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How to Send Mail from the Command Line with Telnet
You can easily test your mail configuration from a linux server with telnet.
$ telnet rhel1 25
Connected to rhel1.
Escape character is '^]'.
220 rhel1.localdomain ESMTP Postfix
HELO rhel1 # Note that "HELO" is not a misspelled. It is the command for telnet services.
MAIL FROM: ivan@rhel2
250 2.1.0 Ok
RCPT TO: david@rhel1
250 2.1.5 Ok
354 End data with <CR><LF>.<CR><LF>
Subject: Subject goes here.
Body goes here.
. # End body with '.' and Enter
250 2.0.0 Ok: queued as 5C3E5E12EA
# Quite interactive mail session with ctrl + ']'
221 2.0.0 Bye
Connection closed by foreign host.
For a more detail description, please see http://www.ehow.com/how_5209651_use-sendmail-command-line.html.
Server Comaparison between RHEL and Windows
An interesting comparison (in swedish) between RHEL server and Windows server.
How to Install KVM on Ubuntu 14.04 LTS (Trusty)
Verify that you have enabled virtualization in BIOS. For detail see Virtualization with KVM on RHEL 6
Install required packages.
Now you ready to run virt-manager and install new virtual guests.
If you are new to kvm, please read Virtualization with KVM on RHEL 6 for a detailed description.
Tweak Unity in Ubuntu 14.04
The preferred way to tweak the user interface (Unity) in Ubuntu 14.04 is via the unity-tweak-tool. You can also use ccsm - CompizConfig Settings Manager, but I would recommend to stick with the recommended unity-tweak-tool, since settings can be messed up, when manipulating settings with different tools.
And if you have got lost when configure, you can always get back to original configuration with:
Static Routes with RHEL 6
The new way to add static routes in RHEL 6 is
Or alternative via the old ip command style.
And to set the default gateway.
How to Install Minecraft in Ubuntu 14.04
Kids go crazy over the swedish developed game Minecraft. Below is a link how to install it on Ubuntu 14.04.
How to Merge Multiple PDF Files in Ubuntu
You can easily merge several pdf files into on file with 'pdftk - A handy tool for manipulating PDF'
Example how to merge file1.pdf and file2.pdf to mergedfile.pdf.
Convert MP4 to MP3 on Ubuntu 14.04 Trusty
There is a program available on Ubuntu youtube-dl, that can download videos from youtube.com or other video platforms. But it stores the file in mp4, since it contains video. But sometimes you do not want the video and only the audio. To extract only the audio part, you can use the pacpl comamnd line tool.
Bash Programming Documentation in RHEL 6
I'm not a bash script guru, so I need documentation. Here I will show you how to get/install that for RHEL 6.
All the BASH documentation is available via the bash-doc RPM, but it is not located in the RHEL base channel (rhel-x86_64-server-6), but in the RHEL Server Optional channel (rhel-x86_64-server-optional-6).
To add or remove channels from the command line you use the rhn-channel.
Now you are ready to install the bash-doc package.
And to list the installed files.
And the most interesting file is the BASH Reference Manual, as highlighted above.
Configure RHEL 6 as Router
In this blog I will show you how to configure a RHEL 6 server as router for LAN (eth1) and WAN (eth0).
Enable IP forwarding
First we need to enable IP forwarding.
And to verify.
To make it permanent, you need to edit /etc/sysctl.conf.
Configure Router Server Network
Before we begin, we disable NetworkManager.
Then we manually edit our network configuration files.
We begin with our WAN (eth0) card.
And continue with our LAN (eth1) card.
The above HWADDR is different for your environment. To get yours use ifconfig.
Finally restart network service and check new ip addresses are set, via ip or ifconfig command.
Now we are ready to configure iptables. First flush existing rules.
Then add the MASQUERADE roule to the WAN (eth0) card
Finally save iptables configuration.
I have connected a separate machine on LAN and configure it manually with static IP.
Now we can ping 192.168.2.100 (gateway), 192.168.1.100 (rhel 6 router), 192.168.1.1 (WAN GATEWAY) and finally www.google.com.
How To Install and Configure SAMBA Server on RHEL 6
The default configuration works just fine.
Having 'security = user' means we need a UNIX account. Lets create one.
And set samba password for account.
Now lets test it from a remote client. First lets list all shares on host.
And to mount it.
Finally lets test to write to winuser1 home directory.
This did not go well. The missing configuration is SELinux.
On the SAMBA server, run the following command, if you want to share home directories via samba.
Now lets get back to client and un mount and the remount and write and read and that should be successful.
Different Way to Mount NFS in RHEL6
The below will auto mount the user 'ldapuser1' home directory with rw permission on nfs.server.com.
You can manually mount a nfs exported directory to a local directory /remote.
Mount at boot
How to Install and Configure NFS Sharing on RHEL 6
To get nfs to work we need to install and start rpcbind and nfslock. Double check that is done.
Now we are ready to start NFS.
Finally lets test our new NFS server.
This will return a empty export list, without error.
To be able to access NFS exports remotely, we need to open certain ports in the firewall. To investigate which one, we use the command rpcinfo.
This will return quite some ports. To lock down which port that are used please uncomment all ports in NFS conf file.
Now restart NFS service and lets start open ports.
And after opening all ports the iptables should look like.
Test your new firewall configuration by from remote client execute command.
After we have successfully configured the firewall, lets back to our server and configure NFS export directories. We start with creating a new directory, that we will exports.
Now configure NFS to export it.
To apply the new changes run
And to list current exports
From a second machine on the same LAN, test connectivity to NFS server (192.168.1.15).
The simplest way to test read and write is to use the automounting functionality.
How to Install Chrome on Ubuntu 14.04 LTS (Trusty)
Open a Terminal and run the commands.
Add the public key for the Google repo.
Add the Google repo for the chome package.
Update and install chrome web browser.
How To Configure KVM Virtual Machine Network
Here I will configure a KVM host with virtual machines to be accessible from a local network.
This can be achieved in two ways by configure on KVM host machine:
- A network bridge
- Configure iptables as a router, which will forward traffic to virtual machines.
The easiest way is to use a network bridge, since then both desktop and virtual machines will be on the same subnet.
Here we will configure the KVM host machine network configuration, manually, so we start by disable the NetworkManager
KVM Host Network Bridge Configuration
Above we have disabled NetworkManager (NM_CONTROLLED=no) and is using a Bridge.
Above have we configured a static IP (BOOTPROTO=none) and assigned IP, Gateway and DNS.
KVM Host iptables
Since we are not using the second alternative with routing, the KVM host machines iptables configuration is the same as default.
After editing/creating files you might need to restore SELinux security contexts.
And finally restart network on KVM host
Virtual Macines Network Configuration
The last part is to configure the virtual machine network. This is easiest achieved with the virt-manager.
For an existing virtual machine.
And for a new.
Inside the Virtual Machine
Inside the virtual machine you can configure either a static IP or a dynamic one. The easiest way is to use the tool system-config-network-tui.
And finally test to ping the virtual machine (virtual1) from the desktop.
Fedora 20 Better Theme
The default theme (Adwaita) that Fedora 20 is shipped is not the best. And beside it has a large window border at the top of each window. A better theme that exists in default rpm repo is greybird. To install
and to change use gnome-tweak-tool (rpm package gnome-tweak-tool)
Fedora 20 Install MySQL Server 5.5 and Workbench 6
MySQL Server 5.5
The MySQL packages has been renamed. The now official open source version of MySQL is MariaDB. To install the same version of MySQL on Fedora as in Enterprise Linux, such as RHEL, install these packages.
To start the mysqld.
Set MySQL root password to 'root'.
Finally login and test password.
MySQL Workbench 6
The workbench rpm is orphan, so you need to download and install it manually. http://dev.mysql.com/downloads/tools/workbench/
Little bit of searching for installing dependeny packages, with 'yum provides', e.g.
And finally ending up with all required packages.
Then run install of workbench again and start workbench and connect to you localhost.
Fedora 20 How to Install Eclipse
Before Eclipse started with bundling Eclipse into EE, C++, etc bundles. There were pain to install Eclipse and to get all it's plugins right. Then the bundles came. You download a zip file and unzipped and off you go.
But a better way is to have RPM packages of everything. And that is done with Fedora. (That is also done in Ubuntu, but they don't have any modern version of Eclipse available.)
To install Eclipse 4.3.1 (Kepler)
Now you can search and install Eclipse plugin
Fedora 20 Disable Gnome Alt+Tab from Grouping Windows
Most modern Linux distros (and including Windows) now days group window from the same application. I found this not effective and lowers mine productivity.
To disable grouping when Alt-Tab switching, install gnome extension https://extensions.gnome.org/extension/15/alternatetab/
Install and Configure KVM on Fedora 20
To manage the KVM daemon - libvirtd.
- Data - /var/lib/libvirt/
- Configuration - /etc/libvirt/
Graphical manager, to install new virtual machines and control them.
Or the command line way.
And to control the virtual machines, via command line.
HTTP Configure LDAP-Based Authentication
In my previous blog I showed you how to set up basic authentication via access file for a private directory. To do the same thing for LDAP, use this configuration instead.
HTTP Configure Private Directories
Create Private Directory
Here we will make things a little more difficult, we are going to create our new directory outside the apache default document root, which means, we will need to manually handle SELinux policy. We will get into detail how to do that soon, but first lets create our new private directory.
Set file permissions.
Ok, here is where things get a little more complicated. Lets first have a look of the SELinux file context of the default document root.
Ok, now we knew how things should look like. Now lets look how things currently look in our new directory.
The thing you always should try first, is to try to restore default SELinux policy. Lets do that.
Ok, so the last part that is missing is the file context. We can set that with semanage (policycoreutils-python package).
And to verify.
Now we only need to restorecon on our new private directory.
Configure Private Directory
Now lets begin to add our new private directory as public and test.
Restart apache and test our new private directory. If things are not working go back and fix it.
Now we are going to add user authentication, but before that you might want to install apache manual.
We will here configure a basic authentication with file containing our user credential.
To create the user credential
And now finally restart and test your new private directory.
HTTP Deploy a Basic CGI Application
You have successfully installed apache web server with default configuration.
Copy our CGI script to default directory.
Set file permission
HTTP Configure a Virtual Host
Virtual hosts are good when you want to server multiple web sites from the same web server.
Install Apache Web Server.
Since I do not have a reliable DNS, we need to hardcode the host name in /etc/hosts on the client.
Configure Listen and ServerName, to be able to start the server clean without warnings.
Also verify that firewall (iptables) is configured or stop it 'service iptables stop'.
Now check our installation by restarting apache web server and open url 'jbossas1.magnuskkarlsson.com' from client machine. You should be able to see Apache Welcome Page. If not go back and fix.
Configure Name-Based Virtual Hosting
Now create two virtual host, one for the default host 'jbossas1.magnuskkarlsson.com' and one new 'virtualhost1.magnuskkarlsson.com'.
Now create the new document root for 'virtualhost1.magnuskkarlsson.com'.
Set file permissions.
Create test web page.
Set SELinux for our new virtual host.
Restart apache web server and test your new virtual host by accessing:
- http://virtualhost1.magnuskkarlsson.com/ (you should see default apache web server welcome page)
- http://jbossas1.magnuskkarlsson.com/ (you should see your 'Hello World' page)
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