Reboot to full 1280x1024 resolution. ==> perfect

On a vanilla desktop installation, this works perfectly.

yum groupinstall vs. yum group install

Hi,

Is there a difference between 'yum groupinstall' and 'yum group
install'? As far as I can tell,

# yum groupinstall "X Window System"

and

# yum group install "X Window System"

get me the same result.

Just curious.

Niki

Use CentOS to create a bootable Mac OS X DVD from dmg file?

Hi,

Sorry if this is only half-CentOS-related.

In my office, I'm running CentOS on all my systems (server, workstation,
laptop, sandbox PCs). A colleague brought me her MacBook Pro to upgrade
it from OS X 10.5.7 to 10.11.6.

I downloaded the 5.8 GB dmg file and now I wonder how to create a
bootable DVD with this using only Linux tools.

1. Can I simply burn this as a data DVD with K3B?

2.

CentOS 7: changes to php.ini

Hi,

I'm hosting a few web apps like OwnCloud, Wordpress and Dolibarr on
CentOS 7 that require a handful of changes to php.ini. I have to define
some custom values for post_max_size, upload_max_filesize, etc.

I don't know if I'm supposed to edit /etc/php.ini directly or if changes
should be put in a configuration file stub in /etc/php.d.

CentOS, PHP & OwnCloud/Nextcloud: the version dilemma

Hi,

I'm currently experimenting with OwnCloud and Nextcloud on a sandbox
CentOS 7 server. I've been using OwnCloud for the last two years for my
own purposes on a Slackware server, and I'm quite happy with it.

In my humble opinion, every admin who wants to host OwnCloud or
Nextcloud on a RHEL/CentOS server is confronted with a version dilemma.

1. CentOS 7 sports PHP 5.4, which has been officially EOL for quite some
time, but Red Hat will provide security update backports until 2024.
Which is fine.

2.

Block internet access for some users on the LAN ?

Hi,

In our local school we have two servers and roughly 80 clients.

systemctl poweroff

Hi,

I've been using CentOS since versions 4.x, and I see a weird trend in
recent Linux distributions.

Under CentOS 4.x, 5.x and 6.x, shutting down a server (workstation,
laptop) simply meant issuing 'shutdown -h now' (or choosing 'Shutdown'
from the GUI menu), and the machine would simply shut down.

Flush memory on a server?

Hi,

A few days ago I checked the health of my main public server running
CentOS 7, a quad-core machine with 16 GB RAM. It had been running
non-stop for 65 days, hosting only a handful of services (BIND, NTP,
Apache, Postfix, Dovecot) for two domains.

I was surprised to see that RAM consumption was relatively high, and
apparently, the machine even had to swap at some time.

I read up a bit on RAM consumption, and now I wonder if flushing the
memory cache regularly is a good idea.

<a href="https://tecadmin.net/flush-memory-cache-on-linux-server/" title="https://tecadmin.net/flush-memory-cache-on-linux-server/">https://tecadmin.net/flush-memory-cache-on-linux-server/</a>

Any suggestions?

Niki

TeX Live on CentOS 7

Hi,

I just installed the OpenVAS vulnerability scanner on my CentOS 7
workstation. Everything seems to work fine, except PDF generation. The
'openvas-check-setup' script tells me that PDF generation works fine,
but whenever I want to generate a report, the result is unusable and
can't open in Evince or Okular.

After googling a bit, I found out that several users complained that Tex
Live is broken under RHEL/CentOS 7.

While I did use LaTeX a long time ago to write documents, I don't use it
anymore nowadays (just Markdown or LibreOffice).

Ark can't handle RAR archive

Hi,

I'm running CentOS 7 with KDE. Ark can't seem to handle a RAR archive,
even though I have unrar from the Nux repository installed.

Any idea what's wrong here?

Cheers,

Niki

OpenVAS: confusion with 3rd party repos

Hi,

I'm currently experimenting with OpenVAS, the vulnerability scanner
which was forked from Nessus.

I'm reading through various HOWTOs and tutorials, and it seems like I'm
stuck very early in my fiddling process.

All the CentOS-based tutorials I've found mention a third-party Atomic
repo, and here's how the installation usually begins.

# wget -q -O - <a href="http://www.atomicorp.com/installers/atomic" title="http://www.atomicorp.com/installers/atomic">http://www.atomicorp.com/installers/atomic</a> | sh

Yet on my servers I have EPEL configured for my third-party needs, and
OpenVAS already seems available through EPEL.

# yum search openvas
...
openvas-cli.x86_64
openvas-gsa.x86_64
openvas-l

Getting started with mod_security

Hi,

I'm currently fiddling with mod_security, and before going any further,
I simply wanted to ask here for any recommended documentation/tutorials
on the subject. There seems to be a lot of information about
mod_security out there, and right now I have a bit of a hard time
wrapping my head around it.

I'm grateful for any suggestions.

Cheers,

Niki Kovacs

CentOS 7 + KDE: sleep mode?

Hi,

One of my clients is running CentOS 7 + KDE 4.14 which I installed for
her. Everything is running nicely. She asked me - more out of curiosity
- if she could use the "Sleep" mode instead of "Shutdown" like she did
when she ran Windows, so the PC would be up and running faster the next
time. I didn't know what to answer, since I don't explicitly use this
mode. Only on my laptop I simple shut the lid, which puts the laptop
into Sleep mode. But on a normal PC, I don't know if this mode is
supposed to be used.

Any suggestions?

Niki

Hardening Apache on CentOS 7

Hi,

Some time ago one of my public servers (running Slackware64 14.0) got
attacked and was misused to send phishing emails.

This misadventure made me more concerned about security, so I spent the
last few weeks catching up on security, reading docs about SELinux and
how to use it, etc.

I have a public sandbox server running CentOS 7, and I'm currently
experimenting quite a lot with Apache and how to secure it. My approach
is very much trial-and-error.

Apache + mod_evasive : problem with test.pl

Hi,

I'm currently experimenting with the mod_evasive module for Apache, to
protect the server against potential DoS attacks. Here's what I did so far.

# yum install mod_evasive

Don't touch mod_evasive's default configuration, just restart Apache.

# systemctl restart httpd

The package includes a test.pl script supposed to launch a testing DoS
attack.

Web server files ownership?

Hi,

I have a series of websites hosted on two CentOS 7 servers, using Apache
virtual hosts. One of these servers is a "sandbox" machine, to test
things and to fiddle around.

On the sandbox server, I have a few dummy websites I'm hosting.

# ls /var/www/html/
default phpinfo slackbox-mail slackbox-site unixbox-mail unixbox-site

Since Apache is running as system user 'apache' and system group
'apache', I thought it sensible that hosted files be owned by that process.

# ls -l /var/www/html/
total 24
drwxr-x---. 3 apache apache 4096 6 juil. 09:37 default
drwxr-x---.

Problem with ipa-client

Hi,

Here's the warning that Yum currently displays:

** Found 3 pre-existing rpmdb problem(s), 'yum check' output follows:
ipa-client-4.4.0-14.el7.centos.7.x86_64 has installed conflicts
freeipa-client: ipa-client-4.4.0-14.el7.centos.7.x86_64
ipa-client-common-4.4.0-14.el7.centos.7.noarch has installed conflicts
freeipa-client-common: ipa-client-common-4.4.0-14.el7.centos.7.noarch
ipa-common-4.4.0-14.el7.centos.7.noarch has installed conflicts
freeipa-common: ipa-common-4.4.0-14.el7.centos.7.noarch

Any suggestions what I can do about that? (BTW, I don't use IPA)

Cheers,

Niki

Physically moving a mail server vs. cached DNS

Hi,

I just moved my main mail account and web content from a low-cost
(low-quality) provider to my own root server running CentOS 7. I
transferred the domain name from DNS management to my registrar,
configured BIND, Apache, Postfix, Dovecot, NTP, SELinux, etc. Now things
are running rather nicely.

Markdown editor for CentOS 7?

Hi,

I recently discovered Markdown, and I'm currently using it to write some
documentation for CentOS 7.

<a href="https://github.com/kikinovak/formation-linux" title="https://github.com/kikinovak/formation-linux">https://github.com/kikinovak/formation-linux</a>

For the time being, I'm using my good old Vim editor for writing it. I
turned off syntax highlighting, since this produces random results with
Markdown.

Pages are correctly displayed on Github, but in order to see them, I
have to push them to the server. Now I wonder if there's a good WYSIWYG
editor for Markdown, or at least something where I can check locally
what the page looks like.

Any suggestions?

Niki Kovacs

CentOS 7 + KDE: Okular view PDF files OK but prints a blank page

Hi,

I recently installed CentOS 7 + KDE 4.14 on my main workstation, and
overall I'm very happy with it.

Okular seems to have trouble with some PDF files. I'm using the Dolibarr
application to generate invoices. I can view the resulting PDF file OK,
but when I try to print it, I get a blank page. A few days ago I had a
similar problem with a PDF file generated from a french administration
online form.

On my previous installation (Slackware64 14.1 + Xfce + Evince built from
source) I never had any trouble with PDF files.

Any suggestions?

Cheers,

Niki Kovacs

Virt-Manager and full-screen display

Hi,

I have CentOS 7 with Qemu/KVM and Libvirt running on a headless HP
Proliant Server. Virtual hosts are managed via Virt-Manager installed on
a CentOS 7 + KDE client via SSH.

Things are running quite nicely for now, I only have a few small minor
details to adjust.

On my main workstation running Slackware64 14.1, I also have Qemu/KVM
and Virt-Manager installed. When I launch a virtual host and switch to
full-screen display, the host is a "real" full screen.

But when I do the same thing with CentOS, I don't have a real
full-screen display.