A couple of useful AWK Tutorial to guide you through learning and mastering Awk :
Per Fail2ban main page, Fail2ban is the de facto tool to have to monitor malicious access attempts on your server and ban source IPs if need be.
The 2 presentations presents Fail2Ban’s history and features in a very-well manner :
The warning message below has been displayed after upgrading Debian testing :
W: Possible missing firmware /lib/firmware/i915/kbl_guc_ver9_14.bin for module i915
W: Possible missing firmware /lib/firmware/i915/bxt_guc_ver8_7.bin for module i915
This issue has been referenced in the Debian bug tracking system : #857997
For now, this package does not provide the latest version of Kabylake GuC (9.14) and Broxton GuC (8.7) firmwares.
To remove this warning message, as a workaround, just download them and copy the blob files into the directory /lib/firmware/i915.
Finally, rebuild your initramfs :
update-initramfs -k `uname -r`-u
Upgrade a rpm package on a couple of servers with a quick one-liner in Ansible :
ansible all -b --ask-become-pass -m yum "name=bash state=latest"
servers_list is the text file listing your servers.
Using the ANSIBLE_INVENTORY variable overrides the use of a generate inventory.
This one-liner makes use of the yum Ansible module.
Running sudo commands is possible with these options -b and –ask-become-pass
After a fresh installation of CentOS 7, your main network interface may be disabled. Its name may be enp0s3.
Check its status with :
nmcli dev status
To enable it permanently, look at its configuration file at /etc/sysconfig/network-scripts/ifcfg-enp0s3 and make the change from :
Restart the network service :
systemctl restart NetworkManager
The network interface status should now be as connected :
nmcli dev status
Sometimes, Winbind does not reflect AD group membership change. How to recover from it ?
The below steps have been successfully tested on a Red Hat server :
Get OS version :
Get Winbind version :
Stop Winbind service :
service winbind stop
Flush any Winbind cache :
net cache flush
Delete all tdb files :
rm -rf /var/lib/samba/*.tdb
Restart Winbind service :
service winbind start
Look up details for a given user :
If you push code to a git repo, you might get this error :
remote: error: insufficient permission for adding an object to repository database objects
remote: fatal: failed to write object
Make sure that the system permissions are set properly. Stackoverflow provides some good troubleshooting steps.
The commands below solve the issue :
chgrp -R groupname .
chmod -R g+rwX .
git config core.sharedRepository true
For groupname, make sure it matches the user account details that you use for logging in and pushing code to the git server.