GNU/Linux

Device has MAC address X, instead of configured address Y.

18 February 2017 in GNU/Linux tagged address / eth0 / MAC by Tux

Recently, we tried to take a network interface down on a VM, when we executed the command

ifdown eth0

we got the following error:

ERROR    : [/etc/sysconfig/network-scripts/ifdown-eth] Device  has MAC address 00:00:00:00:00:00
 00:45:4D:04:02:36
 00:45:4D:04:02:40, instead of configured address 00:45:4D:16:0B:29. Ignoring.

We used ifconfig eth0 to check the information on the network interfaces which resulted in the following data:

eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
 inet 10.1.20.115  netmask 255.255.255.0  broadcast 10.1.20.255
 inet6 fe80::215:5dff:fe01:236  prefixlen 64  scopeid 0x20<link>
 ether 00:45:4d:04:02:36  txqueuelen 1000  (Ethernet)
 RX packets 10103919  bytes 5474528935 (5.0 GiB)
 RX errors 0  dropped 0  overruns 0  frame 0
 TX packets 6541413  bytes 1190276207 (1.1 GiB)
 TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

We saw that the value ether for eth0 was 00:45:4d:04:02:36, which was one of the addresses the warning mentioned that are valid.

Apparently, we had an error in the following configuration file:

/etc/sysconfig/network-scripts/ifcfg-eth0

The value for HWADDR was set to 00:45:4D:16:0B:29 which was wrong (most likely this file was copied here from another source), after we updated the value to 00:45:4d:04:02:36 we were able to use the device normally.

Start CLion as root on Fedora 1

8 February 2017 in GNU/Linux tagged clion / linux / root / x-server / xhost by Tux

Solution

Execute the following as a normal user


xhost +si:localuser:root;
sudo ./clion.sh;

Background Story and More Information

Recently we needed to start CLion as root on Fedora to allow the application we were developing to bind the DHCP service of the system.
When we tried to start CLion as root we got the following error:

java.awt.AWTError: Can't connect to X11 window server using ':0' as the value of the DISPLAY variable.

Specifically, the whole error log was as follows:

[george@bytefreaks bin]$ sudo ./clion.sh 
[sudo] password for george: 
No protocol specified

Start Failed: Failed to initialize graphics environment

java.awt.AWTError: Can't connect to X11 window server using ':0' as the value of the DISPLAY variable.
    at sun.awt.X11GraphicsEnvironment.initDisplay(Native Method)
    at sun.awt.X11GraphicsEnvironment.access$200(X11GraphicsEnvironment.java:65)
    at sun.awt.X11GraphicsEnvironment$1.run(X11GraphicsEnvironment.java:115)
    at java.security.AccessController.doPrivileged(Native Method)
    at sun.awt.X11GraphicsEnvironment.<clinit>(X11GraphicsEnvironment.java:74)
    at java.lang.Class.forName0(Native Method)
    at java.lang.Class.forName(Class.java:264)
    at java.awt.GraphicsEnvironment.createGE(GraphicsEnvironment.java:103)
    at java.awt.GraphicsEnvironment.getLocalGraphicsEnvironment(GraphicsEnvironment.java:82)
    at sun.awt.X11.XToolkit.<clinit>(XToolkit.java:126)
    at java.lang.Class.forName0(Native Method)
    at java.lang.Class.forName(Class.java:264)
    at java.awt.Toolkit$2.run(Toolkit.java:860)
    at java.awt.Toolkit$2.run(Toolkit.java:855)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.awt.Toolkit.getDefaultToolkit(Toolkit.java:854)
    at java.awt.Toolkit.getEventQueue(Toolkit.java:1734)
    at java.awt.EventQueue.isDispatchThread(EventQueue.java:1043)
    at javax.swing.SwingUtilities.isEventDispatchThread(SwingUtilities.java:1361)
    at javax.swing.text.StyleContext.reclaim(StyleContext.java:454)
    at javax.swing.text.StyleContext.addAttribute(StyleContext.java:311)
    at javax.swing.text.html.StyleSheet.addAttribute(StyleSheet.java:578)
    at javax.swing.text.StyleContext$NamedStyle.addAttribute(StyleContext.java:1501)
    at javax.swing.text.StyleContext$NamedStyle.setName(StyleContext.java:1312)
    at javax.swing.text.StyleContext$NamedStyle.<init>(StyleContext.java:1259)
    at javax.swing.text.StyleContext.addStyle(StyleContext.java:107)
    at javax.swing.text.StyleContext.<init>(StyleContext.java:87)
    at javax.swing.text.html.StyleSheet.<init>(StyleSheet.java:166)
    at javax.swing.text.html.HTMLEditorKit.getStyleSheet(HTMLEditorKit.java:391)
    at com.intellij.util.ui.UIUtil.<clinit>(UIUtil.java:102)
    at com.intellij.ide.plugins.PluginManager.start(PluginManager.java:73)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at com.intellij.ide.Bootstrap.main(Bootstrap.java:39)
    at com.intellij.idea.Main.main(Main.java:81)

This error occurred because the default configuration of the X server permissions did not allow the root to connect to it.
To verify this, we used xhost X server access control program to check the permissions.
Executing xhost with no command line arguments gave us a message indicating whether or not access control was currently enabled, followed by the list of those users allowed to connect.
For example in our case the output was as follows:


[george@bytefreaks bin]$ xhost
access control enabled, only authorized clients can connect
SI:localuser:george

To add root to the list of users that was allowed to start an X application we executed the following command:


[george@bytefreaks bin]$ xhost +si:localuser:root
localuser:root being added to access control list

Executing xhost again, we got the updated list which included the root


[george@bytefreaks bin]$ xhost
access control enabled, only authorized clients can connect
SI:localuser:root
SI:localuser:george

After this, we were able to start CLion using sudo with no problems.


[george@bytefreaks bin]$ sudo ./clion.sh

Note: This patch is not permanent, we actually execute it once at every restart of the machine.

g++ not found on Fedora 25

8 February 2017 in GNU/Linux tagged dnf / fedora / g++ / group / install by Tux

On a Fedora 25 (64bit) we got the error g++ not found.

We could have installed g++ using:


sudo dnf install gcc-c++ -y;

But we wanted to install all common additional development tools that we might need for C/C++ development in the future without going over the list of available packages to find which ones.
To do so, we installed all the packages of the group that is marked to be used for C development using dnf as follows:


sudo dnf group install "C Development Tools and Libraries" -y;

Script to clone all git repositories from all projects of a privately hosted Bitbucket server 1

21 January 2017 in Bash tagged BitBucket / clone / git / projects / repositories by Tux

The following script can download all git repositories from all of the projects that you have access to on a privately hosted Bitbucket server.

The execution work-flow of this script is as follows:

It will ask for your username (the one you use to login on the Bitbucket server)
Then it will ask for your password, the password will not be visible on screen as you type because we disabled the echo functionality for that step.
Later, you will be prompted to provide the URL of the server, for this step be sure to define the protocol if it is http or https and the correct port number as well (e.g. https://bitbucket.bytefreaks.net:7990)
Finally, you will be requested to give the location to where the repositories should be cloned to.
Then the script will connect to the server, get the list of projects that you have access to and for each project retrieve the repositories of the project and clone them in the designated folder.

[download id=”2637″]


#!/bin/bash

echo -n "Username: ";
read username;
echo -n "Password: "; 
#Disabling echo, so that password will not be visible on screen
read -s password
#Enabling echo
echo

echo -n "Server (e.g https://repository.bytefreaks.net:7990): ";
read server;
echo -n "Location to clone repositories in: ";
read location;

mkdir -p "$location";
cd "$location";

#Getting all projects
curl --user "$username:$password" "$server/rest/api/1.0/projects/" | \
  grep -oP '"key":"\K\w+' | xargs -I {} -n 1 -I_project -- sh -c \
    "curl --user \"$username:$password\" \"$server/rest/api/1.0/projects/_project/repos\" | grep -o '\"ssh:[^ ,]\+' | xargs -L1 git clone";

exit 0;