Post describes procedure to disable IPv6 on CentOS/RHEL 6. There are 2 ways to do this : 1. Disable IPv6 in kernel module (requires reboot) 2. Disable IPv6 using sysctl settings (no reboot required) Method 1 : using /etc/modprobe.d/ipv6.conf 1. Check if IPV6 is enabled: # ifconfig |grep inet6 inet6 addr: fe80::d6be:d9ff:fe99:5a77/64 Scope:Link inet6 addr: […]
Archives for May 2016
Netbackup Script to get client Vs policy list
Here is a small script to get the list of policies configured against a list of clients using netbackup commandline. Command used is bpplclients to get the clients. Put the list of policy in a file /tmp/policy_list. # cat /tmp/policy_list policy01 policy02 policy03 The script : for i in `cat /tmp/policy_list` do bpplclients $i -noheader […]
Solaris netstat : Understanding the output when displaying routing table
The post describes the meaning of the flags that are displayed in the routing tables when you use the netstat command. Sample output: # netstat -rn Routing Table: Destination Gateway Flags Ref Use Interface ——————– ——————– —– —– —– ——— 127.0.0.1 127.0.0.1 UH 021220517 lo0 192.9.200.0 207.82.202.188 UG 0 93 192.9.200.0 207.82.202.65 UG 0 0 […]
How to Disable or set SELinux to Permissive mode
Question : How to fully disable SELinux (Security Enhanced Linux) or set it to “permissive” mode Answer : SELinux gives that extra layer of security to the resources in the system. It provides the MAC (mandatory access control) as contrary to the DAC (Discretionary access control). Before we dive into setting the SELinux modes, let […]
CentOS / RHEL 7 : Booting process
It is important to understanding the Linux boot process to troubleshoot boot problems. These are the high-level steps in the boot process. You need to be aware of files involved in the boot process because errors in these files can cause boot problems. If there is an issue during boot, you need to identify in […]
CentOS / RHEL 7 : How to Change the machine-id
What is machine-id – The /etc/machine-id file contains the unique machine ID of the local system that is set during installation. The machine ID is a single newline-terminated, hexadecimal, 32-character, lowercase machine ID string. When decoded from hexadecimal, this corresponds to a 16-byte/128-bit string. – The “machine-id” parameter is added from RHEL 7.1 to identify […]
Solaris 11 : How to configure VLAN tagging on a network interface
A virtual local area network (VLAN) are basically used to isolate groups of users from each other for ease of network administration and security. In Solaris 11, VLANs are created using dladm and the IP address is assigned using ipadm. The post describes configuration of VLAN tagging on network interface with an example. Configuration To […]
How to Check whether SELinux is Enabled or Disabled
Question : How to Check whether SELinux is Enabled or Disabled Answer : SELinux gives that extra layer of security to the resources in the system. It provides the MAC (mandatory access control) as contrary to the DAC (Discretionary access control). Before we dive into setting the SELinux modes, let us see what are the […]
Downloading a Specific Version of Package and Its Dependencies from Repository for Offline Installation Using YUM
Question : How to download a specific version of the package along with its dependencies using YUM offline. Answer : 1. To see what particular versions are available to you via yum you can use the –showduplicates switch. # yum –showduplicates list [package_name] For Example : # yum –showduplicates list httpd Loaded plugins: product-id, security, […]
CentOS / RHEL : Exclusion with Yum For Kernel Updates
Question : How to make an exclusion list so that anyone running the command “yum update” will not download any kernel patches ? Answer : This can be done using 2 ways : 1. yum configuration file yum.conf (permanent) 2. Using command line options Using yum.conf 1. From the man page of yum.conf : # […]