Linux and DevOps with Vijay

Cloning a VM is very useful in case of development study as well as  for production environment like working with VM ware esx server. This reduce your time and effort both. But in case of cloning existing system SSID did'nt get changed automatically and it cause network related issues.   When we clone an existing RHEL/CentOS/Scientific Linux VM  using either Oracle virtual box or Vmware workstation we find eth0 not working and instead of that there is eth1. In the same scenario if you have two NIC  for that VM  then eth0 and eth1 will not work but instead there will be eth2 eth3. So here i am telling you the solution  : Assume i have eh0 configured and i am just going to clone the VM login into the new cloned vm #cat /etc/udev/rules.d/70-persistent-net.rules there you will find new MAC ids for new interface  eth1  (" for eth0 it will show Device eth0 does not seem to be present, delaying initialisation " )   Now delete the lines having eth0 information  an

LDAP: Troubleshooting "I Have No Name!" i had an issue with my terminal server setup. We have an openldap server on RHEL 6.x and 5 number of other servers ( used for accessing ssh and telnet from student lab's thin client - for running c c++ programme) other all 5 servers have ldap authentication enabled . Now the issue was whenever i tried to log on to any of the other 5 server as user account (assume user1) it get logged in and home directory created for such new user but it shows no name found for this id and bash prompt get changed as( I have no name!@host:~$ ). i googled a lot but no success finaly i solved the issue . I used to enable cache for authentication. # authconfig --enablecache --update . so i thought i must share this to you all ... (3)

Problem: I am connecting my tata photon usb modem with ubuntu 13.04 but it is not detecting. Answer:- check whether usb_modswitch package installed $ dpkg -l | grep usb-modeswitch if it installed let we know your hardware vender id and product id. Plugin your device, open terminal and execute lsusb Identify the device, an example line could be Bus 001 Device 003: ID 12d1:1d35 Huawei Technologies Co., Ltd. Carefully take a note of numbers like ****:YYYY. The **** defines vendor Id and YYYY defines product id. In above example vendor ID is 12d1 & product ID is 1d35 Execute sudo modprobe usbserial vendor=0x**** product=0xYYYY (Replace with your vendor id and product id) now create new connection for tata give dial number and user password etc. enjoy! If everything works, execute sudo gedit /etc/modules Add the line usbserial vendor=0x**** product=0xYYYY (change vendor and product id as per your output), save and reboot.

Ques? = vmware workstation 9 on ubuntu 13.04 LTS, clicking on enter serial key but option is not opening?? Answer = just use command line to enter new serial key . sudo /usr/lib/vmware/bin/ vmware-vmx --new-sn 00000-00000-00000-00000-00000 where 00000-00000-00000-00000-00000 is your serial keys for vmware workstation 9

upgrade your rhel 5.3 to centos 5.9 how to . case study. cat /etc/redhat-release Red Hat Enterprise Linux Server release 5.3 (Tikanga) # uname -a Linux vijayrhel.mydomain.com 2.6.18-274.12.1.el5 #1 SMP Tue Nov 8 21:37:35 EST 2011 x86_64 x86_64 x86_64 GNU/Linux # cd /usr/src # wget http://mirror.centos.org/centos/5/os/x86_64/CentOS/yum-3.2.22-40.el5.centos.noarch.rpm # wget http://mirror.centos.org/centos/5/os/x86_64/CentOS/centos-release-5-9.el5.centos.1.x86_64.rpm # wget http://mirror.centos.org/ centos/5/os/x86_64/CentOS/ centos-release-5-9.el5.centos.x 86_64.rpm # wget http://mirror.centos.org/centos/5/os/x86_64/CentOS/centos-release-notes-5.9-0.x86_64.rpm # cp /etc/redhat-release /etc/redhat-release.redhat # yum -y remove rhn* # rpm --import http://mirror.centos.org/ centos/RPM-GPG-KEY-CentOS-5 # rpm -Uhv yum-3.2.22-39.el5.centos.noarc h.rpm yum-fastestmirror-1.1.16-21.el 5.centos.noarch.rpm # rpm -ev --nodeps redhat-release # rpm -ihv centos-release-5-8.el5.ce

Simple shell script to know how much active tcp connections are using your server's service ( usefull in case to know about web or ftp server or other network servers concurrent connections ) netstat -an | grep ESTABLISHED | awk '{print $5}' | awk -F: '{print $1}' | sort | uniq -c | awk '{ printf("%s\t%s\t",$2,$1) ; print "" }'

Ques:- How to use an antivirus and fire wall security for my ubuntu installed lappy or pc? Ans: A: Firewall 1. CLI manage : To enable firewall execute $sudo ufw enable This will enable ubuntu firewall and you can manage from command line. 2. GUI manage : $ sudo apt-get install gufw this will install gufw gui and will enable ufw (ubuntu firewall) This will help you to manage firewall security using gui B: Antivirus There is clamav avilable for all GNU/Linux and BSD destro : 1. CLI manage :Use $ sudo apt-get install clamav clamav-daemon clamav-freshclam to install clamav for your ubuntu. 2. GUI manage : If you wanna manage your clamav antivirus from gui there is clam tk gui front end avilable for clam av, download its .deb file from here http://sourceforge.net/ projects/clamtk/ and get it install by the command $ sudo dpkg -i clamtk_4.45-1_all.deb this will install gui to manage clam av.