Question: what is the proper procedure to reconfigure the docker interface to use an address range (e.g., > 172.200) for the virtual interfaces it uses? You can reconfigure the default bridge network by providing the bip option along with the desired subnet in the daemon.json (default location at /etc/docker/daemon.json ) file as follows: # vi /etc/docker/daemon.json { "bip": "172.200.0.1/16" } Then restart the docker daemon as root. On CentOS/RHEL 6 use the service command to … [Read more...] about How to change the default IP address of docker bridge
Linux
“su: Authentication failure” – in Docker
The Problem In some situations, a normal user within a Docker container cannot run 'su' command to switch user. When 'su' command is issued, the following error returns. $ su - Password: [entering correct password] su: Authentication failure The Solution The sticky permission may be missing in /usr/bin/su within the container. With root privilege, you may fix as follows: 1. First check the current permissions for the /usr/bin/su binary file. # ls -l /usr/bin/su -rwxr-xr-x 1 root … [Read more...] about “su: Authentication failure” – in Docker
How to find docker storage device and its size (device mapper storage driver)
Question: How to find the running docker storage device when docker is using the device-mapper storage driver and then check the size of it? 1. Please run the "docker info" command to display docker system-wide information which contains the docker storage info. # docker info Containers: 0 Running: 0 Paused: 0 Stopped: 0 Images: 0 Server Version: 18.03.1-ol Storage Driver: devicemapper Pool Name: docker-251:0-102683530-pool Pool Blocksize: 65.54kB Base Device Size: … [Read more...] about How to find docker storage device and its size (device mapper storage driver)
‘docker images’ command error – “Permission Denied”
The Problem A regular user is not able list images using docker images command. Following error can be observed. user01> docker images Got permission denied while trying to connect to the Docker daemon socket at unix:///var/run/docker.sock: Get http://%2Fvar%2Frun%2Fdocker.sock/v1.27/images/json: dial unix /var/run/docker.sock: connect: permission denied The Solution User is not part of docker group and doesn't have permissions to execute docker related commands. Add regular user to … [Read more...] about ‘docker images’ command error – “Permission Denied”
How to change the interface name in CentOS/RHEL 8 using prefixdevname
This post will help to change the network interface name using prefixdevname utility in CentOS/RHEL 8 systems. Installation and configuration 1. Install the required package using dnf utility: # dnf install prefixdevname 2. Append the net.ifnames.prefix=[ABCD] using grubby command: (ABCD to replaced with own prefix, eg: net). # grubby --update-kernel=$(grubby --default-kernel) --args="net.ifnames.prefix=net" 3. Reboot the system to take effect: # reboot 4. After system rebooted, … [Read more...] about How to change the interface name in CentOS/RHEL 8 using prefixdevname
How to configure EPEL repository in OEL 7
Question: How to install/get packages from EPEL Repository on OEL 7? 1. Create a repo file like /etc/yum/repos.d/epel-yum-ol7.repo. For example: # cat /etc/yum.repos.d/epel-yum-ol7.repo [ol7_epel] name=Oracle Linux $releasever EPEL ($basearch) baseurl=http://yum.oracle.com/repo/OracleLinux/OL7/developer_EPEL/$basearch/ gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-oracle gpgcheck=1 enabled=1 2. And then run "yum repolist" command to see if repository is in there. # yum … [Read more...] about How to configure EPEL repository in OEL 7
How to re-create the yum cache (force a fetch of the cache data) from enabled repositories in CentOS/RHEL
This post briefly outlines how it possible to re-create the yum cache, or said in another way, force a fetch of the cache data from the enabled yum repositories. The enabled yum repositories are the ones in the following file /etc/yum.conf or in the following folder /etc/yum.repos.d that have their "enabled" setting to "1", e.g. : # vi /etc/yum.repos.d/test.repo [test_repo] name=Test … [Read more...] about How to re-create the yum cache (force a fetch of the cache data) from enabled repositories in CentOS/RHEL
How to Create yum Repository in CentOS/RHEL
1. Create a directory for you local repository, e.g. /home/mypackage_dir/repository. Move the RPMs into that directory. # mkdir /home/mypackage_dir/repository # cp /media/packages/* /home/mypackage_dir/repo 2. Fix some ownership and filesystem permissions: # chown -R root:root /home/mypackage_dir/repo 3. Install the createrepo package if not installed yet, and run: # createrepo /home/mypackage_dir/repo # chmod -R o-w+r /home/mypackage_dir/repo 4. Create a repository configuration … [Read more...] about How to Create yum Repository in CentOS/RHEL
How to Disable Client Access Control in MySQL
You can disable the client access control in MySQL by telling the server not to read the grant tables and disable access control. Use the --skip-grant-tables option to do so. The --skip-grant-tables option has the following effects: When connected, the user has full privileges to do anything. This option disables account management statements such as CREATE USER, GRANT, REVOKE, and SET PASSWORD. Disabling access control is convenient if you forget the root password and need to reset it … [Read more...] about How to Disable Client Access Control in MySQL
How to Disable NetworkManager in CentOS/RHEL 8
Although NetworkManager is the default tool for configuring and managing the network services on CentOS/RHEL 8, there are situations where it may be necessary to permanently disable NetworkManager, and use alternative methods to configure and manage the network. This document describes how to permanently disable NetworkManager on CentOS/RHEL 8. Note: Use of "networks-scripts" is deprecated in CentOS/RHEL 8. Disabling NetworkManager in CentOS/RHEL 8 1. The following three commands are … [Read more...] about How to Disable NetworkManager in CentOS/RHEL 8