dusko + rhel   40

RHEL7 - How to get started with package groups
The package groups are a well-known feature of the yum command to group multiple packages under a single name.

Even though yum will be replaced with dnf in future releases of RHEL, the syntax and features will stay the same (at least this is the case in Fedora 22 where you can replace yum with dnf without any problem).

Three kinds of package groups exist:

environment package groups describe a type of global configuration containing other package groups: Minimal Install, Compute Node, Infrastructure Server, GNOME Desktop, etc.
top-level package groups bring a set of package groups belonging to the same domain: Security Tools, Development Tools, System Administration Tools, etc.
simple package groups contain packages on a particular topic: web-server, network-file-system-client, etc.

Also, inside a package group, there are potentially three different categories:

mandatory package groups/packages are always installed.
default package groups/packages are normally installed except if specified otherwise.
optional package groups/packages are only installed on demand.

Note: While some yum subcommands groupinfo, grouplist and groupinstall were written with only one word in RHEL 6, RHEL 7 now accepts one or two words: yum groupinfo/yum group info, yum grouplist/yum group list, yum groupinstall/yum group install, etc.
linux  rhel  centos  automation  devops  sysadmin 
12 days ago by dusko
How to list an installation gropinstall collections on Redhat Linux - LinuxConfig.org
How to list an installation gropinstall package collections on Redhat Linux

Installation grouplist is a ready to install collection of software packages and its dependencies to fit a given purpose. To list common groupinstall collection we can run yum grouplist command:
linux  rhel  centos  automation  devops  sysadmin 
12 days ago by dusko
Sample kickstart configuration file for RHEL 7 / CentOS 7
Sample kickstart configuration file for RHEL 7 / CentOS 7
linux  rhel  centos  automation  devops  sysadmin 
12 days ago by dusko
RPM Search
Useful for finding old/deprecated packages for not-supported Linux distributions, e.g. Mandrake.
linux  rhel 
november 2017 by dusko
HowTos/RsnapshotBackups - CentOS Wiki
This guide will assist you in setting up an rsnapshot backup server on your network. It will briefly explain setting up passwordless logins via SSH for rsync using SSH keys. For quite some time, I was using the utility Synbak (http://www.initzero.it/portal/soluzioni/software-open-source/synbak-universal-backup-system_2623.html) to automate backing up my laptop at home to my desktop. Before that, a simple rsync script was doing the task. Although Synbak is a wonderful utility for simplifying backups at home, it's not quite as flexible as rsnapshot. (Synbak's power lies in it's ease of installation and use.) This guide assumes using RPM packages extending the author's documentation for specifics on installation using CentOS/Fedora.
linux  rhel  centos  rsync  rsnapshot  backup 
september 2017 by dusko
Software Collections - All versions of any software on your system. Together.
All versions of any software on your system. Together.

Software Collections give you the power to build, install, and use
multiple versions of software on the same system, without
affecting system-wide installed packages.

Looking for a new release of Ruby, Python, Perl, or want to install Node.js on your Enterprise Linux? How about an alternative to MySQL, MariaDB 10.1, or PostgreSQL 9.5? You can find the components you need in the SoftwareCollections.org Directory.
linux  rhel  centos  sysadmin 
august 2017 by dusko
IUS - IUS Community Project -- Inline with Upstream Stable
IUS is a community project that provides RPM packages for newer versions of select software for Enterprise Linux distributions.

Project Goals:
- Create high quality RPM packages for Red Hat Enterprise Linux (RHEL) and CentOS.
- Promptly release updated RPM packages once new versions are released by the upstream developers.
- No automatic replacement of stock RPM packages.
rhel  linux  centos  packagemanagement  sysadmin 
august 2017 by dusko
Check if remote host/port is open - Can't use GNU Netcat nor NMap - RHEL 7
Bash allows you to connect to TCP and/or UDP ports by redirecting to special files:

/dev/tcp/host/port If host is a valid hostname or Internet address, and port is an integer port number or service name, Bash attempts to open the corresponding TCP socket.

/dev/udp/host/port If host is a valid hostname or Internet address, and port is an integer port number or service name, Bash attempts to open the corresponding UDP socket.

A failure to open or create a file causes the redirection to fail.

So to test if you can connect to port 80 on www.example.com the following should work:

echo -n > /dev/tcp/www.example.com/80

If the port is blocked you either get a "connection refused" message or a timeout.
linux  rhel  centos  cli  networking 
july 2017 by dusko
Commands not found: netstat, nmap on CentOS 7 - unix.stackexchange.com
Also, excerpt from ug 1119297 - Add net-tools to @core group ( https://bugzilla.redhat.com/show_bug.cgi?id=1119297 ):

As stated before, net-tools are deprecated thus shouldn't be used unless necessary. Behaviour in RHEL 7 is the same as in Fedora - net-tools is missing from minimal install, but is in @base (~= @standard in Fedora) which is installed in all non-minimal configurations.

There are also other tickets that deal with this such as IDs 682308 - Bug 682308 - [RFE]: move away of net-tools to iproute (https://bugzilla.redhat.com/show_bug.cgi?id=682308) and 687920 - Bug 687920 - [net-tools DEPRECATED] these packages still depend on it (https://bugzilla.redhat.com/show_bug.cgi?id=687920). Note that they are assigned to the Fedora project and are quite old
linux  networking  rhel  centos 
july 2017 by dusko
The comps file - Burning a RedHat CD HOWTO
The comps file defines how the packages are bundled during the installation. In the Red Hat distribution, this is done according to the functionality they provide, for example:

1.) Printer Support
2.) X Window System
3.) GNOME
4.) KDE
5.) Mail/WWW/News Tools
6.) ...
7.) Kernel Development
8.) Extra Documentation

Sometime during the installation process, the user is presented with a dialog called "Components to install".

Some of the components have been preselected, and others not. The last item on the components list is called "Everything". On the dialog box, there is also an option that enables the user to customize exactly what packages will be installed.

Customizing the installation by hand, or selecting "Everything" in the components list is the only way to have your own packages installed **unless** you modify the RedHat/base/comps file.
linux  rhel  centos 
july 2017 by dusko
nc (netcat) and any reason why redhat chooses to install this by default?
Even a minimal install seems to grab this package so I checked
comps.xml
and there it was under the core group as a default install.

netcat is a great tool for troubleshooting but not something I would want to leave on the system (I remove it) but I cannot seem to understand **why** such a potentially dangerous tool is installed by default.

Although this is not "RedHat", the CentOS group mirrors "RedHat" as much as possible and I see the same installation behavior. So I was curious if anyone knew why? rpm -e nc shows no dependencies to the package. Removing it seems to do no harm to the system either.
linux  rhel  centos  sysadmin 
july 2017 by dusko
Samba Configuration Tool - Samba Configuration Helper
Posted: Jan 19, 2015 -- One comment: Nice for a simple configuration. Ideally you would have something that help through complex configurations that enterprise customers use and would have an option to generate differing SAMBA configurations between SAMBA 3.5 (6.4) and SAMBA 3.6.9 (6.5).
sysadmin  rhel  linux 
january 2015 by dusko
Setting up SFTP-only Users on RHEL/CentOS 5
Setting up SFTP-only Users on RHEL/CentOS 5
sysadmin  CentOS  linux  rhel 
december 2014 by dusko

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