Linux Admin / RHEL7 / Unix Intermediate
by Ramdev · Published June 26, 2015 · Last modified August 23, 2015
Red Hat allows you to install the OS over the network using NFS, FTP or HTTP. If the hardware supports PXE (Pre-eXecution Environment) the NIC card will send out a broadcast request for DHCP information. The DHCP server provides the client with a IP address and...
Linux Admin / Redhat Enterprise Linux 6 / Unix Intermediate
by Ramdev · Published June 25, 2015 · Last modified August 23, 2015
What is a Leap Second? A leap second is a second which is added to Coordinated Universal Time (UTC) in order to synchronize atomic clocks with astronomical time to within 0.9 seconds.A leap second is added (can be removed but this never actually happens in reality) on the...
Linux Admin / Linux Disk Management / Linux LVM / Storage Configs for Unixadmin / Storage Migrations / Unix Intermediate
by Ramdev · Published June 16, 2014 · Last modified August 6, 2016
Sudo is different from the su command and is more flexible and more secure. The sudo command allows users to do tasks on a Red Hat Enterprise Linux system as another user. One significant advantage is that it can log usage. By default the program saves...
Linux Admin / Linux Networking / Unix Intermediate
by Ramdev · Published June 12, 2014 · Last modified March 3, 2016
1. Network does not start due to “Device not managed by Network-Manager” error. Generally, this error occurs when the ethernet cable does not connect to the interface well and the interface is not configured properly. The solution for this issue is to ensure the link...
Linux Admin / Linux Networking / Unix Intermediate
by Ramdev · Published June 12, 2014 · Last modified August 21, 2015
This is post is to explain the configuration of a linux VM with a secondary NIC without reboot or restart network services. This is fairly simple and straight forward task, but I am just posting it for the folks who are new for the Linux VM...
Setting Kernel parameters permanently in Red hat Enterprise Linux Every time the system boots, the ‘/etc/rc.d/rc.sysinit‘ script is executed by init process. This shell script contains a call to sysctl command and reads the values from /etc/sysctl.conf file as the ones to be set Therefore, any...
EMail Posts / Linux Admin / Linux Networking / Redhat Enterprise Linux 6 / Unix Intermediate
by Ramdev · Published June 12, 2014 · Last modified March 11, 2016
NTP stands for Network Time Protocol, and it is an Internet protocol used to synchronize the clocks of computers to some time reference. NTP is an Internet standard protocol originally developed by Professor David L. Mills at the University of Delaware. Time usually just advances. If you have communicating programs running on different computers, time still...
Linux Admin / Linux Networking / Redhat Enterprise Linux 6 / Unix Intermediate
by Ramdev · Published June 12, 2014 · Last modified July 2, 2015
A chroot on Unix operating systems is an operation that changes the apparent root directory for the current running process and its children. A program that is run in such a modified environment cannot name and cannot access files outside the designated directory tree. Chroot sftp...
Linux Admin / Linux Troubleshooting / Performance Analysis / Redhat Enterprise Linux 6 / Unix Intermediate
by Ramdev · Published June 9, 2014 · Last modified July 23, 2016
Guidelines to Implement Audit Rules: – Consolidate your rules where possible. – The system call rules are loaded into a matching engine that intercepts each syscall that all programs on the system makes. – It is very important to only use syscall rules when you have...
Linux Admin / Linux Networking / Redhat Enterprise Linux 6 / Unix Intermediate
by Ramdev · Published June 5, 2014 · Last modified July 2, 2015
In Red Hat Enterprise Linux 3 or later FTP service is provided by the vsftpd daemon. vsftpd stands for “Very Secure FTP Daemon” and is an FTP server for Unix-like systems. It supports IPv6 and SSL, as well as explicit and implicit FTPS. The vsftpd daemon...
