Modern and performance/server grade network interface have the capability of using transmit and receive buffer description ring into the main memory. They use direct memory access (DMA) to transfer packets from the main memory to carry packets independently from the CPU. The usual default buffering values for regular desktop NICs are 256 or 512 bytes. High… Read More »
RedHat / CentOS 7 is now shipped with Grub2 which require a different approach than the well known legacy Grub. To modify Grub2 settings or kernel parameters, edit the following file : /etc/default/grub Then regenerate the Grub config as followed : grub2-mkconfig -o /boot/grub2/grub.cfg
Since Windows 8, everything is now Metro, not just the start menu, but the boot loader too! Fortunately, there is a command to disable the Metro boot loader and enable the legacy one. To do so, you will need to open the command line utility as administrator and use the following command : bcdedit /set… Read More »
Here is the two procedures to reset your Juniper SSG ScreenOS device. The first method (if you have the password for your device) and serial connection to your device, you can do a software reset as followed. 1. Get your device serial number using the following command (or by reading the label on your device)… Read More »
Here is how to open a port and make it permanent with the new firewalld on RedHat/CentOS Linux 7. You can statically edit /etc/firewalld/zones/zone.conf and reload the daemon, but the right way to do is the following. 1. Open the port by specifying the proper zone, port number and protocol. Unless you do not want… Read More »
You may ran into the following issue with Firefox browsing a SSL Web site using self generated certificate : sec_error_reused_issuer_and_serial The cause is that the self generated certificate of the site you are browsing have the same serial number of a previously stored certificate (another Web site you already visited and manually added an exception… Read More »
Here is a quick how to restrict the availability of the WebUI to one or several interface VLan(s) and specify which remote/management IPs should be allowed to access it. 1. Set the web management service to the interface VLan you want it to answer from external requests (this example assume that the l3-interface vlan.10 will… Read More »
Here is a quick list of useful commands for any MySQL database administrator. Show the server full status : mysqladmin -u root -p extended-status You may also sort specific information with “grep” as followed : mysqladmin -u root -p extended-status | grep Threads Show the current running process and queries (remove “-i 1” to display… Read More »
VMware ESXi hypervisor have some great SNMP capability, whatever to gather information status of your hardware, monitoring or statistic usage of your resources. Follow these easy steps to enable such feature. 1. Enable SSH from the vSphere client and connect to it using your favorite terminal application : Configuration tab > Security Profile > Services >… Read More »
Using cURL, you can easily grab some information about the server who’s running a Web site. To get all the possible information, simply use (replace domain.tld with the actual domain name) : curl -s -I domain.tld You can also can just output the server info like this : # curl -s -I microsoft.com|grep Server Server:… Read More »