Reset root password by accessing file system on Guest OS from Physical host - CentOS

Everyone know as how to reset your forgotten root password on Linux - (http://goo.gl/6j9u2k), but in this article since I'm using Guest OS on KVM hypervisor, I would demonstrate as how to mount the root file system and reset password.

Details:

Hostname: kvm1

Diskname: vm1

path:     /var/lib/libvirt/images/vm1.img 

- Firstly, you need to shutdown your VM, doing it which it's running can cause disk corruption.

#virsh shutdown vm1

- Check your VM is in shut off state

#virsh list --all

- Get an unused loop device

#losetup -f

/dev/loop0

- Map VM image to your loop device

#losetup /dev/loop0 /var/lib/libvirt/images/vm1.img

- Print your partition table of the image file which is been mapped to the loop device and identify the correct partition where your root file system mounted upon.

#fdisk -l /dev/loop0

Disk /dev/loop0: 10.7 GB, 10737418240 bytes

255 heads, 63 sectors/track, 1305 cylinders, total 20971520 sectors

Units = sectors of 1 * 512 = 512 bytes

Sector size (logical/physical): 512 bytes / 512 bytes

I/O size (minimum/optimal): 512 bytes / 512 bytes

Disk identifier: 0x000907df

      Device Boot      Start         End      Blocks   Id  System

/dev/loop0p1   *        2048     1050623      524288   83  Linux

/dev/loop0p2         1050624     3147775     1048576   82  Linux swap / Solaris

/dev/loop0p3         3147776    20971519     8911872   83  Linux

- In order to mount the VM's partitions, you need to create partition mappings

#kpartx -av /dev/loop0

Disk /dev/loop0: 10.7 GB, 10737418240 bytes

255 heads, 63 sectors/track, 1305 cylinders, total 20971520 sectors

Units = sectors of 1 * 512 = 512 bytes

Sector size (logical/physical): 512 bytes / 512 bytes

I/O size (minimum/optimal): 512 bytes / 512 bytes

Disk identifier: 0x000907df

      Device Boot      Start         End      Blocks   Id  System

/dev/loop0p1   *        2048     1050623      524288   83  Linux

/dev/loop0p2         1050624     3147775     1048576   82  Linux swap / Solaris

/dev/loop0p3         3147776    20971519     8911872   83  Linux

- Here my root file system was on /dev/vda3 which is associated with 

/dev/loop0p3 which would be mounted.

#mount /dev/mapper/loop0p3 /mnt

- remove password field from root user in /etc/shadow 

#vim /mnt/etc/shadow

Note: If your system has been enabled with SELinux, it is very much required to autorelabel else you will be unable to login. Check below snap.

#touch /mnt/.autorelabel

- Once done, remove your mappings and start the VM. 

#umount /mnt

#kpartx -dv /dev/loop0

#losetup -d /dev/loop0

- Start your VM 

#virsh start vm1

- In your console, when you login with 'root' without providing any password.

zfs cheat sheet - Creation of Storagepools & Filesystems using zpool & zfs #Solaris 11

The ZFS file system is a file system that fundamentally changes the way file systems are administered, with features and benefits not found in other file systems available today. ZFS is robust, scalable, and easy to administer.ZFS uses the concept of storage pools to manage physical storage, ZFS eliminates volume management altogether. Instead of forcing you to create virtualized volumes, ZFS aggregates devices into a storage pool.File systems are no longer constrained to individual devices, allowing them to share disk space with all file systems in the pool. You no longer need to predetermine the size of a file system, as file systems grow automatically within the disk space allocated to the storage pool. When new storage is added, all file systems within the pool can immediately use the additional disk space without additional work

zpool commands	Description
zpool create testpool c0t0d0	Create simple pool named testpool with single disk creating default mount point as poolname(/testpool) OPTIONAL: -n do a dry run on pool creation -f force creation of the pool
zpool create testpool mirror c0t0d0 c0t0d1	Create testpool mirroring c0t0d0 with c0t0d1 creating default mount point as poolname(/testpool)
zpool create -m /mypool testpool c0t0d0	Create pool with different mount point than default
zpool create testpool raidz c2t1d0 c2t2d0 c2t3d0	Create RAID-Z testpool
zpool add testpool raidz c2t4d0 c2t5d0 c2t6d0	Add RAID-Z disks to testpool
zpool create testpool raidz1 c2t1d0 c2t2d0 c2t3d0 c2t4d0 c2t5d0 c2t6d0	Create RAIDZ-1 testpool
zpool create testpool raidz2 c2t1d0 c2t2d0 c2t3d0 c2t4d0 c2t5d0 c2t6d0	Create RAIDZ-2 testpool
zpool add testpool spare c2t6d0	Add spare device to the testpool
zpool create testpool mirror c2t1d0 c2t2d0 mirror c2t3d0 c2t4d0	Disk c2t1d0 mirrored with c2t2d0 & c2t3d0 mirrored with c2t4d0
zpool remove testpool c2t6d0	Removes hot spares and cache disks
zpool detach testpool c2t4d0	Detach the mirror from the pool
zpool clear testpool c2t4d0	Clears specific disk fault
zpool replace testpool c3t4d0	Replace disk like disk
zpool replace testpool c3t4d0 c3t5d0	Replace one disk with another disk
zpool export testpool	Export the pool from the system
zpool import testpool	Imports specific pool
zpool import -f -D -d /testpool testpool	Import destroyed testpool
zpool import testpool newtestpool	Import a pool originally named testpool under new name newtestpool
zpool import 88746667466648	Import pool using ID
zpool offline testpool c2t4d0	Offline the disk in the pool Note: zpool offline testpool -t c2t4d0 will offline temporary
zpool upgrade -a	upgrade all pools
zpool upgrade testpool	Upgrade specific pool
zpool status -x	Health status of all pools
zpool status testpool	Status of pool in verbose mode
zpool get all testpool	Lists all the properties of the storage pool
zpool set autoexpand=on testpool	Set the parameter value on the storage pool Note: zpool get all testpool gives you all the properties on which it could be used to set value
zpool list	Lists all pools
zpool list -o name,size,altroot	show properties of the pool
zpool history	Displays history of the pool Note: Once the pool is removed, history is removed.
zpool iostat 2 2	Display ZFS I/O stastics
zpool destroy testpool	Removes the storage pool

zfs commands	Description
zfs list	Lists the ZFS file system's zfs list -t filesystem zfs list -t snapshot zfs list -t volume
zfs create testpool/filesystem1	Creates ZFS filesystem on testpool storage
zfs create -o mountpoint=/filesystem1 testpool/filesystem1	Different mountpoint created after ZFS creation
zfs rename testpool/filesystem1 testpool/filesystem2	Renames the ZFS filesystem
zfs unmount testpool	unmount the storagepool
zfs mount testpool	mounts the storagepool
NFS exports in ZFS	zfs share testpool - shares the file system for export zfs set share.nfs=on testpool - make the share persistent across reboot svcs -a nfs/server - NFS server should be online cat /etc/dfs/dfstab - Exported entry in the file showmount -e - storage pool has been exported
zfs unshare testpool	Remove NFS exports
zfs destroy -r testpool	Destroy storage pool and all datasets under it
zfs set quota=1G testpool/filesystem1	set quota of 1GB on the filesystem1
zfs set reservations=1G testpool/filesystem1	set reservation of 1GB on the filesystem1
zfs set mountpoint=legacy testpool/filesystem1	Disable ZFS auto mounting and enable through /etc/vsftab
zfs unmount testpool/filesystem1	unmounts ZFS filesystem1 in testpool
zfs mount testpool/filesystem1	mounts ZFS filestystem1 in testpool
zfs mount -a	mounts all the ZFS filesystems
zfs snapshot testpool/filesystem1@friday	Creates a snapshot of the filesystem1
zfs hold keep testpool/filesystem1@friday	Holds existing snapshot & attempts to destroy using zfs destroy will fail
zfs rename testpool/filesystem1@friday FRIDAY	Rename the snapshots Note: snapshots must exists in the same pools
zfs diff testpool/filesystem1@friday testpool/filesystem1@friday1	Identify the difference between two snapshots
zfs holds testpool/filesystem1@friday	Displays the list of snapshots help
zfs rollback -r testpool/fileystem1@friday	Roll back yesterday snapshot recursively
zfs destroy testpool/fileystem1@thursday	Destroy snapshot created yesterday
zfs clone testpool/filesystem1@friday testpool/clones/friday	Clone was created on the same snapshot Note: Cannot create clone of a filesystem in a pool that is different from where original snapshot resides.
zfs destroy testpool/clones/Friday	Destroy the clone

Thanks,

Create Local Repository - Solaris 11.2

Image packaging system(IPS) and important concept from Solaris 11 onwards. I would like to create local repository on the local system by downloading the files from the Oracle website using oracle's automated script.

Download below files and copy to your local Solaris server.

Below are the files copied on my local Solaris server. 

root@solnode1:/var/share/pkg# pwd

/var/share/pkg

root@solnode1:/var/share/pkg# ls -l

total 14373953

-rwx------   1 root     root        5594 Aug 29 20:52 install-repo.ksh

drwxr-xr-x   3 pkg5srv  pkg5srv        7 Aug 30 08:42 repositories

-rw-r--r--   1 root     root     1771800121 Aug 29 15:32 sol-11_2-repo-1of4.zip

-rw-r--r--   1 root     root     1889867782 Aug 29 15:35 sol-11_2-repo-2of4.zip

-rw-r--r--   1 root     root     1902167161 Aug 29 16:46 sol-11_2-repo-3of4.zip

-rw-r--r--   1 root     root     1790358735 Aug 29 16:44 sol-11_2-repo-4of4.zip

-rw-r--r--   1 root     root         227 Aug 29 16:14 sol-11_2-repo-md5sums.txt

root@solnode1:/var/share/pkg#

root@solnode1:/var/share/pkg#./install-repo.ksh -d /var/share/pkg/repositories/ -v -c

The script would compare the checksums of the downloaded files, uncompress and would initiate the repository creation. 

your current publisher would be pointing to "pkg.oracle.com" and it needs to be changed to your local repository. 

root@solnode1:~# pkg publisher

PUBLISHER                   TYPE     STATUS P LOCATION

solaris                     origin   online F http://pkg.oracle.com/solaris/release/

root@solnode1:~#

root@solnode1:~# pkg set-publisher -G '*' -M '*' -g file:///var/share/pkg/repositories solaris

root@solnode1:~#

root@solnode1:~# pkg publisher

PUBLISHER                   TYPE     STATUS P LOCATION

solaris                     origin   online F file:///var/share/pkg/repositories/

root@solnode1:~#

To enable clients to access the local repository via HTTP, enable the application/pkg/server Service Management Facility (SMF) service.

root@solnode1:~# svccfg -s application/pkg/server setprop pkg/inst_root=/var/share/pkg/repositories

root@solnode1:~# 

check does repos work

root@solnode1:~# svcprop -p pkg/inst_root application/pkg/server

/var/share/pkg/repositories

root@solnode1:~#

Reload the pkg.depotd repository service.

root@solnode1:~# svcadm refresh application/pkg/server

root@solnode1:~#

we had successfully created solaris 11.2 local repository.

Contiguous space re-partition - Linux

To recap, root FS has run out of space and data contained on it couldn't be removed or compressed to free up the space. Since there was swap space, so I planned to reclaim from the swap partition without losing the data and would extend the space for root file system. 

Host : susenode2

OS   : SuSE 11 / CentOS / Redhat 

Disk : sda

It could have been easy we could have extended volume using LVM, since our disks are not under LVM, we are here trying to re-create the entire partition without losing data.

Current scenario :

Disk (sda) is been into 3 partitons, of which sda1, sda2 are my data partitions & sda3 swap partition. I would recreate the swap partition and would extend the root file system. It could also be seen that the sector are contiguous between sda2 and sda3 hence I could destroy those two partitions and re-create.

df & fdisk & swap output :

susenode2:~ # df -hT

Filesystem     Type   Size  Used Avail Use% Mounted on

/dev/sda2      ext3    13G   12G  570M  96% /

udev           tmpfs  369M  128K  369M   1% /dev

tmpfs          tmpfs  369M     0  369M   0% /dev/shm

/dev/sda1      ext3   1.1G 1015M   18M  99% /application/logs

susenode2:~ #

susenode2:~ # fdisk -l /dev/sda

Disk /dev/sda: 21.5 GB, 21474836480 bytes

255 heads, 63 sectors/track, 2610 cylinders, total 41943040 sectors

Units = sectors of 1 * 512 = 512 bytes

Sector size (logical/physical): 512 bytes / 512 bytes

I/O size (minimum/optimal): 512 bytes / 512 bytes

Disk identifier: 0x000cc8af

   Device Boot      Start         End      Blocks   Id  System

/dev/sda1            2048     2265087     1131520   83  Linux

/dev/sda2   *     2265088    31625215    14680064   83  Linux                  <<===  root fs

/dev/sda3        31625216    41943039     5158912   82  Linux swap / Solaris   <<===  swap 

susenode2:~ #

susenode2:~ # swapon -s

Filename                                Type            Size    Used    Priority

/dev/sda3                               partition       5158908 0       -1

susenode2:~ #

Since we are resizing the root file system, we need to get into rescue environment to do so. 

I am using an SuSE DVD or you could also use knoppix and would get into rescue environment and make necessary changes to the partition table. 

I would delete the partition sda2 and sda3 and would recreate the sda2 from the sector which was at the start i..e 2265088 and would end for my required size say 18G which I would add to this file system.

I would later create a new partition for the swap for remaining space. 

snaps are as below :

Once partition are created we need to change the type of the partition to swap for sda3 and since sda2 was bootable, make sure you would toggle boot flag on the partition.

Make sure you now has enough space in the disk where you could resize your root file system and make the swap partition. 

Rescue:~ # mkswap /dev/sda3

Rescue:~ # reboot

After reboot, check your root file system space. It would have been increased and swap space decreased. 

Snap after increasing file system :

susenode2:~ # df -hT

Filesystem     Type   Size  Used Avail Use% Mounted on

/dev/sda2      ext3    18G   12G  5.3G  69% /

udev           tmpfs  369M  128K  369M   1% /dev

tmpfs          tmpfs  369M     0  369M   0% /dev/shm

/dev/sda1      ext3   1.1G 1015M   18M  99% /application/logs

susenode2:~ #

susenode2:~ # fdisk -l /dev/sda

Disk /dev/sda: 21.5 GB, 21474836480 bytes

255 heads, 63 sectors/track, 2610 cylinders, total 41943040 sectors

Units = sectors of 1 * 512 = 512 bytes

Sector size (logical/physical): 512 bytes / 512 bytes

I/O size (minimum/optimal): 512 bytes / 512 bytes

Disk identifier: 0x000cc8af

   Device Boot      Start         End      Blocks   Id  System

/dev/sda1            2048     2265087     1131520   83  Linux

/dev/sda2   *     2265088    40013823    18874368   83  Linux

/dev/sda3        40013824    41943039      964608   82  Linux swap / Solaris

susenode2:~ #

susenode2:~ # swapon -s

Filename                                Type            Size    Used    Priority

/dev/sda3                               partition       964604  0       -1

susenode2:~ #

Thanks

speedtest mini : check your internet speed locally - CentOS 7

speedtest.net is one of the most popular internet speed tests. It is very helpful if you want to determine your Internet download and upload speed similarly speedtest-mini can be performed on local server. 

Install your apache, PHP,  start httpd service and make sure 'httpd' service is allowed by your firewall. 

#yum install -y httpd php php-mysql php-gd php-mcrypt

#systemctl start httpd

#firewall-cmd --add-service=http 

Download "speedtest mini" from speedtest.net from their official site : 

#cd /var/www/html

Register to speedtest.net and download the latest version of mini. 

#wget http://c.speedtest.net/mini/mini.zip

#unzip mini.zip

Make sure your apache doccument root is in /var/www/html

# grep -i "^documentroot" /etc/httpd/conf/httpd.conf

DocumentRoot "/var/www/html"

#cd /var/www/html/mini

#mv index-php.html index.html

point your browser to http://<ipaddress>/mini and start testing your speed on the local servers. 

Thanks

Configure Network Teaming - RHEL 7

Network teaming is method for linking NIC's together logically to allow for failover or higher throughput. 

RHEL 7 implements network teaming with a small kernel driver and a user space daemon, teamd. The kernel handles network packets efficiently and teamd handles logic and interface processing. Software, called runners, implement load balancing and active-backup logic, such as roundrobin. The following runners are available to teamd:

- broadcast : a simple runner transmits each packet from all ports

- roundrobin : simple runner which transmits packets in a rounf-robin fashion from each port

- activebackup : failover runner which watches for link changes and selects an active port for data transfers

- loadbalance : this runner monitors traffic and uses a hash function to try to reach a perfect balance when selecting ports for packet transmission.

- lacp : implements the 802.3ad Link aggregation control protocol. can use the same transmit port selection possibilities as the loadbalance runner.

Steps:

- Create team interface 

- Assigning the IPv4 or IPv6 attributes of the team interface

- Assign the port interfaces

- Bring the team and port interfaces up/down

Current existing network interfaces are beow, "eno33554984" and "eno50332208" will be the interfaces that will be the ports for the teamed interface.

# ip link

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT

    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00

2: eno16777736: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP mode DEFAULT qlen 1000

    link/ether 00:0c:29:14:ef:0e brd ff:ff:ff:ff:ff:ff

3: eno33554984: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP mode DEFAULT qlen 1000

    link/ether 00:0c:29:14:ef:18 brd ff:ff:ff:ff:ff:ff

4: eno50332208: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP mode DEFAULT qlen 1000

    link/ether 00:0c:29:14:ef:22 brd ff:ff:ff:ff:ff:ff

#

- Create team interface:

# nmcli connection add type team con-name team0 ifname team0 config '{"runner": {"name": "activebackup"}}'

Connection 'team0' (b781d554-6d28-4baa-9af8-5f3331acd427) successfully added.

#

'{"runner": {"name": "activebackup"}}' - In this setup i'm using method 'activebackup' 

- Assign IPv4 attributes to team interface.

# nmcli connection modify team0 ipv4.addresses '192.168.229.181/24'

# nmcli connection modify team0 ipv4.method manual

- assign the port interfaces

# nmcli connection add type team-slave con-name team0-port1 ifname eno33554984 master team0

Connection 'team0-port1' (d7ae4a56-4872-4264-8f2f-215742deae92) successfully added.

# nmcli connection add type team-slave con-name team0-port2 ifname eno50332208 master team0

Connection 'team0-port2' (c6755f4b-8071-4294-b3d5-691da53cf264) successfully added.

#

- check the current state of teamed interfaces. 

# ip a show team0

7: team0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP

    link/ether 00:0c:29:14:ef:18 brd ff:ff:ff:ff:ff:ff

    inet 192.168.229.181/24 brd 192.168.229.255 scope global team0

       valid_lft forever preferred_lft forever

    inet6 fe80::20c:29ff:fe14:ef18/64 scope link

       valid_lft forever preferred_lft forever

#

# teamdctl team0 state

setup:

  runner: activebackup

ports:

  eno33554984

    link watches:

      link summary: up

      instance[link_watch_0]:

        name: ethtool

        link: up

  eno50332208

    link watches:

      link summary: up

      instance[link_watch_0]:

        name: ethtool

        link: up

runner:

  active port: eno33554984

#

Ping from your network gateway through the 'team0' interface, and when the 'eno33554984' || 'eno50332208' have been disconnected, you still have no interruptions in the PING. 

how to disconnect one of the interface:

#nmcli device disconnect eno33554984

#teamdctl team0 state

#nmcli device connect eno33554984

- Display team ports of the team0 interface

# teamnl team0 ports

- Display the active port

# teamnl team0 getoption activeport

Thanks

Install and configure Git - CentOS 7

In this article i'll try to explain how to install, configure and use Git.

Environment: CentOS 7

Git version: 1.8.3.1

Git is a distribute version control system used by developers, but since it can also store .files(files with '.') system admin's can use to store their customized configurations files like .bashrc, .vimrc or other important scripts ..etc

Git takes a snapshot of how the files look at that instant in time and will store a reference to it. It wouldn't matter to Git what data you insert as it will check-sum it using SHA1 algorithm and create 40-character hex key. Git is based on key-value data system.

- Install Git by using 'yum' 

#yum install git -y

# git --version

git version 1.8.3.1

#

I already have a Git account registered if you don't have, signup to http://www.github.com and complete your registration. create your first repository by '+' 

NOTE: repository name you choose or the directory name which you create should be the alike. Git usually sync the directory or the files from your laptop or desktop to the one having the same name as in the GitHub.

 

setup your name and e-mail (similar email ID that you used to create GitHub account) on your local laptop or desktop which must be run very first time inorder to setup Git.

sunilka@centos7]$ git config --global user.name "sunilka"

sunilka@centos7]$ git config --global user.email "sunilka@gmail.com"

sunilka@centos7]$ git config --list

Create a directory and initialize Git by running git init, after that you have .git created with few files and directory under it. According to Git it's now been the working tree. now, everything under it can be uploaded to GitHub.

sunilka@centos7]$ mkdir configs

sunilka@centos7]$ cd configs; git init

sunilka@centos7]$ ls -ld .git

few files were been created and added into the directory, the moment we added the files into Git it creates a hash checksum and refers it by checksum.

sunilka@centos7 configs]$ git ls-files --stage

100755 af7ec7a5b7b361c10dcbf3db7286f97ef7df57d6 0       ks.cfg

100755 3e84972fcf7f688f98999d1bd5c38eaf250efcc9 0       ks_centos7.cfg

sunilka@centos7 configs]$

Now, lest pust to Gitgub which is our remote repository. first check you have remote repository already existing there

sunilka@centos7 configs]$ git remote -v

sunilka@centos7 configs]$ 

add the remote repository, URL which you had while creating the repository.

sunilka@centos7 configs]$ git remote add origin https://github.com/sunilka/configs.git

sunilka@centos7 configs]$  git remote -v

origin  https://github.com/sunilka/configs.git (fetch)

origin  https://github.com/sunilka/configs.git (push)

sunilka@centos7 configs]$ 

where, 

      git remote add - add remote directory to Git

              origin - default name of the remote location

Push the file to GitHub using, use the same username and password which you use to create and access your GitHub account.

sunilka@centos7 configs]$ git push origin master

any changes made to the files, must be committed before Git push. 

sunilka@centos7 configs]$ git commit -m "CentOS 7 kickstart file" ks_centos7.cfg

[master 08632bb] CentOS 7 kickstart file

 1 file changed, 1 deletion(-)

sunilka@centos7 configs]$ git commit -m "CentOS 6 kickstart file" ks.cfg

[master 498a0ca] CentOS 6 kickstart file

 1 file changed, 2 deletions(-)

sunilka@centos7 configs]$ 

sunilka@centos7 configs]$ git push origin master

.

.

Counting objects: 9, done.

Compressing objects: 100% (6/6), done.

Writing objects: 100% (6/6), 591 bytes | 0 bytes/s, done.

Total 6 (delta 2), reused 0 (delta 0)

To https://github.com/sunilka/configs.git

   57a7eb3..498a0ca  master -> master

sunilka@centos7 configs]$ 

Take a look at your GitHub page, it should have been uploaded. 

you can make a localcopy from your GitHub account using the clone feature

sunilka@centos7 configs]$ mkdir gitclones

sunilka@centos7 configs]$ cd gitclones/

sunilka@centos7 gitclones]$ git clone https://github.com/sunilka/configs.git

Cloning into 'configs'...

remote: Counting objects: 10, done.

remote: Total 10 (delta 0), reused 0 (delta 0), pack-reused 10

Unpacking objects: 100% (10/10), done.

sunilka@centos7 gitclones]$ ls

configs

sunilka@centos7 gitclones]$ ls configs/

ks_centos7.cfg  ks.cfg

sunilka@centos7 gitclones]$

you have same files are in your GitHub repository.